MODULATORS OF INDOLEAMINE 2,3-DIOXYGENASE

Abstract

Provided are IDO inhibitor compounds of Formula I and pharmaceutically acceptable salts thereof, their pharmaceutical compositions, their methods of preparation, and methods for their use in the prevention and/or treatment of diseases.

##STR00001##

Claims

1. A compound of Formula I of Formula I ##STR00303## or a pharmaceutically acceptable salt thereof wherein: Q.sup.1 is C(O)O, C(O)CF.sub.2, C(O)NH, SO.sub.2, C(O), or a bond (i.e. is absent); Q.sup.2 is C.sub.1-4alkyl, C.sub.1-3alkyNHC.sub.1-3alkyl, or a bond (i.e. is absent); Q.sup.3 is C(O), C(O)NH, or a bond (i.e. is absent); R.sup.1 is C.sub.1-6alkyl, C.sub.2-4alkenyl, C.sub.3-7cycloalkyl, C.sub.5-9aryl, C.sub.5-9heteroaryl, 5 to 9 membered heterocycle; wherein R.sup.1 is optionally substituted with a substituent selected from C.sub.1-6alkyl, OC.sub.1-3alkyl, OC.sub.3-6cycloalkyl, oxo, and N(R.sup.2).sub.2 wherein each R.sup.2 is independently H, C.sub.1-6alkyl, C.sub.3-7cycloalkyl, C.sub.1-3alkylOC.sub.1-3alkyl, OC.sub.1-3alkylOC.sub.1-3alkyl C.sub.3-6cycloalkyl, CH.sub.2phenyl, or OCH.sub.2phenyl; R.sup.3 is C.sub.5-9aryl, C.sub.5-9heteroaryl, C.sub.1-6alkyl, C.sub.3-6cycloalkyl, C.sub.7-10bicycloalkyl, wherein R.sup.3 is optionally substituted with 1 or 2 substituents selected from halogen, C.sub.1-6alkyl, C.sub.1-3fluoroalkyl, C.sub.3-6cycloalkyl, OC.sub.1-3alkyl, SC.sub.1-3alkyl, C.sub.2-4alkenyl, C.sub.2-4alkynyl, OC.sub.2-4alkyny, phenyl, CN; R.sup.4 is C.sub.5-9aryl, C.sub.1-6alkyl, C.sub.1-3fluoroalkyl, C.sub.3-6cycloalkyl, C.sub.2-4alkenyl, C.sub.2-4alkynyl, or C.sub.3-6ether; and wherein each aryl and heteroaryl includes bicycles and wherein each heteroaryl, and heterocycle contains from 1 to 3 heteroatoms selected from O, N, and S.

2. A compound or salt according to claim 1 wherein Q.sup.1 is C(O)O, C(O)CF.sub.2, C(O)NH, SO.sub.2, or C(O).

3. A compound or salt according to claim 1 wherein Q.sup.2 is absent.

4. A compound or salt according to claim 1 wherein Q.sup.3 is C(O).

5. A compound or salt according to claim 1 wherein R.sup.1 is phenyl, a pyridine, an oxadiazole, oxo substituted oxadiazole, C.sub.1-6alkyl, C.sub.3-7cycloalkyl, C.sub.2-4alkenyl, a 5 or 6-membered heterocycle containing one or two heteroatoms selected from O and N, wherein R.sup.1 is optionally substituted with a substituent selected from C.sub.1-6alkyl, OC.sub.1-3alkyl, OC.sub.3-6cycloalkyl, and N(R.sup.2).sub.2 wherein each R.sup.2 is independently H, C.sub.1-6alkyl, C.sub.3-7cycloalkyl C.sub.1-3alkylOC.sub.1-3alkyl, OC.sub.1-3alkylOC.sub.1-3alkyl C.sub.3-6cycloalkyl, CH.sub.2phenyl, or OCH.sub.2phenyl.

6. A compound or salt according to claim 5 wherein R.sup.1 is phenyl, a pyridine, an oxadiazole, C.sub.1-6alkyl, C.sub.3-7cycloalkyl, or C.sub.2-4alkylenyl, wherein R.sup.1 is optionally substituted with a substituent selected from C.sub.1-6alkyl, OC.sub.1-3alkyl, and N(R.sup.2).sub.2 wherein each R.sup.2 is independently C.sub.1-6alkyl, or C.sub.3-6cycloalkyl.

7. A compound or salt according to claim 1 wherein R.sup.3 is thiophene, phenyl, pyridyl, benzoxazole, oxazole, C.sub.1-6alkyl, C.sub.3-6cycloalkyl, or C.sub.7-10bicycloalkyl, wherein R.sup.3 is optionally substituted with 1 or 2 substituents selected from halogen, C.sub.1-3alkyl, C.sub.1-3fluoroalkyl, OC.sub.1-3alkyl, SC.sub.1-3alkyl, C.sub.2-4alkenyl, C.sub.2-4alkynyl, and OC.sub.2-4alkynyl.

8. A compound or salt according to claim 7 wherein R.sup.3 is thiophene or phenyl optionally substituted with 1 or 2 substituents selected from halogen, C.sub.1-3alkyl, and C.sub.2-3alkynyl.

9. A compound or salt according to claim 1 wherein R.sup.4 is phenyl, C.sub.1-6alkyl, C.sub.1-3fluoroalkyl, C.sub.3-6cycloalkyl, C.sub.2-4alkynyl, or C.sub.3-6ether.

10. A compound or salt according to claim 9 wherein R.sup.4 is C.sub.1-6alkyl.

11. A compound or salt according to claim 1 wherein Q.sup.1 is C(O)O, C(O)CF.sub.2, C(O)NH, SO.sub.2, or C(O); Q.sup.2 is absent Q.sup.3 is C(O); R.sup.1 is phenyl, a pyridine, an oxadiazole, oxo substituted oxadiazole, C.sub.1-6alkyl, C.sub.3-7cycloalkyl, C.sub.2-4alkenyl, or a 5 or 6-membered heterocycle containing one or two heteroatoms selected from O and N, wherein R is optionally substituted with a substituent selected from C.sub.1-6alkyl, OC.sub.1-3alkyl, OC.sub.3-6cycloalkyl, and N(R.sup.2).sub.2 wherein each R.sup.2 is independently H, C.sub.1-6alkyl, C.sub.3-7cycloalkyl C.sub.1-3alkylOC.sub.1-3alkyl, OC.sub.1-3alkylOC.sub.1-3alkyl C.sub.3-6cycloalkyl, CH.sub.2phenyl, or OCH.sub.2phenyl; R.sup.3 is thiophene, phenyl, pyridyl, benzoxazole, oxazole, C.sub.1-6alkyl, C.sub.3-6cycloalkyl, or C.sub.7-10bicycloalkyl, wherein R.sup.3 is optionally substituted with 1 or 2 substituents selected from halogen, C.sub.1-3alkyl, C.sub.1-3fluoroalkyl, OC.sub.1-3alkyl, SC.sub.1-3alkyl, C.sub.2-4alkenyl, C.sub.2-4alkynyl, and OC.sub.2-4alkynyl; and R.sup.4 is phenyl, C.sub.1-6alkyl, C.sub.1-3fluoroalkyl, C.sub.3-6cycloalkyl, C.sub.2-4alkynyl, or C.sub.3-6ether.

12. A pharmaceutical composition comprising a compound or salt according to claim 1.

13. A method of treating a disease or condition that would benefit from inhibition of IDO1 comprising the step of administration of a composition according to claim 12.

14. The method of claim 13 wherein in said disease or condition, biomarkers of IDO activity are elevated.

15. The method of claim 13 wherein said biomarkers are plasma kynurenine or the plasma kynurenine/tryptophan ratio.

16. The method of claim 13 wherein said disease or condition is chronic viral infection; chronic bacterial infections; cancer; sepsis; or a neurological disorder.

17. The method of claim 13 wherein said chronic viral infections are those involving HIV, HBV, or HCV; said chronic bacterial infections are tuberculosis or prosthetic joint infection; and said neurological disorders are major depressive disorder, Huntington's disease, or Parkinson's disease.

18. The method of claim 17 wherein said disease or condition is inflammation associated with HIV infection; chronic viral infections involving hepatitis B virus or hepatitis C virus; cancer; or sepsis.

19-20. (canceled)

Description

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

[0072] Preferably Q.sup.1 is C(O)O, C(O)CF.sub.2, C(O)NH, SO.sub.2, or C(O).

[0073] Preferably Q.sup.2 is absent.

[0074] Preferably Q.sup.3 is C(O).

[0075] Preferably R.sup.1 is phenyl, a pyridine, an oxadiazole, oxo substituted oxadiazole, C.sub.1-6 alkyl, C.sub.3-7cycloalkyl, C.sub.2-4alkenyl, or a 5 or 6-membered heterocycle containing one or two heteroatoms selected from O and N, wherein R.sup.1 is optionally substituted with a substituent selected from C.sub.1-6alkyl, OC.sub.1-3alkyl, OC.sub.3-6cycloalkyl, and N(R.sup.2).sub.2 wherein each R.sup.2 is independently H, C.sub.1-6alkyl, C.sub.3-7cycloalkyl C.sub.1-3alkylOC.sub.1-3alkyl, OC.sub.1-3alkylOC.sub.1-3alkyl C.sub.3-6cycloalkyl, CH.sub.2phenyl, or OCH.sub.2phenyl. More preferably, R.sup.1 is phenyl, a pyridine, an oxadiazole, C.sub.1-6alkyl, C.sub.3-7cycloalkyl, or C.sub.2-4alkylenyl, wherein R.sup.1 is optionally substituted with a substituent selected from C.sub.1-6alkyl, OC.sub.1-3alkyl, and N(R.sup.2).sub.2 wherein each R.sup.2 is independently C.sub.1-6alkyl, or C.sub.3-6cycloalkyl.

[0076] Preferably R.sup.3 is thiophene, phenyl, pyridyl, benzoxazole, oxazole, C.sub.1-6alkyl, C.sub.3-6cycloalkyl, or C.sub.7-10bicycloalkyl, wherein R.sup.3 is optionally substituted with 1 or 2 substituents selected from halogen, C.sub.1-3alkyl, C.sub.1-3fluoroalkyl, OC.sub.1-3alkyl, SC.sub.1-3alkyl, C.sub.2-4alkenyl, C.sub.2-4alkynyl, and OC.sub.2-4alkynyl. More preferably R.sup.3 is thiophene or phenyl optionally substituted with 1 or 2 substituents selected from halogen, C.sub.1-3alkyl, and C.sub.2-3alkynyl.

[0077] Preferably R.sup.4 is phenyl, C.sub.1-6alkyl, C.sub.1-3fluoroalkyl, C.sub.3-6cycloalkyl, C.sub.2-4alkynyl, or C.sub.3-6ether. More preferably R.sup.4 is C.sub.1-6alkyl.

[0078] Preferably the stereochemistry of the depicted carbon to which R.sup.1-Q.sup.2 is bonded is as depicted below.

##STR00003##

[0079] Preferred pharmaceutical compositions include unit dosage forms. Preferred unit dosage forms include tablets.

[0080] In particular, it is expected that the compounds and composition of this invention will be useful for prevention and/or treatment of HIV; including the prevention of the progression of AIDS and general immunosuppression. It is expected that in many cases such prevention and/or treatment will involve treating with the compounds of this invention in combination with at least one other drug thought to be useful for such prevention and/or treatment. For example, the IDO inhibitors of this invention may be used in combination with other immune therapies such as immune checkpoints (PD1, CTLA4, ICOS, etc.) and possibly in combination with growth factors or cytokine therapies (IL21, IL-7, etc.).

[0081] In is common practice in treatment of HIV to employ more than one effective agent. Therefore, in accordance with another embodiment of the present invention, there is provided a method for preventing or treating a viral infection in a mammal mediated at least in part by a virus in the retrovirus family of viruses which method comprises administering to a mammal, that has been diagnosed with said viral infection or is at risk of developing said viral infection, a compound as defined in Formula I, wherein said virus is an HIV virus and further comprising administration of a therapeutically effective amount of one or more agents active against an HIV virus, wherein said agent active against the HIV virus is selected from the group consisting of Nucleotide reverse transcriptase inhibitors; Non-nucleotide reverse transcriptase inhibitors; Protease inhibitors; Entry, attachment and fusion inhibitors; Integrase inhibitors; Maturation inhibitors; CXCR4 inhibitors; and CCR5 inhibitors. Examples of such additional agents are Dolutegravir, Bictegravir, and Cabotegravir.

[0082] Pharmaceutically acceptable salt refers to pharmaceutically acceptable salts derived from a variety of organic and inorganic counter ions well known in the art and include, by way of example only, sodium, potassium, calcium, magnesium, ammonium, and tetraalkylammonium, and when the molecule contains a basic functionality, salts of organic or inorganic acids, such as hydrochloride, hydrobromide, tartrate, mesylate, acetate, maleate, and oxalate. Suitable salts include those described in P. Heinrich Stahl, Camille G. Wermuth (Eds.), Handbook of Pharmaceutical Salts Properties, Selection, and Use; 2002.

[0083] The present invention also includes pharmaceutically acceptable salts of the compounds described herein. As used herein, pharmaceutically acceptable salts refers to derivatives of the disclosed compounds wherein the parent compound is modified by converting an existing acid or base moiety to its salt form. Examples of pharmaceutically acceptable salts include, but are not limited to, mineral or organic acid salts of basic residues such as amines; alkali or organic salts of acidic residues such as carboxylic acids; and the like. The pharmaceutically acceptable salts of the present invention include the conventional non-toxic salts of the parent compound formed, for example, from non-toxic inorganic or organic acids. The pharmaceutically acceptable salts of the present invention can be synthesized from the parent compound which contains a basic or acidic moiety by conventional chemical methods. Generally, such salts can be prepared by reacting the free acid or base forms of these compounds with a stoichiometric amount of the appropriate base or acid in water or in an organic solvent, or in a mixture of the two; generally, nonaqueous media like ether, ethyl acetate, ethanol, isopropanol, or ACN are preferred.

[0084] The phrase pharmaceutically acceptable is employed herein to refer to those compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit/risk ratio.

[0085] In one embodiment, the pharmaceutical formulation containing a compound of Formula I or a salt thereof is a formulation adapted for oral or parenteral administration. In another embodiment, the formulation is a long-acting parenteral formulation. In a further embodiment, the formulation is a nano-particle formulation.

[0086] The present invention is directed to compounds, compositions and pharmaceutical compositions that have utility as novel treatments for immunosuppresion. While not wanting to be bound by any particular theory, it is thought that the present compounds are able to inhibit the enzyme that catalyzes the oxidative pyrrole ring cleavage reaction of I-Trp to N-formylkynurenine utilizing molecular oxygen or reactive oxygen species.

[0087] Therefore, in another embodiment of the present invention, there is provided a method for the prevention and/or treatment of HIV; including the prevention of the progression of AIDS and general immunosuppression.

EXAMPLES

[0088] Compounds of the invention can be prepared by one skilled in the art according to the following general synthetic scheme.

##STR00004## ##STR00005##

[0089] The following examples serve to more fully describe the manner of making and using the above-described invention. It is understood that these examples in no way serve to limit the true scope of the invention, but rather are presented for illustrative purposes. In the examples and the synthetic schemes below, the following abbreviations have the following meanings. If an abbreviation is not defined, it has its generally accepted meaning.

TABLE-US-00001 abbreviation meaning Boc tert-butoxycarbonyl BOP benzotriazole-1-yl-oxy-tris-(dimethylamino)-phosphonium hexafluorophosphate C. degrees Celsius COMU (1-cyano-2-ethoxy-2-oxoethylidenaminooxy)dimethyl- amino-morpholino-carbenium hexafluorophosphate DBU 1,8-diazabicyclo[5.4.0]undec-7-ene DCM dichloromethane DEA diethylamine DIEA N,N-diisopropylethylamine DMAP 4-(dimethylamino)pyridine DMF N,N-dimethylformamide DMSO dimethylsulfoxide ESI electrospray ionization h or hr hours HATU (1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5- b]pyridinium 3-oxid hexafluorophosphate) HPLC high performance liquid chromatography J coupling constant in Hz LCMS liquid chromatography - mass spectrometry M molar mg milligram min minute mL milliliters mM millimolar mmol millimole L or uL microliters M or uM micromolar MS mass spectrum N normal NMR nuclear magnetic resonance PE petroleum ether ppm parts per million PPTS pyridinium p-toluenesulfonate RT room temperature Rf retention factor T3P propanephosphonic acid anhydride TEA triethylamine TFA trifluoroacetic acid TFAA trifluoroacetic anhydride THF tetrahydrofuran TLC thin layer chromatography

Equipment Description

[0090] .sup.1H NMR spectra were recorded on a Varian 400 spectrometer. Chemical shifts are expressed in parts per million (ppm, units). Coupling constants are in units of hertz (Hz). Splitting patterns describe apparent multiplicities and are designated as s (singlet), d (doublet), t (triplet), q (quartet), quint (quintet), m (multiplet), br (broad).

[0091] The analytical low-resolution mass spectra (MS) were recorded on Waters ACQUITY UPLC with SQ Detectors using a Waters BEH C18, 2.150 mm, 1.7 m using a gradient elution method. Solvent A: 0.1% formic acid (FA) in water. Solvent B: 0.1% FA in acetonitrile; 30% B for 0.5 min followed by 30-100% B over 2.5 min.

Synthesis of Amine Intermediate tert-butyl 4-(2-amino-2-phenylethyl)piperidine-1-carboxylate

[0092] ##STR00006##

Step 1: Preparation of tert-butyl 4-(2-(methoxy(methyl)amino)-2-oxoethyl)piperidine-1-carboxylate

[0093] ##STR00007##

[0094] To a stirred solution of 2-(1-(tert-butoxycarbonyl)piperidin-4-yl)acetic acid (10.0 g, 41.1 mmol), N,O-dimethylhydroxylamine hydrochloride (4.21 g, 43.2 mmol), and DIEA (21.5 mL, 123 mmol) in DMF (75 mL) at 0 C. was added 50% T3P/EtOAc (34.0 g, 53.4 mmol) by slow addition over 3 minutes. The resulting solution was stirred at 0 C. After 2.5 hours the solution was partitioned between EtOAc and water and the phases separated. The aqueous phase was extracted with one additional portion of EtOAc. The combined EtOAc solutions were washed with 10% aqueous citric acid (2), saturated aqueous NaHCO.sub.3 (2), dried over Na.sub.2SO.sub.4, and concentrated to dryness at reduced pressure to give the title compound as a colorless oil (9.16 g, 78% yield). LCMS (ESI) m/z calcd for C.sub.14H.sub.26N.sub.2O.sub.4: 286.2. Found: 287.4 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 4.07 (d, J=13.2 Hz, 2H), 3.67 (s, 3H), 3.18 (s, 3H), 2.73 (t, J=12.9 Hz, 2H), 2.35 (d, J=6.4 Hz, 2H), 1.93-2.10 (m, 1H), 1.71 (d, J=12.8 Hz, 2H), 1.45 (s, 9H), 1.08-1.21 (m, 2H).

Step 2: Preparation of tert-butyl 4-(2-oxo-2-phenylethyl)piperidine-1-carboxylate

[0095] ##STR00008##

[0096] To a stirred solution of tert-butyl 4-(2-(methoxy(methyl)amino)-2-oxoethyl)piperidine-1-carboxylate (9.13 g, 31.9 mmol) in anhydrous THE (106 mL) at 0 C. was added 1M PhMgBr (38.3 mL, 38.3 mmol) by dropwise addition. After 10 minutes the solution was allowed to warm to RT. After 2 hours the solution was quenched by addition of saturated NH.sub.4Cl. The resulting mixture was partitioned between water and EtOAc and the phases separated. The aqueous phase was extracted with EtOAc (2). The combined EtOAc solutions were washed with water (1), saturated brine (1), dried over Na.sub.2SO.sub.4 and concentrated at reduced. The residue was subjected to flash chromatography (silica gel, 0-50% EtOAc/hexanes, gradient elution) to afford the title compound as a white crystalline solid (9.04 g, 93% yield). LCMS (ESI) m/z calcd for C.sub.18H.sub.25NO.sub.3: 303.2. Found: 204.2 (M+1-Boc).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.95 (d, J=7.3 Hz, 2H), 7.53-7.61 (m, 1H), 7.41-7.52 (m, 2H), 4.09 (d, J=13.2 Hz, 2H), 2.90 (d, J=6.6 Hz, 2H), 2.70-2.81 (m, 2H), 2.06-2.25 (m, 1H), 1.75 (d, J=12.6 Hz, 2H), 1.46 (s, 9H), 1.13-1.27 (m, 2H).

Step 3: Preparation of tert-butyl 4-(2-(hydroxyimino)-2-phenylethyl)piperidine-1-carboxylate

[0097] ##STR00009##

[0098] A solution of tert-butyl 4-(2-oxo-2-phenylethyl)piperidine-1-carboxylate (3.40 g, 11.2 mmol), NaOAc (4.60 g, 56.0 mmol), and hydroxylamine hydrochloride (1.56 g, 22.4 mmol) in 2:1 EtOH/H.sub.2O (80 mL) was stirred at 90 C. for 3 hours and then cooled to RT. The solution was partitioned between EtOAc and water and the phases separated. The aqueous phase was extracted with two additional portions of EtOAc. The combined EtOAc solutions were washed with brine (1), dried over Na.sub.2SO.sub.4 and concentrated at reduced pressure to give the title compound as a white crystalline solid (3.52 g, 99% yield). LCMS (ESI) m/z calcd for C.sub.18H.sub.26N.sub.2O.sub.3: 318.2. Found: 319.4 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.56-7.65 (m, 2H), 7.33-7.46 (m, 3H), 4.04 (br s, 2H), 2.81 (d, J=7.3 Hz, 2H), 2.63 (t, J=12.1 Hz, 2H), 1.75-1.87 (m, 1H), 1.64 (d, J=13.0 Hz, 2H), 1.45 (s, 9H), 1.14-1.33 (m, 2H).

Step 4: Preparation of tert-butyl 4-(2-amino-2-phenylethyl)piperidine-1-carboxylate

[0099] ##STR00010##

[0100] A solution of tert-butyl 4-(2-(hydroxyimino)-2-phenylethyl)piperidine-1-carboxylate (3.52 g, 11.1 mmol) in MeOH (75 mL) was subjected to hydrogenation at 60 psi in the presence of 10% Pd/C (0.25 g). After 18 hours the reaction vessel was purged with nitrogen, catalyst removed by filtration, and the filtrate concentrated at reduced pressure to give the title compound as a colorless oil (3.35 g, 100%). LCMS (ESI) m/z calcd for C.sub.18H.sub.28N.sub.2O.sub.2: 304.2. Found: 305.4 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.20-7.38 (m, 5H), 3.87-4.18 (m, 3H), 2.55-2.70 (m, 2H), 1.51-1.88 (m, 6H), 1.34-1.49 (m, 10H), 0.99-1.21 (m, 2H).

Example 1: tert-butyl 4-(2-(5-ethylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0101] ##STR00011##

[0102] To a stirred solution of tert-butyl 4-(2-amino-2-phenylethyl)piperidine-1-carboxylate (50.0 mg, 0.164 mmol), 5-ethylthiophene-2-carboxylic acid (28.2 mg, 0.181 mmol), and DIEA (86 uL mL, 0.49 mmol) in DMF (2 mL) was added HATU (94 mg, 0.25 mmol). The resulting solution was stirred at RT. After 18 hours the solution was treated with 2M ammonia/MeOH (3 mL). After stirring at RT for an additional 1 hour, the solution was partitioned between EtOAc and brine and the phases separated. The EtOAc solution was washed with 10% aqueous citric acid (2), saturated aqueous NaHCO.sub.3 (2), dried over Na.sub.2SO.sub.4, and concentrated to dryness at reduced pressure. The residue was subjected to flash chromatography (silica gel, 0-100% EtOAc/hexanes, gradient elution) to afford the title compound as a white solid (54 mg, 74% yield). LCMS (ESI) m/z calcd for C.sub.25H.sub.34N.sub.2O.sub.3S: 442.2. Found: 465.3 (M+Na).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.28-7.45 (m, 6H), 6.80 (d, J=3.5 Hz, 1H), 6.03 (d, J=8.3 Hz, 1H), 5.22-5.37 (m, 1H), 4.09 (br s, 2H), 2.89 (q, J=7.4 Hz, 2H), 2.67 (t, J=12.5 Hz, 2H), 1.69-1.98 (m, 4H), 1.42-1.55 (m, 10H), 1.35 (t, J=7.6 Hz, 3H), 1.10-1.30 (m, 2H).

Example 2: tert-butyl 4-(2-(5-bromothiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0103] ##STR00012##

[0104] The title compound was prepared in 77% yield from tert-butyl 4-(2-amino-2-phenylethyl)piperidine-1-carboxylate and 5-bromothiophene-2-carboxylic acid as described herein for the preparation of tert-butyl 4-(2-(5-ethylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.23H.sub.29BrN.sub.2O.sub.3S: 492.1. Found: 493.2 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.27-7.40 (m, 5H), 7.20 (d, J=3.9 Hz, 1H), 7.01 (d, J=3.9 Hz, 1H), 6.01 (d, J=8.2 Hz, 1H), 5.22 (q, J=8.2 Hz, 1H), 3.95-4.10 (m, 2H), 2.61 (t, J=12.3 Hz, 2H), 1.65-1.94 (m, 4H), 1.35-1.50 (m, 10H), 1.01-1.30 (m, 2H).

Example 3: tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0105] ##STR00013##

[0106] To a stirred solution of tert-butyl 4-(2-amino-2-phenylethyl)piperidine-1-carboxylate (0.785 g, 2.58 mmol) in DMF (30 mL) was added COMU (1.63 g, 3.81 mmol) followed by DIEA (1.36 mL, 7.79 mmol) and then 5-chlorothiophene-2-carboxylic acid (0.544 g, 3.35 mmol). After stirring at RT for 2 hours, the solution was quenched with water and partitioned between DCM and saturated aqueous Na.sub.2CO.sub.3. The phases were separated and the aqueous phase extracted with DCM (2). The combined DCM solutions were concentrated to dryness at reduced pressure and the residue purified by reverse phase HPLC (C18, MeCN/water with ammonium carbonate modifier) to afford the title compound. LCMS (ESI) m/z calcd for C.sub.23H.sub.29ClN.sub.2O.sub.3S: 448.1. Found: 449.1 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.22-7.44 (m, 6H), 6.90 (d, J=4.0 Hz, 1H), 6.00 (d, J=8.1 Hz, 1H), 5.25 (q, J=8.1 Hz, 1H), 4.07 (br s, 2H), 2.58-2.71 (m, 2H), 1.69-1.96 (m, 4H), 1.38-1.53 (m, 10H), 1.07-1.34 (m, 2H).

Example 4: tert-butyl 4-(2-(5-ethynylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0107] ##STR00014##

Step 1: Preparation of tert-butyl 4-(2-phenyl-2-(5-((trimethylsilyl)ethynyl)thiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0108] ##STR00015##

[0109] A stirred solution of tert-butyl 4-(2-(5-bromothiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate (76 mg, 0.15 mmol), tetrakis(triphenylphosphine)palladium(0) (18 mg, 0.015 mmol), and copper(I) iodide (2.9 mg, 0.015 mmol) in THE (3 mL) was sparged with nitrogen for 5 minutes, and then treated with TEA (0.107 mL, 0.770 mmol) followed by TMS-acetylene (0.107 mL, 0.770 mmol). The resulting solution was heated to 85 C. in a sealed vessel. After 30 minutes LCMS indicated complete reaction. The mixture was cooled to RT, filtered to removed solids, and the filtrate concentrated to dryness at reduced pressure. The residue was subjected to flash chromatography (silica gel, 0-100% EtOAc/hexanes, gradient elution) to afford the title compound as a light yellow foam (68 mg, 86%). LCMS (ESI) m/z calcd for C.sub.28H.sub.38N.sub.2O.sub.3SSi: 510.2. Found: 511.4 (M+1).sup.+.

Step 2: Preparation of tert-butyl 4-(2-(5-ethynylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0110] ##STR00016##

[0111] To a stirred solution of tert-butyl 4-(2-phenyl-2-(5-((trimethylsilyl)ethynyl)thiophene-2-carboxamido)ethyl)piperidine-1-carboxylate (68 mg, 0.13 mmol) in MeOH (3 mL) was added K.sub.2CO.sub.3 (92 mg, 0.67 mmol). The resulting mixture was stirred at RT. After 1 hour the mixture was partitioned between EtOAc and 10% aqueous citric acid and the phases separated. The EtOAc solution was washed with saturated aqueous NaHCO.sub.3 (2), dried over Na.sub.2SO.sub.4 and concentrated at reduced pressure. The residue was subjected to flash chromatography (silica gel, 0-100% EtOAc/hexanes, gradient elution) to afford the title compound as a white solid (42 mg, 72% yield). LCMS (ESI) m/z calcd for C.sub.25H.sub.30N.sub.2O.sub.3S: 438.2. Found: 439.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.26-7.40 (m, 6H), 7.18 (d, J=3.9 Hz, 1H), 6.09 (d, J=8.2 Hz, 1H), 5.24 (q, J=7.8 Hz, 1H), 4.04 (br s, 2H), 3.42 (s, 1H), 2.54-2.68 (m, 2H), 1.66-1.95 (m, 4H), 1.37-1.50 (m, 10H), 1.02-1.30 (m, 2H).

Example 5: tert-butyl 4-(2-(4-ethynylbenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0112] ##STR00017##

Step 1: Preparation of tert-butyl 4-(2-(4-bromobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0113] ##STR00018##

[0114] The title compound was prepared in 85% yield from tert-butyl 4-(2-amino-2-phenylethyl)piperidine-1-carboxylate and 4-bromobenzoic acid as described herein for the preparation of tert-butyl 4-(2-(5-ethylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.25H.sub.31BrN.sub.2O.sub.3: 486.2. Found: 487.2 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.52-7.65 (m, 4H), 7.23-7.40 (m, 5H), 6.21 (d, J=8.2 Hz, 1H), 5.23-5.33 (m, 1H), 3.97-4.10 (m, 2H), 2.53-2.67 (m, 2H), 1.66-1.95 (m, 4H), 1.36-1.48 (m, 10H), 1.07-1.29 (m, 2H).

Steps 2 and 3: Preparation of tert-butyl 4-(2-(4-ethynylbenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0115] ##STR00019##

[0116] The title compound was prepared in two steps in 31% overall yield from tert-butyl 4-(2-(4-bromobenzamido)-2-phenylethyl)piperidine-1-carboxylate as described herein for the preparation of tert-butyl 4-(2-(5-ethynylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.27H.sub.32N.sub.2O.sub.3: 432.2. Found: 433.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.68 (d, J=8.2 Hz, 2H), 7.51 (d, J=8.2 Hz, 2H), 7.25-7.38 (m, 5H), 6.21 (d, J=7.8 Hz, 1H), 5.28 (q, J=7.8 Hz, 1H), 4.03 (br s, 2H), 3.17 (s, 1H), 2.53-2.66 (m, 2H), 1.63-1.95 (m, 4H), 1.35-1.46 (m, 10H), 0.98-1.27 (m, 2H).

Example 6: tert-butyl 4-(2-(4-ethynyl-3-fluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0117] ##STR00020##

Step 1: Preparation of tert-butyl 4-(2-(4-bromo-3-fluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0118] ##STR00021##

[0119] The title compound was prepared in 82% yield from tert-butyl 4-(2-amino-2-phenylethyl)piperidine-1-carboxylate and 4-bromo-3-fluorobenzoic acid as described herein for the preparation of tert-butyl 4-(2-(5-ethylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.25H.sub.30BrFN.sub.2O.sub.3: 504.1. Found: 505.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.60 (dd, J=8.2, 6.6 Hz, 1H), 7.52 (dd, J=9.0, 2.0 Hz, 1H), 7.27-7.41 (m, 6H), 6.24 (d, J=8.2 Hz, 1H), 5.21-5.31 (m, 1H), 3.99-4.09 (m, 2H), 2.54-2.66 (m, 2H), 1.66-1.93 (m, 4H), 1.34-1.47 (m, 10H), 1.06-1.29 (m, 2H).

Steps 2 and 3: Preparation of tert-butyl 4-(2-(4-ethynyl-3-fluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0120] ##STR00022##

[0121] The title compound was prepared in two steps in 57% overall yield from tert-butyl 4-(2-(4-bromo-3-fluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate as described herein for the preparation of tert-butyl 4-(2-(5-ethynylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.27H.sub.31FN.sub.2O.sub.3: 450.2. Found: 451.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.43-7.57 (m, 3H), 7.27-7.42 (m, 5H), 6.25 (d, J=8.2 Hz, 1H), 5.27 (q, J=7.8 Hz, 1H), 4.05 (br s, 2H), 3.41 (s, 1H), 2.53-2.67 (m, 2H), 1.65-1.96 (m, 4H), 1.34-1.52 (m, 10H), 1.03-1.31 (m, 2H).

Example 7: ethyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropylethyl)piperidine-1-carboxylate

[0122] ##STR00023##

Step 1: Preparation of tert-butyl 4-(2-cyclopropyl-2-oxoethyl)piperidine-1-carboxylate

[0123] ##STR00024##

[0124] To a solution of tert-butyl 4-(2-(methoxy(methyl)amino)-2-oxoethyl)piperidine-1-carboxylate (13.4 g, 46.9 mmol) in THE (200 mL) 78 C., was slowly added a solution of 1M cyclopropylmagnesium bromide in THE (141 mL, 141 mmol). After stirring at RT overnight, the reaction was quenched with saturated aqueous NH.sub.4Cl and extracted with EtOAc. The organic layer was washed with brine, dried over Na.sub.2SO.sub.4, filtered and concentrated to give the crude product which was purified by flash chromatography (silica gel, 0-15% EtOAc in PE, gradient elution) to afford the title compound (9.0 g, 72% yield). LCMS (ESI) m/z calcd for C.sub.15H.sub.25NO.sub.3: 267.2. Found: 268.3 (M+1).sup.+.

Step 2: Preparation of tert-butyl 4-(2-amino-2-cyclopropylethyl)piperidine-1-carboxylate

[0125] ##STR00025##

[0126] To a solution of tert-butyl 4-(2-cyclopropyl-2-oxoethyl)piperidine-1-carboxylate (500 mg, 1.87 mmol) in MeOH (8 mL), was added NH.sub.4OAc (2.88 g, 37.3 mmol) and NaBH.sub.3CN (1.18 mg, 18.7 mmol) successively. After stirring at RT overnight, the reaction was quenched with saturated aqueous NH.sub.4Cl and extracted with EtOAc. The organic layer was washed with brine, dried over Na.sub.2SO.sub.4, filtered and concentrated to give the title compound (510 mg, quantitative yield), which was used in the following step without purification. LCMS (ESI) m/z calcd for C.sub.15H.sub.28N.sub.2O.sub.2: 268.2. Found: 269.4 (M+1).sup.+.

Step 3: Preparation of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropyl ethyl)piperidine-1-carboxylate

[0127] ##STR00026##

[0128] To a solution of tert-butyl 4-(2-amino-2-cyclopropylethyl)piperidine-1-carboxylate (502 mg, 1.87 mmol) in DMF (8 mL), was added 5-chlorothiophene-2-carboxylic acid (365 mg, 2.24 mmol), DIEA (1.13 mL, 6.48 mmol) and HATU (853 mg, 2.24 mmol) successively. After stirring at RT for 3 hours, the reaction was diluted with water and extracted with EtOAc. The organic layer was washed with brine, dried over Na.sub.2SO.sub.4, filtered and concentrated to give the crude product which was purified by flash chromatography (silica gel, 0-20% EtOAc in PE, gradient elution) to afford the title compound (650 mg, 84% yield). LCMS (ESI) m/z calcd for C.sub.2H.sub.29ClN.sub.2O.sub.3S: 412.2. Found: 413.7 (M+1).sup.+.

Step 4: Preparation of 5-chloro-N-(1-cyclopropyl-2-(piperidin-4-yl)ethyl)thiophene-2-carboxamide hydrochloride

[0129] ##STR00027##

[0130] To a solution of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropyl ethyl)piperidine-1-carboxylate (200 mg, 0.35 mmol) in DCM (2 mL), was added 4 M HCl in dioxane (3 mL) dropwise. After stirring at RT for 2 hours, the reaction mixture was concentrated to afford the title compound (220 mg, 100% yield), which was used in the following step without purification. LCMS (ESI) m/z calcd for C.sub.15H.sub.21ClN.sub.2OS: 312.1. Found: 313.7 (M+1).sup.+

Step 5: Preparation of ethyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropylethyl) piperidine-1-carboxylate

[0131] ##STR00028##

[0132] To a solution of 5-chloro-N-(1-cyclopropyl-2-(piperidin-4-yl)ethyl)thiophene-2-carboxamide (140 mg, 0.448 mmol), DIEA (0.37 mL, 2.24 mmol) in DCM (2 mL) at 0 C., was added ethyl chloroformate (0.13 mL, 1.34 mmol) dropwise. After stirring at RT for 2 hours, the reaction was quenched with saturated aqueous NaHCO.sub.3 solution and extracted with EtOAc. The organic layer was washed with brine, dried over Na.sub.2SO.sub.4, filtered and concentrated to give the crude product which was purified by flash chromatography (silica gel, 0-20% EtOAc in PE, gradient elution) to afford the title compound (93 mg, 54% yield). LCMS (ESI) m/z calcd for C.sub.18H.sub.25ClN.sub.2O.sub.3S: 384.1. Found: 385.3 (M+1).sup.+. .sup.1H NMR (400 MHz, DMSO-d.sub.6) 8.34 (d, J=8.8 Hz, 1H), 7.68 (d, J=4.1 Hz, 1H), 7.17 (d, J=4.0 Hz, 1H), 4.00 (q, J=7.1 Hz, 2H), 3.95-3.81 (m, 2H), 3.47-3.38 (m, 1H), 2.79-2.58 (m, 2H), 1.72-1.54 (m, 3H), 1.52-1.42 (m, 2H), 1.15 (t, J=7.1 Hz, 3H), 1.10-0.99 (m, 1H), 0.98-0.86 (m, 2H), 0.50-0.42 (m, 1H), 0.39-0.32 (m, 1H), 0.31-0.23 (m, 1H), 0.21-0.13 (m, 1H).

Synthesis of Intermediate (S)-tert-butyl 4-(2-amino-2-cyclopropylethyl)piperidine-1-carboxylatehydrochloride

[0133] ##STR00029##

Step 1: Preparation of (S,E)-tert-butyl 4-(2-((tert-butylsulfinyl)imino)ethyl)piperidine-1-carboxylate

[0134] ##STR00030##

[0135] To a solution of (S)-2-methylpropane-2-sulfinamide (1.76 g, 14.5 mmol) in DCM (36 mL) was added PPTS (0.166 g, 0.660 mmol) and magnesium sulfate (3.97 g, 33.0 mmol) followed by N-Boc-piperidineacetaldehyde (3.00 g, 13.2 mmol) and the mixture was stirred at ambient temperature for 18 hours. The mixture was filtered and the filtrate concentrated. The material was subjected to flash chromatography (silica gel, dry loading, 0-40% EtOAc/hexanes, gradient elution) to provide the title compound (4.04 g, 93% yield) as an off-white solid. LCMS (ESI) m/z calcd for C.sub.16H.sub.30N.sub.2S: 330.2. Found: 331.4 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 8.05 (t, J=4.9 Hz, 1H), 4.07 (br s, 2H), 2.70 (t, J=12.1 Hz, 2H), 2.41-2.53 (m, 2H), 1.91 (ddd, J=11.0, 7.3, 3.9 Hz, 1H), 1.64-1.77 (m, 3H), 1.44 (s, 9H), 1.11-1.27 (m, 10H).

Step 2: Preparation of tert-butyl 4-((S)-2-cyclopropyl-2-((S)-1,1-dimethylethylsulfinamido) ethyl)piperidine-1-carboxylate

[0136] ##STR00031##

[0137] To a solution of tert-butyl (S,E)-4-(2-((tert-butylsulfinyl)imino)ethyl)piperidine-1-carboxylate (1.60 g, 4.84 mmol) in DCM (120 mL) at ambient temperature under a nitrogen atmosphere was added dropwise in 10 minutes 0.5M cyclopropylmagnesium bromide/THF (10.7 mL, 5.33 mmol). After stirring for 1 hour, saturated NH.sub.4C/water was added and the mixture was extracted with DCM. The organic phase was washed with water, brine, dried (Na.sub.2SO.sub.4), concentrated and dried in vacuo to provide a thick oil. The material was subjected to flash chromatography (silica gel, dry loading, 0-20% acetone/hexanes, gradient elution) to provide the title compound (0.88 g, 49% yield). LCMS (ESI) m/z calcd for C.sub.19H.sub.36N.sub.2O.sub.3S: 372.2. Found: 373.4 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 4.07 (br s, 2H), 3.12 (br s, 1H), 2.57-2.78 (m, 2H), 2.50 (d, J=6.3 Hz, 1H), 1.52-1.76 (m, 6H), 1.44 (s, 9H), 1.21 (s, 9H), 1.02-1.15 (m, 1H), 0.77-0.93 (m, 1H), 0.54-0.67 (m, 2H), 0.42 (dd, J=9.0, 4.7 Hz, 1H), 0.19-0.31 (m, 1H).

Step 3: Preparation of (S)-tert-butyl 4-(2-amino-2-cyclopropylethyl)piperidine-1-carboxylatehydrochloride

[0138] ##STR00032##

[0139] To a solution of 4-((S)-2-cyclopropyl-2-((S)-1,1-dimethylethylsulfinamido) ethyl)piperidine-1-carboxylate (550 mg, 1.48 mmol) in MeOH (8.5 mL) was added 4M HCl/dioxane (0.369 mL, 1.48 mmol) and the mixture was stirred at ambient temperature for 30 minutes. The mixture was concentrated and the resulting pale yellow solid was dried in vacuo to provide the title compound (450 mg, 95% yield) as on off-white solid. LCMS (ESI) m/z calcd for C.sub.15H.sub.28N.sub.2O.sub.2: 268.2. Found: 269.4 (M+1).sup.+. .sup.1H NMR (400 MHz, DMSO-d.sub.6) 7.90 (br s, 3H), 3.89 (d, J=10.5 Hz, 2H), 2.65 (br s, 2H), 1.44-1.74 (m, 5H), 1.36 (s, 9H), 0.75-1.00 (m, 3H), 0.53-0.62 (m, 1H), 0.46-0.52 (m, 1H), 0.42 (dd, J=9.4, 4.7 Hz, 1H), 0.23-0.34 (m, 1H).

Example 8: (S)-tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropylethyl)piperidine-1-carboxylate

[0140] ##STR00033##

[0141] To a suspension of tert-butyl (S)-4-(2-amino-2-cyclopropylethyl)piperidine-1-carboxylate hydrochloride (30 mg, 0.112 mmol) in EtOAc (1.5 mL) was added 5-chlorothiophene-2-carboxylic acid (20.0 mg, 0.123 mmol), DIEA (0.078 mL, 0.45 mmol) and 50% T3P/EtOAc (78 mg, 0.123 mmol). The mixture was stirred at ambient temperature for 18 hours then diluted with EtOAc and the solution washed with water. The organic phase was dried (Na.sub.2SO.sub.4), concentrated and the residue subjected to flash chromatography (silica gel, dry loading, 0-30% EtOAc/hexanes, gradient elution) to provide the title compound (12 mg, 26%) as a solid foam. LCMS (ESI) m/z calcd for C.sub.20H.sub.29ClN.sub.2O.sub.3S: 412.2. Found: 413.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.22 (d, J=3.9 Hz, 1H), 6.88 (d, J=3.9 Hz, 1H), 5.64 (d, J=8.9 Hz, 1H), 4.03 (d, J=12.1 Hz, 2H), 3.42-3.65 (m, 1H), 2.54-2.73 (m, 2H), 1.78 (d, J=13.3 Hz, 1H), 1.47-1.65 (m, 4H), 1.42 (s, 9H), 0.98-1.33 (m, 1H), 0.75-0.92 (m, 2H), 0.51-0.64 (m, 1H), 0.35-0.50 (m, 2H), 0.27 (dt, J=9.5, 4.8 Hz, 1H).

Example 9: (S)-tert-butyl 4-(2-cyclopropyl-2-(5-methylthiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0142] ##STR00034##

[0143] The title compound was prepared from tert-butyl (S)-4-(2-amino-2-cyclopropylethyl)piperidine-1-carboxylate hydrochloride and 5-methylthiophene-2-carboxylic acid as described herein for the synthesis of (S)-tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropylethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.21H.sub.32N.sub.2O.sub.3S: 392.2. Found: 393.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.30 (d, J=3.5 Hz, 1H), 6.74 (d, J=3.5 Hz, 1H), 5.67 (d, J=9.0 Hz, 1H), 4.04 (d, J=12.9 Hz, 2H), 3.59 (t, J=7.2 Hz, 1H), 2.64 (t, J=12.9 Hz, 2H), 2.51 (s, 3H), 1.81 (d, J=13.3 Hz, 1H), 1.50-1.66 (m, 6H), 1.44 (s, 9H), 0.77-0.91 (m, 1H), 0.50-0.61 (m, 1H), 0.37-0.50 (m, 2H), 0.28 (dt, J=9.1, 4.6 Hz, 1H).

Example 10: (S)-tert-butyl 4-(2-cyclopropyl-2-(5-ethylthiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0144] ##STR00035##

[0145] The title compound was prepared from tert-butyl (S)-4-(2-amino-2-cyclopropylethyl)piperidine-1-carboxylate hydrochloride and 5-ethylthiophene-2-carboxylic acid as described herein for the synthesis of (S)-tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropylethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.22H.sub.34N.sub.2O.sub.3S: 406.2. Found: 407.4 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.33 (d, J=3.5 Hz, 1H), 6.77 (d, J=3.1 Hz, 1H), 5.67 (d, J=9.0 Hz, 1H), 4.04 (d, J=12.9 Hz, 2H), 3.60 (t, J=7.2 Hz, 1H), 2.86 (q, J=7.7 Hz, 2H), 2.65 (t, J=12.9 Hz, 2H), 1.82 (d, J=12.9 Hz, 1H), 1.51-1.66 (m, 6H), 1.44 (s, 9H), 1.32 (t, J=7.6 Hz, 3H), 0.77-0.91 (m, 1H), 0.50-0.61 (m, 1H), 0.37-0.49 (m, 2H), 0.28 (dt, J=9.2, 4.8 Hz, 1H).

Example 11: (S)-ethyl 4-(2-cyclopropyl-2-(5-methylthiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0146] ##STR00036##

[0147] The title compound was prepared in two steps from (S)-tert-butyl 4-(2-cyclopropyl-2-(5-methylthiophene-2-carboxamido)ethyl)piperidine-1-carboxylate as described herein for the preparation of ethyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropylethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.19H.sub.28N.sub.2O.sub.3S: 364.2. Found: 365.3 (M+1). .sup.1H NMR (400 MHz, CDCl.sub.3) 7.30 (d, J=3.1 Hz, 1H), 6.74 (d, J=3.1 Hz, 1H), 5.66 (d, J=8.9 Hz, 1H), 4.10 (q, J=7.0 Hz, 4H), 3.50-3.67 (m, 1H), 2.70 (t, J=12.7 Hz, 2H), 2.51 (s, 3H), 1.84 (d, J=12.9 Hz, 1H), 1.51-1.67 (m, 5H), 1.24 (t, J=6.8 Hz, 3H), 0.99-1.20 (m, 1H), 0.75-0.93 (m, 1H), 0.51-0.62 (m, 1H), 0.36-0.49 (m, 2H), 0.28 (dt, J=9.1, 4.6 Hz, 1H).

Example 12: ethyl (S)-4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropyl ethyl)piperidine-1-carboxylate

[0148] ##STR00037##

Step 1: Preparation of (S)-5-chloro-N-(1-cyclopropyl-2-(piperidin-4-yl)ethyl)thiophene-2-carboxamide hydrochloride

[0149] ##STR00038##

[0150] To a solution of tert-butyl (S)-4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropyl ethyl)piperidine-1-carboxylate (40 mg, 0.097 mmol) in DCM (0.5 mL) was added 4 M HCl in dioxane (1.0 mL). After stirred at RT for 1 hour, the reaction mixture was concentrated under vacuum to afford the title compound (35 mg, 100% yield) as an HCl salt, which was used in the following step directly. LCMS (ESI) m/z calcd for C.sub.15H.sub.21ClN.sub.2OS: 312.1. Found: 313.2 (M+1).sup.+.

Step 2: Preparation of ethyl (S)-4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropyl ethyl)piperidine-1-carboxylate

[0151] ##STR00039##

[0152] To a stirred solution of (S)-5-chloro-N-(1-cyclopropyl-2-(piperidin-4-yl)ethyl)thiophene-2-carboxamide hydrochloride (35 mg, 0.097 mmol) in DCM (1 mL) at 0 C. was added DIEA (50 mg, 0.38 mmol) followed by ethyl chloroformate (31 mg, 0.29 mmol). After stirring at RT for 2 hours, the reaction mixture was partitioned between DCM and water, and the layers were separated. The organic layer was washed with aqueous NaHCO.sub.3, brine, and dried over Na.sub.2SO.sub.4. Solvent was removed under vacuum and the residue was purified by reverse phase HPLC (C18, 10-50% MeCN in water with 0.1% formic acid) to afford the title compound (16 mg, 43% yield) as a white solid. LCMS (ESI) m/z calcd for C.sub.18H.sub.25ClN.sub.2O.sub.3S: 384.1. Found: 385.2 (M+1).sup.+. .sup.1H NMR (400 MHz, DMSO-d.sub.6) 8.34 (d, J=8.9 Hz, 1H), 7.68 (d, J=4.1 Hz, 1H), 7.17 (d, J=4.0 Hz, 1H), 4.00 (q, J=7.1 Hz, 2H), 3.95-3.85 (m, 2H), 3.46-3.38 (m, 1H), 2.76-2.58 (m, 2H), 1.71-1.54 (m, 3H), 1.51-1.43 (m, 2H), 1.15 (t, J=7.1 Hz, 3H), 1.09-1.00 (m, 1H), 0.97-0.87 (m, 2H), 0.50-0.42 (m, 1H), 0.38-0.25 (m, 2H), 0.20-0.13 (m, 1H).

Example 13: (S)-methyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropylethyl)piperidine-1-carboxylate

[0153] ##STR00040##

[0154] The title compound was prepared from (S)-5-chloro-N-(1-cyclopropyl-2-(piperidin-4-yl)ethyl)thiophene-2-carboxamide hydrochloride and methyl chloroformate in 50% yield as described herein for the synthesis of ethyl (S)-4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropyl ethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.17H.sub.23ClN.sub.2O.sub.3S: 370.1. Found: 371.3 (M+1).sup.+. .sup.1H NMR (400 MHz, DMSO-d.sub.6) 8.34 (d, J=8.8 Hz, 1H), 7.68 (d, J=4.1 Hz, 1H), 7.17 (d, J=4.0 Hz, 1H), 3.98-3.82 (m, 2H), 3.56 (s, 3H), 3.46-3.38 (m, 1H), 2.78-2.58 (m, 2H), 1.73-1.41 (m, 5H), 1.10-0.87 (m, 3H), 0.50-0.41 (m, 1H), 0.39-0.24 (m, 2H), 0.21-0.13 (m, 1H).

Example 14: isopropyl (S)-4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropylethyl)piperidine-1-carboxylate

[0155] ##STR00041##

[0156] The title compound was prepared from (S)-5-chloro-N-(1-cyclopropyl-2-(piperidin-4-yl)ethyl)thiophene-2-carboxamide hydrochloride and isopropyl chloroformate in 40% yield as described herein for the synthesis of ethyl (S)-4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropyl ethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.19H.sub.27ClN.sub.2O.sub.3S: 398.1. Found: 399.3 (M+1).sup.+. .sup.1H NMR (400 MHz, DMSO-d.sub.6) 8.34 (d, J=8.8 Hz, 1H), 7.68 (d, J=4.0 Hz, 1H), 7.17 (d, J=4.0 Hz, 1H), 4.78-4.67 (m, 1H), 4.00-3.81 (m, 2H), 3.47-3.37 (m, 1H), 2.79-2.58 (m, 2H), 1.71-1.43 (m, 5H), 1.16 (d, J=6.2 Hz, 6H), 1.08-0.89 (m, 3H), 0.50-0.42 (m, 1H), 0.39-0.24 (m, 2H), 0.21-0.14 (m, 1H).

Example 15: tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0157] ##STR00042##

Step 1: Preparation of tert-butyl 4-(2-(6-methoxypyridin-3-yl)-2-oxoethyl)piperidine-1-carboxylate

[0158] ##STR00043##

[0159] A solution of 5-bromo-2-methoxypyridine (0.55 ml, 4.25 mmol) in THE (10 ml) was cooled to 78 C., treated dropwise with 2.5M nBuLi/hexanes (1.70 ml, 4.25 mmol), and stirred at the same temperature for 1 hour. The reaction was treated slowly with a solution of tert-butyl 4-(2-(methoxy(methyl)amino)-2-oxoethyl)piperidine-1-carboxylate (1.00 g, 3.49 mmol) in THE (10 ml), and stirred for 1 hour while letting the bath slowly warm up. The bath was removed, and the reaction was stirred at RT for 15 minutes. The mixture was quenched with saturated NH4Cl, extracted with EtOAc, washed with brine, dried over Na.sub.2SO.sub.4, filtered, and concentrated. Purification by flash chromatography (silica gel, 0-70% EtOAc/hexanes, gradient elution) afforded the title compound (0.94 g, 80% yield) as light yellow oil that slowly crystallized. LCMS (ESI) m/z calcd for C.sub.18H.sub.26N.sub.2O.sub.4: 334.2. Found: 357.4 (M+23).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 8.78 (d, J=2.2 Hz, 1H), 8.14 (dd, J=2.5, 8.7 Hz, 1H), 6.80 (d, J=8.6 Hz, 1H), 4.18-3.96 (m, 5H), 2.83 (d, J=6.8 Hz, 2H), 2.75 (t, J=12.1 Hz, 2H), 2.22-2.08 (m, 1H), 1.73 (d, J=13.0 Hz, 2H), 1.46 (s, 9H), 1.31-1.12 (m, 2H).

Step 2: Preparation of tert-butyl 4-(2-amino-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate formic acid salt

[0160] ##STR00044##

[0161] A solution of tert-butyl 4-(2-(6-methoxypyridin-3-yl)-2-oxoethyl)piperidine-1-carboxylate (0.314 g, 0.939 mmol) in 2M ammonia/EtOH (7 mL, 14.0 mmol) was treated with titanium(IV) isopropoxide (1.10 mL, 3.76 mmol) and stirred at RT in a screw cap tube. After 18 hours, the reaction was treated with additional titanium(IV) isopropoxide (0.55 mL), stirred at RT for 1 hour, and then heated at 65 C. for 1 hour. The reaction was cooled to 0 C., treated with NaBH.sub.4 (53.3 mg, 1.41 mmol) and stirred at RT for 18 hours. The mixture was poured to aqueous NH.sub.4OH, diluted with EtOH, and stirred for 20 minutes at RT. The suspension was filtered and washed with EtOH, and then EtOAc. The filtrate was concentrated, the residue was diluted with water, extracted with EtOAc, washed with brine, dried over Na.sub.2SO.sub.4, filtered, and concentrated. Purification by reverse phase flash chromatography (ISCO C18 column, 5-55% MeCN/water with 0.1% formic acid) afforded the title compound as the formic acid salt (261 mg, 73% yield) as white solid. LCMS (ESI) m/z calcd for C.sub.18H.sub.29N.sub.3O.sub.3: 335.2. Found: 336.4 (M+1).sup.+. .sup.1H NMR (400 MHz, methanol-d.sub.4) 8.50 (br s, 1H), 8.23 (d, J=2.4 Hz, 1H), 7.78 (dd, J=2.5, 8.7 Hz, 1H), 6.90 (d, J=8.8 Hz, 1H), 4.39 (dd, J=5.7, 10.1 Hz, 1H), 4.02 (t, J=14.6 Hz, 2H), 3.93 (s, 3H), 2.78-2.48 (m, 2H), 2.02-1.81 (m, 2H), 1.76 (d, J=12.6 Hz, 1H), 1.61 (d, J=13.9 Hz, 1H), 1.52-1.38 (m, 9H), 1.37-1.23 (m, 1H), 1.22-1.03 (m, 2H).

Step 3: Preparation of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0162] ##STR00045##

[0163] A suspension of tert-butyl 4-(2-amino-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate formic acid salt (30 mg, 0.079 mmol) in DMF (1 mL) was treated with 5-chlorothiophene-2-carboxylic acid (15.3 mg, 0.094 mmol), DIEA (0.048 mL, 0.275 mmol), HATU (36 mg, 0.094 mmol), and stirred at RT for 2 hours. The reaction was treated with additional DIEA (50 uL), HATU (36 mg), and stirred at RT for another 45 minutes. The mixture was diluted with water, extracted with EtOAc, washed with water, brine, dried over Na.sub.2SO.sub.4, filtered, and concentrated. Purification by reverse phase HPLC (C18, 15-100% MeCN/water with 0.1% formic acid) afforded the title compound (12 mg, 31% yield) as a white solid. LCMS (ESI) m/z calcd for C.sub.23H.sub.30ClN.sub.3O.sub.4S: 479.2. Found: 478.5 (M1).sup.. .sup.1H NMR (400 MHz, DMSO-d.sub.6) 8.84 (d, J=8.4 Hz, 1H), 8.14 (d, J=2.2 Hz, 1H), 7.79-7.65 (m, 2H), 7.19 (d, J=4.0 Hz, 1H), 6.80 (d, J=8.4 Hz, 1H), 5.08-4.94 (m, 1H), 3.97-3.85 (m, 2H), 3.82 (s, 3H), 2.74-2.55 (m, 2H), 1.92-1.76 (m, 1H), 1.72-1.57 (m, 3H), 1.49-1.32 (m, 10H), 1.13-0.92 (m, 2H).

Example 16: tert-butyl (S)-4-(2-(5-chlorothiophene-2-carboxamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0164] ##STR00046##

[0165] The title compound (white solid) was prepared in 52% yield from tert-butyl (S)-4-(2-amino-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate and 5-chlorothiophene-2-carboxylic acid as described herein for the preparation of tert-butyl (S)-4-(2-(4-bromobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.23H.sub.30ClN.sub.3O.sub.4S: 479.2. Found: 480.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 8.17 (br s, 1H), 7.56 (d, J=8.2 Hz, 1H), 7.24 (br. s., 1H), 6.89 (br s, 1H), 6.75 (d, J=8.4 Hz, 1H), 6.01 (d, J=7.5 Hz, 1H), 5.19 (q, J=7.1 Hz, 1H), 4.21-3.99 (m, 2H), 3.93 (s, 3H), 2.74-2.50 (m, 2H), 1.99-1.65 (m, 4H), 1.55-1.33 (m, 10H), 1.30-1.05 (m, 2H).

Example 17: tert-butyl (S)-4-(2-(4-fluorobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0166] ##STR00047##

[0167] The title compound (white solid) was prepared in 36% yield from tert-butyl (S)-4-(2-amino-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate and 4-fluorobenzoic acid as described herein for the preparation of tert-butyl (S)-4-(2-(4-bromobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.25H.sub.32FN.sub.3O.sub.4: 457.2. Found: 458.4 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 8.19 (brs, 1H), 7.83-7.68 (m, 2H), 7.59 (dd, J=1.7, 8.3 Hz, 1H), 7.11 (t, J=8.4 Hz, 2H), 6.75 (d, J=8.4 Hz, 1H), 6.20 (d, J=7.7 Hz, 1H), 5.25 (q, J=7.6 Hz, 1H), 4.17-3.99 (m, 2H), 3.93 (s, 3H), 2.78-2.50 (m, 2H), 1.97-1.66 (m, 4H), 1.53-1.36 (m, 10H), 1.32-1.07 (m, 2H).

Example 18: tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-4-methylpentyl)piperidine-1-carboxylate

[0168] ##STR00048##

[0169] The title compound (white solid) was prepared in 4 steps from tert-butyl 4-(2-(methoxy(methyl)amino)-2-oxoethyl)piperidine-1-carboxylate and isobutylmagnesium bromide as described herein for the preparation of tert-butyl 4-(2-(5-ethylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.21H.sub.33ClN.sub.2O.sub.3S: 428.2. Found: 451.3 (M+23).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.23 (d, J=3.9 Hz, 1H), 6.90 (d, J=3.9 Hz, 1H), 5.43 (d, J=9.4 Hz, 1H), 4.37-4.22 (m, 1H), 4.20-3.92 (m, 2H), 2.80-2.54 (m, 2H), 1.88 (d, J=12.5 Hz, 1H), 1.72-1.54 (m, 1H), 1.54-1.25 (m, 15H), 1.22-1.00 (m, 2H), 0.99-0.85 (m, 6H).

Example 19: tert-butyl (S)-4-(2-(4-chlorobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0170] ##STR00049##

[0171] The title compound (white solid) was prepared in 31% yield from tert-butyl (S)-4-(2-amino-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate formic acid salt and 4-chlorobenzoic acid as described herein for the preparation of tert-butyl (S)-4-(2-(4-bromobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.25H.sub.32ClN.sub.3O.sub.4: 473.2. Found: 474.4 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 8.19 (d, J=2.3 Hz, 1H), 7.68 (d, J=8.6 Hz, 2H), 7.58 (dd, J=2.3, 8.6 Hz, 1H), 7.40 (d, J=8.6 Hz, 2H), 6.75 (d, J=8.6 Hz, 1H), 6.21 (d, J=7.8 Hz, 1H), 5.25 (q, J=7.8 Hz, 1H), 4.20-3.99 (m, 2H), 3.93 (s, 3H), 2.71-2.51 (m, 2H), 1.96-1.67 (m, 4H), 1.53-1.34 (m, 10H), 1.30-1.08 (m, 2H).

Example 20: tert-butyl(S)-4-(2-(6-methoxypyridin-3-yl)-2-(5-methylthiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0172] ##STR00050##

[0173] A mixture of tert-butyl (S)-4-(2-amino-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate formic acid salt (50 mg, 0.131 mmol) and 5-methylthiophene-2-carboxylic acid (28.0 mg, 0.197 mmol) in DMF (1.3 mL) was treated with DIEA (0.069 mL, 0.393 mmol), and then 50% T3P/EtOAc (0.117 mL, 0.197 mmol) slowly. After stirring for 4 hours at RT, the reaction was diluted with water and extracted with EtOAc. The EtOAc solution was washed with 1N HCl, saturated aqueous NaHCO.sub.3, water, brine, dried over Na.sub.2SO.sub.4, filtered, and concentrated. Purification by reverse phase HPLC (20-90% MeCN/water with 0.1% formic acid) afforded the titled compound (6.7 mg, 11% yield) as white solid. LCMS (ESI) m/z calcd for C.sub.24H.sub.33N.sub.3O.sub.4S: 459.2. Found: 460.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 8.17 (d, J=2.3 Hz, 1H), 7.57 (dd, J=2.3, 8.6 Hz, 1H), 7.30 (d, J=3.5 Hz, 1H), 6.78-6.69 (m, 2H), 5.93 (d, J=7.8 Hz, 1H), 5.21 (q, J=7.8 Hz, 1H), 4.19-3.97 (m, 2H), 3.93 (s, 3H), 2.74-2.55 (m, 2H), 2.51 (s, 3H), 1.94-1.67 (m, 4H), 1.53-1.36 (m, 10H), 1.30-1.07 (m, 2H).

Example 21: isopropyl (S)-4-(2-(5-chlorothiophene-2-carboxamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0174] ##STR00051##

[0175] The title compound was prepared in 86% yield from tert-butyl (S)-4-(2-(5-chlorothiophene-2-carboxamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate and isopropyl chloroformate as described herein for the preparation of phenyl (R)-4-(2-(5-chlorothiophene-2-carboxamido)propyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.22H.sub.28ClN.sub.3O.sub.4S: 465.2. Found: 466.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 8.17 (brs, 1H), 7.56 (d, J=7.8 Hz, 1H), 7.24 (br s, 1H), 6.89 (br s, 1H), 6.75 (d, J=8.6 Hz, 1H), 6.03 (d, J=7.0 Hz, 1H), 5.28-5.09 (m, 1H), 4.99-4.76 (m, 1H), 4.32-4.01 (m, 2H), 3.93 (br s, 3H), 2.80-2.50 (m, 2H), 1.93-1.67 (m, 4H), 1.42 (br s, 1H), 1.33-1.03 (m, 8H).

Example 22: isopropyl (S)-4-(2-(4-chlorobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0176] ##STR00052##

[0177] The title compound was prepared in 69% yield from tert-butyl (S)-4-(2-(4-chlorobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate and isopropyl chloroformate as described herein for the preparation of phenyl (R)-4-(2-(5-chlorothiophene-2-carboxamido)propyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.24H.sub.30ClN.sub.3O.sub.4: 459.2. Found: 460.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 8.19 (s, 1H), 7.68 (d, J=8.2 Hz, 2H), 7.58 (dd, J=2.0, 8.6 Hz, 1H), 7.40 (d, J=8.6 Hz, 2H), 6.75 (d, J=8.6 Hz, 1H), 6.22 (d, J=7.8 Hz, 1H), 5.24 (q, J=7.8 Hz, 1H), 4.97-4.79 (m, 1H), 4.27-4.01 (m, 2H), 3.93 (s, 3H), 2.77-2.54 (m, 2H), 1.96-1.68 (m, 4H), 1.52-1.36 (m, 1H), 1.32-1.09 (m, 8H).

Synthesis of Amine Intermediate (S)-tert-butyl 4-(2-amino-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0178] ##STR00053##

Step 1: Preparation of tert-butyl 4-((S)-2-(((S)-1-(4-methoxyphenyl)ethyl)amino)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0179] ##STR00054##

[0180] A suspension of tert-butyl 4-(2-(6-methoxypyridin-3-yl)-2-oxoethyl)piperidine-1-carboxylate (3.00 g, 8.97 mmol) and (S)-1-(4-methoxyphenyl)ethan-1-amine (2.00 mL, 13.5 mmol) in titanium(IV) isopropoxide (7.89 mL, 26.9 mmol) was stirred at 90 C. The reaction progress was monitored by LCMS (aliquots treated with MeOH, NaBH.sub.4, followed by 1N HCl). LCMS indicated complete reaction after 1 hour. The yellow solution was cooled to 0 C., diluted with MeOH (15 mL), treated slowly with NaBH.sub.4 (0.509 g, 13.46 mmol) in portions. After 1 hour, the solution was warmed to RT and stirred for an additional 4 hours. The reaction was quenched with saturated aqueous NH.sub.4Cl and 1N HCl and then extracted with EtOAc. The EtOAc solution was washed with saturated aqueous NaHCO.sub.3, brine, dried over Na.sub.2SO.sub.4, filtered, and concentrated. .sup.1H-NMR analysis of the crude material showed an approximately 2:1 mixture of SS: RS diastereomers. Purification by flash chromatography (silica gel, 0-100% EtOAc/hexanes, gradient elution) afforded tert-butyl 4-((S)-2-(((S)-1-(4-methoxyphenyl)ethyl)amino)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate (2.39 g, 57% yield) as clear oil. LCMS (ESI) m/z calcd for C.sub.27H.sub.39N.sub.3O.sub.4: 469.3. Found: 470.4 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.85 (s, 1H), 7.48 (d, J=8.6 Hz, 1H), 7.12 (d, J=8.2 Hz, 2H), 6.87 (d, J=8.2 Hz, 2H), 6.76 (d, J=8.6 Hz, 1H), 4.08-3.88 (m, 5H), 3.82 (s, 3H), 3.40 (q, J=6.4 Hz, 1H), 3.33 (t, J=6.6 Hz, 1H), 2.67-2.43 (m, 2H), 1.66-1.48 (m, 2H), 1.47-1.16 (m, 15H), 1.09-0.82 (m, 2H).

Step 2: Preparation of tert-butyl (S)-4-(2-amino-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0181] ##STR00055##

[0182] A solution of tert-butyl 4-((S)-2-(((S)-1-(4-methoxyphenyl)ethyl)amino)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate (2.38 g, 5.07 mmol) in MeOH (51 ml) under N.sub.2 was treated with 10% Pd/C (0.81 g). The mixture was subjected to hydrogenation at 60 psi and 60 C. for 18 hours. After cooling to RT, the mixture was purged with N.sub.2, filtered, washed with MeOH, and concentrated. The crude product was purified by flash chromatography (silica gel, 0-10% MeOH containing 1% NH.sub.4OH/DCM, gradient elution) to give the title compound (1.08 g, 64% yield) as clear oil. Chiral analytical HPLC indicated an enantiomeric purity of 95% [Chiralcel OZ-H column (4.6 mm250 mm, 5p); mobile phase: 3:7 EtOH/hexane+0.1% DEA; flow rate: 1 mL/min; injection volume: 6 uL (1 mg/mL conc.); monitored at 254 nm]. LCMS (ESI) m/z calcd for C.sub.18H.sub.29N.sub.3O.sub.3: 335.2. Found: 358.4 (M+23).sup.+. .sup.1H NMR (400 MHz, methanol-d.sub.4) 8.12 (d, J=2.0 Hz, 1H), 7.74 (dd, J=2.3, 8.6 Hz, 1H), 6.83 (d, J=8.6 Hz, 1H), 4.12 (t, J=7.6 Hz, 1H), 4.07-3.93 (m, 2H), 3.90 (s, 3H), 2.65 (br. s., 2H), 1.80-1.66 (m, 3H), 1.66-1.54 (m, 1H), 1.43 (s, 9H), 1.38-1.24 (m, 1H), 1.17-1.01 (m, 2H).

Example 23: tert-butyl (S)-4-(2-(4-bromobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0183] ##STR00056##

[0184] A solution of tert-butyl (S)-4-(2-amino-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate (50 mg, 0.149 mmol) in DMF (1.5 mL) was treated with 4-bromobenzoic acid (33.0 mg, 0.164 mmol), DIEA (0.078 mL, 0.447 mmol), HATU (85 mg, 0.224 mmol), and stirred at RT for 2 hours. The reaction was quenched with 2M NH.sub.3/MeOH and stirred for an additional 1.5 hours. The mixture was diluted with water and extracted with EtOAc. The EtOAc solution was washed with 1N HCl, saturated aqueous NaHCO.sub.3, brine, dried over Na.sub.2SO.sub.4, filtered, and concentrated. Purification by reverse phase HPLC (C18, 20-90% MeCN/water with 0.1% formic acid) afforded the title compound (60 mg, 77% yield) as white solid. LCMS (ESI) m/z calcd for C.sub.25H.sub.32BrN.sub.3O.sub.4: 517.2. Found: 518.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 8.19 (d, J=1.6 Hz, 1H), 7.69-7.48 (m, 5H), 6.75 (d, J=8.6 Hz, 1H), 6.22 (d, J=7.8 Hz, 1H), 5.24 (q, J=7.7 Hz, 1H), 4.25-3.98 (m, 2H), 3.93 (s, 3H), 2.74-2.48 (m, 2H), 1.96-1.68 (m, 4H), 1.53-1.34 (m, 10H), 1.31-1.06 (m, 2H).

Example 24: tert-butyl (S)-4-(2-(5-ethylthiophene-2-carboxamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0185] ##STR00057##

[0186] The title compound (white solid) was prepared in 89% yield from tert-butyl (S)-4-(2-amino-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate and 5-ethylthiophene-2-carboxylic acid as described herein for the preparation of tert-butyl (S)-4-(2-(4-bromobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.25H.sub.35N.sub.3O.sub.4S: 473.2. Found: 474.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 8.17 (d, J=2.0 Hz, 1H), 7.57 (dd, J=2.1, 8.4 Hz, 1H), 7.33 (d, J=3.5 Hz, 1H), 6.81-6.68 (m, 2H), 5.96 (d, J=8.2 Hz, 1H), 5.22 (q, J=7.8 Hz, 1H), 4.25-3.99 (m, 2H), 3.93 (s, 3H), 2.86 (q, J=7.4 Hz, 2H), 2.73-2.51 (m, 2H), 1.93-1.68 (m, 4H), 1.54-1.38 (m, 10H), 1.32 (t, J=7.6 Hz, 3H), 1.28-1.06 (m, 2H).

Example 25: tert-butyl (S)-4-(2-(5-fluorothiophene-2-carboxamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0187] ##STR00058##

[0188] The title compound (white solid) was prepared in 32% yield from tert-butyl (S)-4-(2-amino-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate and 5-fluorothiophene-2-carboxylic acid as described herein for the preparation of tert-butyl (S)-4-(2-(6-methoxypyridin-3-yl)-2-(5-methylthiophene-2-carboxamido)ethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.23H.sub.30FN.sub.3O.sub.4S: 463.2. Found: 462.2 (M1).sup.. .sup.1H NMR (400 MHz, CDCl.sub.3) 8.17 (br s, 1H), 7.56 (d, J=7.8 Hz, 1H), 7.11 (br s, 1H), 6.75 (d, J=8.6 Hz, 1H), 6.47 (d, J=3.5 Hz, 1H), 5.96 (d, J=7.4 Hz, 1H), 5.19 (q, J=7.3 Hz, 1H), 4.26-3.99 (m, 2H), 3.93 (s, 3H), 2.77-2.50 (m, 2H), 1.95-1.66 (m, 4H), 1.53-1.32 (m, 10H), 1.30-1.04 (m, 2H).

Synthesis of Amine Intermediate tert-butyl 4-(2-amino-4-methylpentyl)piperidine-1-carboxylate

[0189] ##STR00059##

[0190] The title compound was prepared in 3 steps from tert-butyl 4-(2-(methoxy(methyl)amino)-2-oxoethyl)piperidine-1-carboxylate and isobutylmagnesium bromide as described herein for the preparation of tert-butyl 4-(2-amino-2-phenylethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.16H.sub.32N.sub.2O.sub.2: 284.3. Found: 307.4 (M+23).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 4.27-3.87 (m, 2H), 2.98-2.85 (m, 1H), 2.79-2.61 (m, 2H), 1.80-1.68 (m, 2H), 1.66-1.52 (m, 2H), 1.46 (s, 9H), 1.33-1.19 (m, 4H), 1.18-0.99 (m, 2H), 0.96-0.83 (m, 6H).

Example 26: tert-butyl 4-(4-methyl-2-(5-methylthiophene-2-carboxamido)pentyl)piperidine-1-carboxylate

[0191] ##STR00060##

[0192] The title compound (white solid) was prepared from tert-butyl 4-(2-amino-4-methylpentyl)piperidine-1-carboxylate and 5-methylthiophene-2-carboxylic acid as described herein for the preparation of tert-butyl 4-(2-(5-ethylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate from tert-butyl 4-(2-amino-2-phenylethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.22H.sub.36N.sub.2O.sub.3S: 408.2. Found: 407.5 (M1).sup.. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.30 (d, J=3.5 Hz, 1H), 6.74 (d, J=3.1 Hz, 1H), 5.43 (d, J=9.4 Hz, 1H), 4.38-4.21 (m, 1H), 4.17-3.91 (m, 2H), 2.77-2.58 (m, 2H), 2.51 (s, 3H), 1.90 (d, J=12.5 Hz, 1H), 1.72-1.54 (m, 3H), 1.53-1.23 (m, 13H), 1.21-1.00 (m, 2H), 1.00-0.84 (m, 6H).

Example 27: tert-butyl 4-(2-(4-bromobenzamido)-4-methylpentyl)piperidine-1-carboxylate

[0193] ##STR00061##

[0194] The title compound (white solid) was prepared from tert-butyl 4-(2-amino-4-methylpentyl)piperidine-1-carboxylate and 4-bromobenzoic acid as described herein for the preparation of tert-butyl 4-(2-(5-ethylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate from tert-butyl 4-(2-amino-2-phenylethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.23H.sub.35BrN.sub.2O.sub.3: 466.2. Found: 467.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.67-7.54 (m, 4H), 5.69 (d, J=9.4 Hz, 1H), 4.44-4.26 (m, 1H), 4.16-3.92 (m, 2H), 2.76-2.55 (m, 2H), 1.96-1.85 (m, 1H), 1.75-1.55 (m, 3H), 1.54-1.30 (m, 13H), 1.23-1.02 (m, 2H), 1.00-0.88 (m, 6H).

Example 28: tert-butyl 4-(2-(5-bromothiophene-2-carboxamido)-4-methylpentyl)piperidine-1-carboxylate

[0195] ##STR00062##

[0196] The title compound (white solid) was prepared from tert-butyl 4-(2-amino-4-methylpentyl)piperidine-1-carboxylate and 5-bromothiophene-2-carboxylic acid as described herein for the preparation of tert-butyl 4-(2-(5-ethylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate from tert-butyl 4-(2-amino-2-phenylethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.21H.sub.33BrN.sub.2O.sub.3S: 472.1. Found: 471.2 (M1).sup.. .sup.1H NMR (400 MHz, methanol-d.sub.4) 7.48 (d, J=3.9 Hz, 1H), 7.14 (d, J=3.9 Hz, 1H), 4.31-4.15 (m, 1H), 4.08-3.94 (m, 2H), 2.82-2.55 (m, 2H), 1.97-1.84 (m, 1H), 1.67-1.56 (m, 2H), 1.55-1.23 (m, 14H), 1.19-0.95 (m, 2H), 0.95-0.83 (m, 6H).

Example 29: tert-butyl (S)-4-(2-(5-bromothiophene-2-carboxamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0197] ##STR00063##

[0198] The title compound (white solid) was prepared in 70% yield from tert-butyl (S)-4-(2-amino-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate and 5-bromothiophene-2-carboxylic acid as described herein for the preparation of tert-butyl (S)-4-(2-(4-bromobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.23H.sub.30BrN.sub.3O.sub.4S: 523.1. Found: 522.15 (M1).sup.. .sup.1H NMR (400 MHz, methanol-d.sub.4) 8.12 (d, J=2.3 Hz, 1H), 7.70 (dd, J=2.7, 8.6 Hz, 1H), 7.53 (d, J=3.9 Hz, 1H), 7.15 (d, J=3.9 Hz, 1H), 6.78 (d, J=8.6 Hz, 1H), 5.19-5.09 (m, 1H), 4.09-3.98 (m, 2H), 3.88 (s, 3H), 2.80-2.57 (m, 2H), 1.99-1.87 (m, 1H), 1.83-1.66 (m, 3H), 1.57-1.46 (m, 1H), 1.43 (s, 9H), 1.24-1.06 (m, 2H).

Example 30: tert-butyl (S)-4-(2-(5-ethylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0199] ##STR00064##

[0200] The title compound (white solid) was prepared in 3 steps from tert-butyl (S,E)-4-(2-((tert-butylsulfinyl)imino)ethyl)piperidine-1-carboxylate and phenylmagnesium bromide as described herein for the preparation of tert-butyl (R)-4-(2-(5-chlorothiophene-2-carboxamido)propyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.25H.sub.34N.sub.2O.sub.3S: 442.2. Found: 443.4 (M+1). .sup.1H NMR (400 MHz, CDCl.sub.3) 7.42-7.23 (m, 6H), 6.76 (d, J=3.5 Hz, 1H), 5.99 (d, J=8.2 Hz, 1H), 5.27 (q, J=7.8 Hz, 1H), 4.18-3.93 (m, 2H), 2.85 (q, J=7.7 Hz, 2H), 2.74-2.51 (m, 2H), 1.94-1.67 (m, 4H), 1.45 (s, 10H), 1.35-1.05 (m, 5H).

Example 31: tert-butyl 4-(2-(5-bromothiophene-2-carboxamido)-2-cyclohexylethyl)piperidine-1-carboxylate

[0201] ##STR00065##

[0202] The title compound (white solid) was prepared in 4 steps from tert-butyl 4-(2-(methoxy(methyl)amino)-2-oxoethyl)piperidine-1-carboxylate and cyclohexylmagnesium chloride as described herein for the preparation of tert-butyl 4-(2-(5-ethylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate LCMS (ESI) m/z calcd for C.sub.23H.sub.35BrN.sub.2O.sub.3S: 498.2. Found: 499.3 (M+1).sup.+. .sup.1H NMR (400 MHz, methanol-d.sub.4) 8.07 (d, J=9.4 Hz, 1H), 7.51 (d, J=3.9 Hz, 1H), 7.14 (d, J=4.3 Hz, 1H), 4.09-3.88 (m, 3H), 2.81-2.52 (m, 2H), 1.92-1.70 (m, 5H), 1.69-1.36 (m, 15H), 1.34-0.89 (m, 7H).

Example 32: isopropyl (S)-4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0203] ##STR00066##

Preparation of tert-butyl (S)-4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0204] ##STR00067##

[0205] The title compound (white solid) was prepared in 3 steps from tert-butyl (S,E)-4-(2-((tert-butylsulfinyl)imino)ethyl)piperidine-1-carboxylate and phenylmagnesium bromide as described herein for the preparation (S)-tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropylethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.25H.sub.31ClN.sub.2O.sub.3: 442.2. Found: 443.4 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.69 (d, J=7.8 Hz, 2H), 7.47-7.29 (m, 7H), 6.21 (d, J=7.8 Hz, 1H), 5.30 (q, J=7.8 Hz, 1H), 4.16-3.96 (m, 2H), 2.75-2.47 (m, 2H), 1.98-1.69 (m, 4H), 1.50-1.33 (m, 10H), 1.24-1.03 (m, 2H).

Preparation of isopropyl (S)-4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0206] ##STR00068##

[0207] The title compound was prepared in 54% yield from tert-butyl (S)-4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate and isopropyl chloroformate as described herein for the preparation of ethyl (S)-4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropyl ethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.24H.sub.29ClN.sub.2O.sub.3: 428.2. Found: 429.4 (M+1).sup.+. .sup.1H NMR (400 MHz, methanol-d.sub.4) 7.80 (d, J=8.6 Hz, 2H), 7.47 (d, J=8.2 Hz, 2H), 7.41-7.35 (m, 2H), 7.32 (t, J=7.6 Hz, 2H), 7.26-7.19 (m, 1H), 5.23 (dd, J=5.9, 9.8 Hz, 1H), 4.86-4.77 (m, 1H), 4.14-3.93 (m, 2H), 2.89-2.57 (m, 2H), 2.00-1.65 (m, 4H), 1.61-1.46 (m, 1H), 1.30-1.06 (m, 8H).

Example 33: isopropyl (S)-4-(2-(5-ethylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0208] ##STR00069##

[0209] The title compound (white solid) was prepared in 67% yield from tert-butyl (S)-4-(2-(5-ethylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate and isopropyl chloroformate as described herein for the preparation of ethyl (S)-4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropyl ethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.24H.sub.32N.sub.2O.sub.3S: 428.2. Found: 429.3 (M+1).sup.+. .sup.1H NMR (400 MHz, methanol-d.sub.4) 7.59 (d, J=3.9 Hz, 1H), 7.41-7.26 (m, 4H), 7.26-7.17 (m, 1H), 6.83 (d, J=3.5 Hz, 1H), 5.18 (dd, J=5.7, 10.0 Hz, 1H), 4.86-4.75 (m, 1H), 4.15-3.99 (m, 2H), 2.85 (q, J=7.5 Hz, 2H), 2.79-2.58 (m, 2H), 2.00-1.64 (m, 4H), 1.63-1.48 (m, 1H), 1.30 (t, J=7.4 Hz, 3H), 1.25-1.04 (m, 8H).

Example 34: tert-butyl (R)-4-(2-(5-chlorothiophene-2-carboxamido)pent-4-en-1-yl)piperidine-1-carboxylate

[0210] ##STR00070##

[0211] The title compound (white solid) was prepared in 3 steps from tert-butyl (S,E)-4-(2-((tert-butylsulfinyl)imino)ethyl)piperidine-1-carboxylate and allylmagnesium bromide as described herein for the preparation of (S)-tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropylethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.20H.sub.29ClN.sub.2O.sub.3S: 412.2. Found: 411.2 (M1).sup.. .sup.1H NMR (400 MHz, methanol-d.sub.4) 7.52 (d, J=3.9 Hz, 1H), 7.01 (d, J=3.9 Hz, 1H), 5.88-5.72 (m, 1H), 5.12-4.96 (m, 2H), 4.23-4.13 (m, 1H), 4.06-3.95 (m, 2H), 2.84-2.53 (m, 2H), 2.37-2.17 (m, 2H), 1.90-1.78 (m, 1H), 1.67-1.57 (m, 1H), 1.57-1.37 (m, 12H), 1.18-0.93 (m, 2H).

Example 35: phenyl 4-(2-(5-chlorothiophene-2-carboxamido)-4-methylpentyl)piperidine-1-carboxylate

[0212] ##STR00071##

[0213] The title compound (white solid) was prepared in 77% yield from tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-4-methylpentyl)piperidine-1-carboxylate and phenyl chloroformate as described herein for the preparation of ethyl (S)-4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropyl ethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.23H.sub.29ClN.sub.2O.sub.3S: 448.2. Found: 449.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.43-7.31 (m, 2H), 7.25 (d, J=3.9 Hz, 1H), 7.23-7.15 (m, 1H), 7.10 (d, J=7.8 Hz, 2H), 6.92 (d, J=3.9 Hz, 1H), 5.44 (d, J=9.0 Hz, 1H), 4.41-4.15 (m, 3H), 3.04-2.65 (m, 2H), 2.11-1.90 (m, 1H), 1.77-1.63 (m, 2H), 1.51-1.13 (m, 7H), 1.02-0.88 (m, 6H).

Example 36: phenyl (S)-4-(2-(5-chlorothiophene-2-carboxamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0214] ##STR00072##

[0215] The title compound (off-white solid) was prepared in 74% yield from tert-butyl (S)-4-(2-(5-chlorothiophene-2-carboxamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate and phenyl chloroformate as described herein for the preparation of ethyl (S)-4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropyl ethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.25H.sub.26ClN.sub.3O.sub.4S: 499.1. Found: 498.3 (M1).sup.. .sup.1H NMR (400 MHz, methanol-d.sub.4) 8.15 (d, J=2.3 Hz, 1H), 7.73 (dd, J=2.3, 8.6 Hz, 1H), 7.60 (d, J=3.9 Hz, 1H), 7.42-7.31 (m, 2H), 7.25-7.15 (m, 1H), 7.11-7.00 (m, 3H), 6.80 (d, J=8.6 Hz, 1H), 5.25-5.11 (m, 1H), 4.38-4.06 (m, 2H), 3.89 (s, 3H), 3.06-2.71 (m, 2H), 2.06-1.71 (m, 4H), 1.67-1.53 (m, 1H), 1.45-1.18 (m, 2H).

Example 37: phenyl (S)-4-(2-(4-chlorobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0216] ##STR00073##

[0217] The title compound (off-white solid) was prepared in 68% yield from tert-butyl (S)-4-(2-(4-chlorobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate and phenyl chloroformate as described herein for the preparation of ethyl (S)-4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropyl ethyl)piperidine-1-carboxylate. LCMS (ESI) m/z calcd for C.sub.27H.sub.28ClN.sub.3O.sub.4: 493.2. Found: 494.3 (M+1).sup.+. .sup.1H NMR (400 MHz, methanol-d.sub.4) 8.18 (d, J=2.3 Hz, 1H), 7.82 (d, J=8.6 Hz, 2H), 7.76 (dd, J=2.3, 8.6 Hz, 1H), 7.49 (d, J=8.6 Hz, 2H), 7.41-7.32 (m, 2H), 7.26-7.17 (m, 1H), 7.07 (d, J=7.4 Hz, 2H), 6.81 (d, J=8.6 Hz, 1H), 5.32-5.20 (m, 1H), 4.37-4.06 (m, 2H), 3.90 (s, 3H), 3.08-2.76 (m, 2H), 2.07-1.74 (m, 4H), 1.72-1.54 (m, 1H), 1.45-1.19 (m, 2H).

Example 38: tert-butyl (R)-4-(2-(5-chlorothiophene-2-carboxamido)propyl)piperidine-1-carboxylate

[0218] ##STR00074##

Step 1: Preparation of tert-butyl 4-((R)-2-(((S)-tert-butylsulfinyl)amino)propyl)piperidine-1-carboxylate

[0219] ##STR00075##

[0220] A solution of tert-butyl (S,E)-4-(2-((tert-butylsulfinyl)imino)ethyl)piperidine-1-carboxylate (250 mg, 0.756 mmol) in DCM (19 mL) was treated dropwise with 3M methylmagnesium chloride/THF (0.328 mL, 0.983 mmol), and stirred at RT for 6 hours. The reaction was quenched with saturated aqueous NH.sub.4Cl and extracted with DCM. The DCM solution was washed with water, brine, dried over Na.sub.2SO.sub.4, filtered, and concentrated. Purification by flash chromatography twice (silica gel, 0-10% MeOH/DCM; then 0-100% acetone/hexanes, gradient elution) afforded the title compound (102 mg, 0.293 mmol, 39% yield) as white solid. LCMS (ESI) m/z calcd for C.sub.17H.sub.34N.sub.2O.sub.3S: 346.2. Found: 347.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 4.23-3.90 (m, 2H), 3.54-3.36 (m, 1H), 2.82 (d, J=8.2 Hz, 1H), 2.74-2.55 (m, 2H), 1.73-1.64 (m, 1H), 1.64-1.54 (m, 3H), 1.51-1.41 (m, 10H), 1.34-1.19 (m, 12H), 1.19-1.00 (m, 2H).

Step 2: Preparation of tert-butyl (R)-4-(2-aminopropyl)piperidine-1-carboxylate hydrochloride

[0221] ##STR00076##

[0222] An ice cold solution of tert-butyl 4-((R)-2-(((S)-tert-butylsulfinyl)amino)propyl)piperidine-1-carboxylate (100 mg, 0.289 mmol) in MeOH (1.6 mL) was treated dropwise with 4M HCl/dioxane (0.072 mL, 0.289 mmol). The mixture was stirred in the ice bath for 5 hours, letting the bath to warm up to RT. The reaction was concentrated to dryness and the residue co-evaporated with MeCN, and dried under vacuum to give the title compound as a white solid in quantitative yield. LCMS (ESI) m/z calcd for C.sub.13H.sub.26N.sub.2O.sub.2: 242.2. Found 243.3 (M+1).sup.+. .sup.1H NMR (400 MHz, methanol-d.sub.4) 4.15-3.96 (m, 2H), 3.42-3.33 (m, 1H), 2.88-2.60 (m, 2H), 1.79-1.65 (m, 2H), 1.64-1.42 (m, 12H), 1.29 (d, J=6.6 Hz, 3H), 1.16-1.01 (m, 2H).

Step 3: Preparation of tert-butyl (R)-4-(2-(5-chlorothiophene-2-carboxamido)propyl)piperidine-1-carboxylate

[0223] ##STR00077##

[0224] A solution of tert-butyl (R)-4-(2-aminopropyl)piperidine-1-carboxylate hydrochloride (80 mg, 0.29 mmol) in DMF (2.9 mL) was treated with 5-chlorothiophene-2-carboxylic acid (51.3 mg, 0.316 mmol), DIEA (0.200 mL, 1.15 mmol), HATU (164 mg, 0.430 mmol), and stirred at RT for 18 hours. The reaction was quenched with 2M NH.sub.3/MeOH and stirred for an additional 2 hours. The mixture was diluted with water and extracted with EtOAc. The EtOAc solution was washed with 1N HCl, saturated aqueous NaHCO.sub.3, brine, dried over Na.sub.2SO.sub.4, filtered, and concentrated. Purification by flash chromatography (0-80% EtOAc/hexanes) afforded the title compound (90 mg, 77% yield) as white solid. LCMS (ESI) m/z calcd for C.sub.18H.sub.27ClN.sub.2O.sub.3S: 386.1. Found: 385.4 (M1).sup.. .sup.1H NMR (400 MHz, methanol-d.sub.4) 7.52 (d, J=3.9 Hz, 1H), 7.00 (d, J=4.3 Hz, 1H), 4.27-4.13 (m, 1H), 4.07-3.96 (m, 2H), 2.84-2.56 (m, 2H), 1.86-1.75 (m, 1H), 1.69-1.31 (m, 13H), 1.19 (d, J=6.2 Hz, 3H), 1.17-0.96 (m, 2H).

Example 39: (S)-5-chloro-N-(2-(1-(3,3-dimethylbutanoyl)piperidin-4-yl)-1-(6-methoxypyridin-3-yl)ethyl)thiophene-2-carboxamide

[0225] ##STR00078##

Step 1: Preparation of (S)-5-chloro-N-(1-(6-methoxypyridin-3-yl)-2-(piperidin-4-yl)ethyl)thiophene-2-carboxamidehydrochloride

[0226] ##STR00079##

[0227] A solution of tert-butyl (S)-4-(2-(5-chlorothiophene-2-carboxamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate (260 mg, 0.542 mmol) in 1,4-dioxane (3.60 mL) and MeOH (1.8 mL) was treated with 4M HCl/dioxane (0.677 mL, 2.71 mmol) and stirred at RT for 18 hours. The mixture was concentrated to dryness at reduced pressure to afford the title compound as a white solid in quantitative yield. LCMS (ESI) m/z calcd for C.sub.18H.sub.22ClN.sub.3O.sub.2S: 379.1. Found: 380.2 (M+1).sup.+.

Step 2: Preparation of (S)-5-chloro-N-(2-(1-(3,3-dimethylbutanoyl)piperidin-4-yl)-1-(6-methoxypyridin-3-yl)ethyl)thiophene-2-carboxamide

[0228] ##STR00080##

[0229] An ice cold solution of (S)-5-chloro-N-(1-(6-methoxypyridin-3-yl)-2-(piperidin-4-yl)ethyl)thiophene-2-carboxamide hydrochloride (55 mg, 0.110 mmol) in DCM (1.1 mL) was treated with TEA (0.046 mL, 0.33 mmol), followed by a solution of 3,3-dimethylbutanoyl chloride (0.018 mL, 0.132 mmol) in DCM (0.5 mL) dropwise. The reaction was warmed to RT for 2.5 hours, diluted with water, and extracted with DCM. The DCM solution was washed with brine, dried over Na.sub.2SO.sub.4, filtered, and concentrated. Purification by reverse phase HPLC (C18, 30-100% MeCN/water with 0.1% formic acid) afforded the title compound (34 mg, 62% yield) as white solid. LCMS (ESI) m/z calcd for C.sub.24H.sub.32ClN.sub.3O.sub.3S: 477.2. Found: 478.3 (M+1).sup.+. .sup.1H NMR (400 MHz, methanol-d.sub.4) 8.13 (s, 1H), 7.71 (d, J=8.6 Hz, 1H), 7.63-7.55 (m, 1H), 7.07-6.96 (m, 1H), 6.79 (d, J=8.6 Hz, 1H), 5.22-5.11 (m, 1H), 4.63-4.48 (m, 1H), 4.12-3.98 (m, 1H), 3.88 (s, 3H), 3.10-2.95 (m, 1H), 2.54 (q, J=12.8 Hz, 1H), 2.42-2.18 (m, 2H), 2.04-1.50 (m, 5H), 1.33-1.07 (m, 2H), 1.02 (s, 9H).

Example 40: (S)-N-(tert-butyl)-4-(2-(5-chlorothiophene-2-carboxamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxamide

[0230] ##STR00081##

[0231] A solution of (S)-5-chloro-N-(1-(6-methoxypyridin-3-yl)-2-(piperidin-4-yl)ethyl)thiophene-2-carboxamide hydrochloride (55 mg, 0.110 mmol) in DCM (1.1 mL) was treated with TEA (0.061 mL, 0.44 mmol), followed by a solution of t-butyl isocyanate (0.025 mL, 0.22 mmol) in DCM (0.5 mL) dropwise. The reaction was stirred at RT for 3 hours, diluted with water and 1N HCl and extracted with DCM. The DCM solution was washed with saturated aqueous NaHCO.sub.3, brine, dried over Na.sub.2SO.sub.4, filtered, and concentrated. Purification by reverse phase HPLC (C18, 30-100% MeCN/water with 0.1% formic acid) afforded the title compound (28 mg, 50% yield) as white solid. LCMS (ESI) m/z calcd for C.sub.23H.sub.31ClN.sub.4O.sub.3S: 478.2. Found: 479.4 (M+1).sup.+. .sup.1H NMR (400 MHz, methanol-d.sub.4) 8.12 (d, J=2.3 Hz, 1H), 7.70 (dd, J=2.7, 8.6 Hz, 1H), 7.58 (d, J=3.9 Hz, 1H), 7.02 (d, J=3.9 Hz, 1H), 6.78 (d, J=8.6 Hz, 1H), 5.58 (s, 1H), 5.19-5.10 (m, 1H), 4.00-3.90 (m, 2H), 3.88 (s, 3H), 2.74-2.56 (m, 2H), 2.01-1.86 (m, 1H), 1.83-1.64 (m, 3H), 1.57-1.42 (m, 1H), 1.30 (s, 9H), 1.26-1.07 (m, 2H).

Example 41: (S)-5-chloro-N-(2-(1-(isobutylsulfonyl)piperidin-4-yl)-1-(6-methoxypyridin-3-yl)ethyl)thiophene-2-carboxamide

[0232] ##STR00082##

[0233] An ice cold solution of (S)-5-chloro-N-(1-(6-methoxypyridin-3-yl)-2-(piperidin-4-yl)ethyl)thiophene-2-carboxamide hydrochloride (55 mg, 0.110 mmol) in DCM (1.1 mL) was treated with TEA (0.046 mL, 0.33 mmol), followed by a solution of isobutanesulfonyl chloride (0.029 mL, 0.22 mmol) in DCM (0.5 mL) dropwise. The reaction was warmed to RT for 3.5 hours, treated with additional isobutanesulfonyl chloride (25 uL), stirred at 40 C. for 1 hour, and then cooled to RT overnight. The mixture was diluted with water and extracted with DCM The DCM solution was washed with brine, dried over Na.sub.2SO.sub.4, filtered, and concentrated. Purification by reverse phase HPLC (C18, 30-100% MeCN/water with 0.1% formic acid) afforded the title compound (28 mg, 50% yield) as a white solid. LCMS (ESI) m/z calcd for C.sub.22H.sub.30ClN.sub.3O.sub.4S.sub.2: 499.1. Found: 500.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 8.17 (d, J=1.6 Hz, 1H), 7.56 (dd, J=2.0, 8.6 Hz, 1H), 7.23 (d, J=3.9 Hz, 1H), 6.89 (d, J=3.5 Hz, 1H), 6.75 (d, J=8.6 Hz, 1H), 5.96 (d, J=8.2 Hz, 1H), 5.20 (q, J=7.7 Hz, 1H), 3.93 (s, 3H), 3.84-3.67 (m, 2H), 2.77-2.54 (m, 4H), 2.34-2.18 (m, 1H), 2.00-1.74 (m, 4H), 1.49-1.29 (m, 3H), 1.09 (d, J=6.6 Hz, 6H).

Example 42: phenyl (R)-4-(2-(5-chlorothiophene-2-carboxamido)propyl)piperidine-1-carboxylate

[0234] ##STR00083##

[0235] A solution of tert-butyl (R)-4-(2-(5-chlorothiophene-2-carboxamido)propyl)piperidine-1-carboxylate (56 mg, 0.145 mmol) in 1,4-dioxane (1 mL) and MeOH (0.5 mL) was treated with 4M HCl/dioxane (0.181 mL, 0.724 mmol), stirred at RT for 5 hours and then concentrated to dryness at reduced pressure. The residue was suspended in DCM (1 mL). The mixture was treated with TEA (0.061 mL, 0.43 mmol), followed by phenyl chloroformate (0.027 mL, 0.22 mmol). After stirring at RT for 30 minutes, the mixture was diluted with water and extracted with DCM. The DCM solution was washed with brine, dried over Na.sub.2SO.sub.4, filtered, and concentrated. Purification by reverse phase HPLC (C18, 30-100% MeCN/water with 0.1% formic acid) afforded the title compound (44 mg, 72% yield) as white solid. LCMS (ESI) m/z calcd for C.sub.20H.sub.23ClN.sub.2O.sub.3S: 406.1. Found: 407.3 (M+1).sup.+. .sup.1H NMR (400 MHz, methanol-d.sub.4) 8.24 (d, J=8.6 Hz, 1H), 7.54 (d, J=3.9 Hz, 1H), 7.41-7.30 (m, 2H), 7.25-7.15 (m, 1H), 7.06 (d, J=7.8 Hz, 2H), 7.01 (d, J=4.3 Hz, 1H), 4.36-4.06 (m, 3H), 3.08-2.74 (m, 2H), 1.98-1.85 (m, 1H), 1.81-1.69 (m, 1H), 1.67-1.52 (m, 2H), 1.49-1.39 (m, 1H), 1.36-1.06 (m, 5H).

Example 43: (S)-5-chloro-N-(2-(1-(2,2-difluoro-2-phenylacetyl)piperidin-4-yl)-1-(6-methoxypyridin-3-yl)ethyl)thiophene-2-carboxamide

[0236] ##STR00084##

[0237] A solution of (S)-5-chloro-N-(1-(6-methoxypyridin-3-yl)-2-(piperidin-4-yl)ethyl)thiophene-2-carboxamide hydrochloride (40 mg, 0.080 mmol) in DMF (0.8 mL) was treated with 2,2-difluoro-2-phenylacetic acid (15 mg, 0.088 mmol), DIEA (0.042 mL, 0.24 mmol), HATU (46 mg, 0.120 mmol), and stirred at RT for 3.5 hours. The reaction was quenched with 2M NH.sub.3/MeOH and stirred for an additional 45 min. The mixture was diluted with water and extracted with EtOAc. The EtOAc solution was washed with 1N HCl, saturated aqueous NaHCO.sub.3, brine, dried over Na.sub.2SO.sub.4, filtered, and concentrated. Purification by reverse phase HPLC (C18, 30-100% MeCN/water with 0.1% formic acid) afforded the title compound (24 mg, 55% yield) as white solid. LCMS (ESI) m/z calcd for C.sub.26H.sub.26ClF.sub.2N.sub.3O.sub.3S: 533.1. Found: 534.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 8.14 (brs, 1H), 7.64-7.38 (m, 6H), 7.22 (d, J=3.5 Hz, 1H), 6.88 (d, J=3.9 Hz, 1H), 6.75 (d, J=8.6 Hz, 1H), 5.96 (br s, 1H), 5.26-5.04 (m, 1H), 4.73-4.46 (m, 1H), 4.06-3.79 (m, 4H), 2.91-2.50 (m, 2H), 1.96-1.67 (m, 4H), 1.56-1.38 (m, 1H), 1.34-1.09 (m, 1H), 1.07-0.76 (m, 1H).

Example 44: tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-(diethylamino)-1,3,4-oxadiazol-2-yl)ethyl)piperidine-1-carboxylate

[0238] ##STR00085## ##STR00086##

Step 1: Preparation of tert-butyl 4-(hydroxymethyl)piperidine-1-carboxylate

[0239] ##STR00087##

[0240] To an ice cold solution of 1-(tert-butoxycarbonyl)piperidine-4-carboxylic acid (5.00 g, 21.8 mmol) in THF (50 mL) was slowly added 1M BH.sub.3-THF in THF (32.7 mL, 32.7 mmol) and the mixture was allowed to stir at 0 C. for 2 hours after which time TLC (10% MeOH/DCM, KMnO.sub.4 stain) indicated complete reaction. MeOH (5 mL) was added dropwise and the mixture was stirred at ambient temperature for 10 minutes. Saturated NaHCO.sub.3 (50 mL) was added and the mixture was extracted with EtOAc. The extracts were washed with brine, dried over Na.sub.2SO.sub.4, filtered and concentrated to afford the title compound as a viscous colorless oil (3.53 g, 75% yield). .sup.1H NMR (400 MHz, DMSO-d.sub.6) 4.45 (t, J=5.3 Hz, 1H), 4.00-3.85 (m, 2H), 3.23 (t, J=5.8 Hz, 2H), 2.79-2.53 (m, 2H), 1.66-1.56 (m, 2H), 1.55-1.44 (m, 1H), 1.43-1.33 (m, 9H), 1.01-0.90 (m, 2H).

Step 2: Preparation of tert-butyl 4-(iodomethyl)piperidine-1-carboxylate

[0241] ##STR00088##

[0242] To a stirred solution of tert-butyl 4-(hydroxymethyl)piperidine-1-carboxylate (3.53 g, 16.4 mmol), triphenylphosphine (6.86 g, 26.2 mmol) and imidazole (1.78 g, 26.2 mmol) in DCM (100 mL) at 0 C. was added iodine (6.64 g, 26.2 mmol). The mixture was stirred at 0 C. for 5 minutes, then warmed to ambient temperature and stirred overnight (excluded from light by wrapping vessel in aluminum foil after removing from ice bath). The yellow-brown reaction mixture was diluted with hexanes (200 mL) and the triphenylphosphine-oxide precipitate was filtered off. Hexanes (200 mL) was added to the filtrate (some additional precipitate and a reddish-brown oily residue was observed) and the mixture was filtered once more to remove the solids. The filtrate was concentrated and the residue was purified by flash chromatography (silica gel, 0-40% EtOAc/hexanes, gradient elution) to afford the title compound as a colorless oil (3.96 g, 74% yield). .sup.1H NMR (400 MHz, CDCl.sub.3) 4.34-3.95 (m, 2H), 3.10 (d, J=6.4 Hz, 2H), 2.69 (t, J=12.0 Hz, 2H), 1.83 (d, J=13.2 Hz, 2H), 1.69-1.54 (m, 1H), 1.46 (s, 9H), 1.14 (dq, J=4.2, 12.3 Hz, 2H).

Step 3: Preparation of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-3-ethoxy-3-oxopropyl)piperidine-1-carboxylate

[0243] ##STR00089##

[0244] To a solution of ethyl 2-((diphenylmethylene)amino)acetate (2.60 g, 9.73 mmol) in THE (60 mL) at 78 C. was added 1M potassium bis(trimethylsilyl)amide/THF (12.16 mL, 12.16 mmol) and the resulting yellow solution was stirred at 78 C. for 30 minutes. A solution of tert-butyl 4-(iodomethyl)piperidine-1-carboxylate (3.95 g, 12.16 mmol) in THE (15 mL) was slowly added. The reaction mixture was stirred at 78 C. for 30 minutes, 0 C. for one hour and then warmed to ambient temperature and stirred overnight. A solution of citric acid (2.34 g, 12.2 mmol) in water (100 mL) was added and the mixture was diluted with EtOAc. The mixture was partitioned and separated. The aqueous phase was further extracted with EtOAc and the combined organic phases were dried over MgSO.sub.4, filtered and concentrated. The residue was purified by flash chromatography (silica gel, 0-50% EtOAc/hexanes, gradient elution) to afford a pale yellow residue (3.6 g). The purified residue was dissolved in ethanol (80 mL), treated with 50 wt % aqueous hydroxylamine (2.50 mL, 40.8 mmol), stirred for 5 minutes and then treated with acetic acid (2.50 mL, 43.7 mmol). The reaction mixture was stirred overnight at ambient temperature. Brine (150 mL) was added and the mixture was made slightly basic by adding 1.0 N NaOH. The mixture was extracted once with EtOAc and twice with DCM. The combined extracts were dried over Na.sub.2SO.sub.4, filtered and concentrated to a pale yellow residue. To a solution of the crude residue, 5-chlorothiophene-2-carboxylic acid (1.26 g, 7.75 mmol) and DIEA (2.03 mL, 11.6 mmol) in DMF (25 mL) was added 50% T3P/EtOAc (7.38 mL, 12.4 mmol) and the mixture was stirred at ambient temperature for approximately two hours. The mixture was partitioned between EtOAc and saturated aqueous NaHCO.sub.3. The layers were separated and the aqueous phase was further extracted with EtOAc. The combined organic extracts were washed with water, then brine, dried over Na.sub.2SO.sub.4, filtered and concentrated. The residue was purified by flash chromatography (silica gel, 0-40% EtOAc/hexanes, gradient elution) to afford the title compound a white foam (1.60 g, 37% yield). LCMS (ESI) m/z calcd for C.sub.20H.sub.29ClN.sub.2O.sub.5S: 444.2. Found: 445.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.32 (d, J=3.8 Hz, 1H), 6.92 (d, J=3.8 Hz, 1H), 6.43 (d, J=8.2 Hz, 1H), 4.80 (dt, J=5.3, 8.4 Hz, 1H), 4.23 (q, J=7.1 Hz, 2H), 4.17-3.98 (m, 2H), 2.77-2.57 (m, 2H), 1.90-1.76 (m, 2H), 1.73-1.61 (m, 2H), 1.60-1.50 (m, 1H), 1.45 (s, 9H), 1.31 (t, J=7.1 Hz, 3H), 1.23-1.06 (m, 2H).

Step 4: Preparation of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-3-hydrazinyl-3-oxopropyl)piperidine-1-carboxylate

[0245] ##STR00090##

[0246] A solution of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-3-ethoxy-3-oxopropyl)piperidine-1-carboxylate (500 mg, 1.12 mmol) in ethanol (8.0 mL) was treated with hydrazine (0.176 mL, 5.62 mmol) and then stirred overnight at ambient temperature. LCMS indicated 50% conversion to the desired product. Additional hydrazine (0.176 mL, 5.62 mmol) was added and the mixture was stirred at ambient temperature for seven hours. LCMS indicated 90% completion. Additional hydrazine (0.176 mL, 5.62 mmol) was added and then stirred for three days. The mixture was concentrated and then placed under vacuum to afford the title compound as an off-white solid in quantitative yield. LCMS (ESI) m/z calcd for C.sub.18H.sub.27ClN.sub.4O.sub.4S: 430.1. Found: 431.3 (M+1).sup.+.

Step 5: Preparation of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-oxo-4,5-dihydro-1,3,4-oxadiazol-2-yl)ethyl)piperidine-1-carboxylate

[0247] ##STR00091##

[0248] A suspension of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-3-hydrazinyl-3-oxopropyl)piperidine-1-carboxylate (521 mg, 1.21 mmol) and DIEA (0.422 mL, 2.418 mmol) in DCM (5.0 mL) was treated with a solution of triphosgene (143 mg, 0.484 mmol) in DCM (1.0 mL, sonicated until triphosgene dissolved) to give a yellow solution. An exotherm was observed and the mixture was stirred at ambient temperature for 30 minutes. The mixture was concentrated and then purified by flash chromatography (silica gel, 0-10% MeOH/DCM, gradient elution) to afford the title compound as a colorless residue (351 mg, 37% yield). LCMS (ESI) m/z calcd for C.sub.1H.sub.25ClN.sub.4O.sub.5S: 456.1. Found: 457.2 (M+1).sup.+.

Step 6: Preparation of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-(diethylamino)-1,3,4-oxadiazol-2-yl)ethyl)piperidine-1-carboxylate

[0249] ##STR00092##

[0250] To a solution of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-oxo-4,5-dihydro-1,3,4-oxadiazol-2-yl)ethyl)piperidine-1-carboxylate (50 mg, 0.109 mmol) in DMF (1.09 mL) was sequentially added DIEA (38.2 l, 0.219 mmol) and diethylamine (22.9 l, 0.219 mmol). After stirring for several minutes, BOP (53.2 mg, 0.120 mmol) was added and the mixture was stirred at ambient temperature overnight. The mixture was purified directly by reverse phase HPLC (C18, 10-100% MeCN/water with 0.1% formic acid) to afford the title compound as a white solid (28 mg, 50% yield). LCMS (ESI) m/z calcd for C.sub.23H.sub.34ClN.sub.5O.sub.4S: 511.2. Found: 512.4 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.40 (d, J=3.9 Hz, 1H), 6.79 (d, J=3.9 Hz, 1H), 5.50-5.37 (m, 1H), 4.21-3.90 (m, 2H), 3.42 (q, J=7.0 Hz, 4H), 2.66 (m, 2H), 1.90-1.58 (m, 5H), 1.43 (s, 9H), 1.20 (t, J=7.2 Hz, 8H).

Example 45: ethyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-(diethylamino)-1,3,4-oxadiazol-2-yl)ethyl)piperidine-1-carboxylate

[0251] ##STR00093##

[0252] A solution of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-(diethylamino)-1,3,4-oxadiazol-2-yl)ethyl)piperidine-1-carboxylate (108 mg, 0.211 mmol) in methanol (1.0 mL) was treated with 4M HCl/dioxane (2.0 mL, 8.00 mmol). The mixture was stirred at ambient temperature for 30 minutes and then concentrated to a pale yellow residue. The residue was suspended in TEA (0.118 mL, 0.844 mmol) and DCM (2.0 mL) and then treated with a solution of ethyl chloroformate (0.024 mL, 0.253 mmol) in DCM (76 uL). The mixture was allowed to stir at ambient temperature for 45 minutes. The mixture was partitioned between DCM and saturated aqueous NaHCO.sub.3 and the phases were separated. The aqueous phase was extracted with DCM and the combined organic phases were dried over MgSO.sub.4, filtered and concentrated. The residue was purified by flash chromatography (silica gel, 0-100% EtOAc/hexanes, gradient elution) to afford the title compound as a white solid (73 mg, 72% yield). LCMS (ESI) m/z calcd for C.sub.21H.sub.30ClN.sub.5O.sub.4S: 483.2. Found: 484.4 (M+1).sup.+. .sup.1H NMR (400 MHz, CD.sub.3OD) 8.92 (d, J=8.6 Hz, 1H), 7.59 (d, J=3.9 Hz, 1H), 7.04 (d, J=4.3 Hz, 1H), 5.38-5.32 (m, 1H), 4.16-4.05 (m, 4H), 3.44 (q, J=7.0 Hz, 4H), 2.89-2.65 (m, 2H), 1.99-1.93 (m, 2H), 1.88-1.71 (m, 2H), 1.70-1.57 (m, 1H), 1.28-1.07 (m, 11H).

Example 46: tert-butyl 4-(3-methyl-2-(5-methylthiophene-2-carboxamido)butyl)piperidine-1-carboxylate

[0253] ##STR00094##

Step 1: Preparation of tert-butyl 4-(3-methyl-2-oxobutyl)piperidine-1-carboxylate

[0254] ##STR00095##

[0255] To a solution of tert-butyl 4-(2-(methoxy(methyl)amino)-2-oxoethyl)piperidine-1-carboxylate (1.04 g, 3.61 mmol) in THE (20 mL) at 0 C. was added 2M iPrMgCl/THF by dropwise addition. After stirring at 0 C. for 5 minutes, the solution was allowed to warm to RT. After 80 minutes, the mixture was cooled to 0 C., then treated slowly with additional 2M iPrMgCl/THF (4.52 mL, 9.04 mmol) and stirred for several minutes at ice bath temperature. The ice bath was removed and the mixture was allowed to stir at ambient temperature overnight. Saturated NH.sub.4Cl was added, the mixture was stirred for 10 minutes and then extracted with EtOAc. The extracts were washed with saturated NaHCO.sub.3, then brine, dried over Na.sub.2SO.sub.4, filtered and concentrated. The residue was purified by flash chromatography (silica gel, 0-70% EtOAc/hexanes, gradient elution) to afford the title compound as a colorless residue (0.294 g, 30% yield). .sup.1H NMR (400 MHz, CDCl.sub.3) 4.16-3.91 (m, 1H), 2.82-2.62 (m, 2H), 2.60-2.49 (m, 1H), 2.40-2.32 (m, 2H), 2.07-1.93 (m, 1H), 1.67-1.57 (m, 3H), 1.47-1.40 (m, 9H), 1.16-0.98 (m, 8H).

Step 2: Preparation of tert-butyl 4-(2-amino-3-methylbutyl)piperidine-1-carboxylate

[0256] ##STR00096##

[0257] A solution of tert-butyl 4-(3-methyl-2-oxobutyl)piperidine-1-carboxylate (294 mg, 1.091 mmol), sodium acetate (448 mg, 5.46 mmol) and hydroxylamine hydrochloride (152 mg, 2.18 mmol) in ethanol (6.0 mL) and water (3.0 mL) was stirred at 90 C. for 150 minutes. The reaction was cooled to ambient temperature, water was added and then extracted with EtOAc. The extracts were washed with brine, dried over Na.sub.2SO.sub.4, filtered and concentrated to give the crude oxime product as a viscous colorless oil. A solution of the crude oxime product in methanol (8 mL) was purged with nitrogen, treated with 10% Pd/C (40 mg, 0.376 mmol) and then stirred under hydrogen (60 psi) at 60 C. for three days. TLC indicated starting material still remained. The mixture was purged with nitrogen, additional 10% Pd/C (40 mg, 0.376 mmol) added and then stirred under hydrogen (60 psi) at 60 C. overnight. The mixture was cooled to ambient temperature, filtered through a PTFE filter and then concentrated. The residue was purified by flash chromatography (silica gel, 0-10% MeOH/DCM, MeOH containing 1% NH.sub.4OH, gradient elution) to afford the title compounds as a colorless residue (201 mg, 68%). .sup.1H NMR (400 MHz, CDCl.sub.3) 4.22-3.94 (m, 1H), 2.78-2.56 (m, 3H), 1.77-1.68 (m, 1H), 1.64-1.49 (m, 3H), 1.44 (s, 9H), 1.30-0.94 (m, 5H), 0.90-0.81 (m, 6H).

Step 3: Preparation of tert-butyl 4-(3-methyl-2-(5-methylthiophene-2-carboxamido)butyl)piperidine-1-carboxylate

[0258] ##STR00097##

[0259] A solution of tert-butyl 4-(2-amino-3-methylbutyl)piperidine-1-carboxylate (41 mg, 0.152 mmol), 5-methylthiophene-2-carboxylic acid (32.3 mg, 0.227 mmol) and DIEA (0.048 mL, 0.273 mmol) in DMF (1.0 mL) was treated with 50% T3P/EtOAc (0.144 mL, 0.243 mmol) and the mixture was allowed to stir at ambient temperature for 140 minutes. Additional 5-chlorothiophene-2-carboxylic acid (8 mg), DIEA (14 uL) and 50% T3P (45 uL) were added and the mixture was stirred at ambient temperature for 30 minutes. The mixture was purified directly by reverse phase HPLC (C18, 10-100% MeCN/water with 0.1% formic acid) to afford the title compound as a white solid (24 mg, 39% yield). LCMS (ESI) m/z calcd for C.sub.21H.sub.34N.sub.2O.sub.3S: 394.2. Found: 395.4 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.33-7.30 (m, 1H), 6.77-6.74 (m, 1H), 5.56-5.48 (m, 1H), 4.15-3.90 (m, 3H), 2.71-2.55 (m, 2H), 2.51 (s, 3H), 1.94-1.73 (m, 2H), 1.61-1.52 (m, 1H), 1.51-1.28 (m, 12H), 1.21-0.96 (m, 2H), 0.96-0.90 (m, 6H).

Example 47: tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-(pentan-3-yl)-1,2,4-oxadiazol-3-yl)ethyl)piperidine-1-carboxylate

[0260] ##STR00098##

Step 1: Preparation of 3-(1-(tert-butoxycarbonyl)piperidin-4-yl)-2-(5-chlorothiophene-2-carboxamido)propanoic acid

[0261] ##STR00099##

[0262] A solution of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-3-ethoxy-3-oxopropyl)piperidine-1-carboxylate (0.577 g, 1.30 mmol) in ethanol (3.24 ml) and THE (9.73 ml) was treated with 2M LiOH (3.24 ml, 6.48 mmol). The mixture was stirred at ambient temperature for one hour and then concentrated. Water was added and the mixture was treated with 1N HCl (3.2 mL) to give a white precipitate. The solids were collected on filter paper (Buchner funnel) under suction filtration and then dried under vacuum to give the desired product as a white solid (0.513 g, 95% yield). LCMS (ESI) m/z calcd for C.sub.18H.sub.25ClN.sub.2O.sub.5S: 416.1. Found: 417.1 (M+1).sup.+. .sup.1H NMR (400 MHz, DMSO-d.sub.6) 12.84-12.55 (m, 1H), 8.74 (d, J=8.2 Hz, 1H), 7.76 (d, J=4.3 Hz, 1H), 7.19 (d, J=3.9 Hz, 1H), 4.43-4.29 (m, 1H), 3.99-3.74 (m, 2H), 2.80-2.52 (m, 2H), 1.77-1.44 (m, 5H), 1.36 (s, 9H), 1.10-0.85 (m, 2H).

Step 2: Preparation of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyanoethyl)piperidine-1-carboxylate

[0263] ##STR00100##

[0264] A solution of 3-(1-(tert-butoxycarbonyl)piperidin-4-yl)-2-(5-chlorothiophene-2-carboxamido)propanoic acid (513 mg, 1.230 mmol) and TEA (0.515 mL, 3.69 mmol) in DCM (12 mL) at 0 C. was treated with ethyl chloroformate (0.177 mL, 1.846 mmol) and the mixture was allowed to stir at 0 C. for 45 minutes. The reaction mixture was treated with ammonia gas for 5 minutes (LCMS indicated complete conversion to the primary amide product). The mixture was concentrated to an off-white solid. To a suspension of the crude primary amide product and TEA (0.257 mL, 1.846 mmol) in THE (15 mL) at 0 C. was added TFAA (0.209 mL, 1.477 mmol) and the mixture was allowed to stir at 0 C. for 30 minutes. Additional TFAA (100 uL) was added and the mixture was allowed to stir at ambient temperature for 30 minutes. The mixture was partitioned between EtOAc and saturated NaHCO.sub.3. The aqueous layer was further extracted with EtOAc. The combined extracts were washed with brine, dried over Na.sub.2SO.sub.4, filtered and concentrated. The residue was purified by flash chromatography (silica gel, 0-50% EtOAc/hexanes, gradient elution) to afford the title compound as a viscous pale yellow oil (473 mg, 97% yield). LCMS (ESI) m/z calcd for C.sub.18H.sub.24ClN.sub.3O.sub.3S: 397.1. Found: 398.2 (M+1).sup.+. .sup.1H NMR (400 MHz, methanol-d.sub.4) 7.57 (d, J=4.3 Hz, 1H), 7.06 (d, J=3.9 Hz, 1H), 5.05 (t, J=8.0 Hz, 1H), 4.12-3.99 (m, 2H), 2.85-2.63 (m, 2H), 1.88 (t, J=7.4 Hz, 2H), 1.80-1.60 (m, 3H), 1.43 (s, 9H), 1.23-1.07 (m, 2H).

Step 3: Preparation of (Z)-tert-butyl 4-(3-amino-2-(5-chlorothiophene-2-carboxamido)-3-(hydroxyimino)propyl)piperidine-1-carboxylate

[0265] ##STR00101##

[0266] A mixture of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyanoethyl)piperidine-1-carboxylate (191 mg, 0.480 mmol), hydroxylamine hydrochloride (43.4 mg, 0.624 mmol) and sodium bicarbonate (121 mg, 1.44 mmol) in ethanol (4.0 mL) was heated to 90 C. for 3 hours and then stirred at ambient temperature overnight. Water was added and the mixture was extracted with EtOAc. The extracts were washed with brine, dried over Na.sub.2SO.sub.4, filtered and concentrated to afford the crude product as a white foam (199 mg, 96% yield). LCMS (ESI) m/z calcd for C.sub.18H.sub.27ClN.sub.4O.sub.4S: 430.1. Found: 431.3 (M+1).sup.+.

Step 4: Preparation of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-(pentan-3-yl)-1,2,4-oxadiazol-3-yl)ethyl)piperidine-1-carboxylate

[0267] ##STR00102##

[0268] A solution of tert-butyl (Z)-4-(3-amino-2-(5-chlorothiophene-2-carboxamido)-3-(hydroxyimino)propyl)piperidine-1-carboxylate (53 mg, 0.123 mmol) and TEA (0.026 mL, 0.184 mmol) in DCM (1.2 mL) at 0 C. was treated with a solution of 2-ethylbutanoyl chloride (0.020 mL, 0.15 mmol) in DCM (90 uL). The mixture was allowed to stir at ambient temperature for 10 minutes and then concentrated. The residue was suspended in acetonitrile (1.2 mL), treated with DBU (0.022 mL, 0.148 mmol) and the mixture was transferred to a microwave vial. The mixture was subjected to microwave heating at 120 C. for 60 minutes. LCMS indicated approximately 65% conversion to the desired product. The reaction mixture was irradiated in the microwave at 120 C. for an additional 60 minutes. The mixture was concentrated and then purified by flash chromatography (silica gel, 0-50% EtOAc/hexanes, gradient elution) to afford the title compound as a colorless residue (32 mg, 50%). LCMS (ESI) m/z calcd for C.sub.24H.sub.35ClN.sub.4O.sub.4S: 510.2. Found: 511.3 (M+1).sup.+. .sup.1H NMR (400 MHz, CD.sub.3OD) 7.62 (d, J=4.3 Hz, 1H), 7.03 (d, J=4.3 Hz, 1H), 5.40-5.34 (m, 1H), 4.10-4.01 (m, 2H), 2.95-2.86 (m, 1H), 2.82-2.59 (m, 2H), 2.01-1.86 (m, 2H), 1.86-1.68 (m, 6H), 1.65-1.53 (m, 1H), 1.43 (s, 9H), 0.89-0.81 (m, 6H).

Example 48: tert-butyl 4-(2-(5-(diethylamino)-1,3,4-oxadiazol-2-yl)-2-(5-methylthiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0269] ##STR00103##

[0270] The title compound was prepared according to the method described herein for the synthesis of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-(diethylamino)-1,3,4-oxadiazol-2-yl)ethyl)piperidine-1-carboxylate employing 5-methylthiophene-2-carboxylic acid in step 3. The product was isolated as a pale yellow solid after flash chromatography (silica gel, 0-100% EtOAc/hexanes, gradient elution). LCMS (ESI) m/z calcd for C.sub.24H.sub.37N.sub.5O.sub.4S: 491.3. Found: 492.5 (M+1).sup.+. .sup.1H NMR (400 MHz, methanol-d.sub.4) 7.56 (d, J=3.5 Hz, 1H), 6.83-6.80 (m, 1H), 5.40-5.32 (m, 1H), 4.05 (d, J=12.9 Hz, 2H), 3.43 (q, J=7.0 Hz, 4H), 2.81-2.61 (m, 2H), 2.51 (s, 3H), 2.01-1.90 (m, 2H), 1.84-1.81 (m, 1H), 1.75-1.69 (m, 1H), 1.68-1.56 (m, 1H), 1.43 (s, 9H), 1.27-1.05 (m, 8H).

Example 49: tert-butyl 4-(2-(5-ethylthiophene-2-carboxamido)-3-methylbutyl)piperidine-1-carboxylate

[0271] ##STR00104##

[0272] The title compound was prepared according to the method described herein for the synthesis of tert-butyl 4-(3-methyl-2-(5-methylthiophene-2-carboxamido)butyl)piperidine-1-carboxylate, employing 5-ethylthiophene-2-carboxylic acid in step 3. The product was isolated as a white solid after reverse phase HPLC (C18, 10-100% MeCN/water with 0.1% formic acid) purification. LCMS (ESI) m/z calcd for C.sub.22H.sub.36N.sub.2O.sub.3S: 408.2. Found: 409.4 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.33 (d, J=3.5 Hz, 1H), 6.77 (d, J=3.9 Hz, 1H), 5.53 (d, J=9.8 Hz, 1H), 4.17-3.87 (m, 3H), 2.86 (q, J=7.5 Hz, 2H), 2.71-2.56 (m, 2H), 1.93-1.85 (m, 1H), 1.83-1.73 (m, 1H), 1.62-1.52 (m, 1H), 1.51-1.27 (m, 15H), 1.21-0.87 (m, 8H).

Example 50: tert-butyl 4-(2-(5-(cyclopropyl(ethyl)amino)-1,3,4-oxadiazol-2-yl)-2-(5-methylthiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0273] ##STR00105##

[0274] The title compound was prepared according to the method described herein for the synthesis of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-(diethylamino)-1,3,4-oxadiazol-2-yl)ethyl)piperidine-1-carboxylate, employing 5-methylthiophene-2-carboxylic acid in step 3 and N-ethylcyclopropanamine in step 6. The product was isolated as a colorless residue after reverse phase HPLC (C18, 10-100% MeCN/water with 0.1% formic acid) purification. LCMS (ESI) m/z calcd for C.sub.25H.sub.37N.sub.5O.sub.4S: 503.3. Found: 504.4 (M+1).sup.+. .sup.1H NMR (400 MHz, methanol-d.sub.4) 7.56 (d, J=3.9 Hz, 1H), 6.85-6.78 (m, 1H), 5.39-5.33 (m, 1H), 4.10-4.01 (m, 2H), 3.46 (q, J=7.2 Hz, 2H), 2.85-2.60 (m, 3H), 2.50 (s, 3H), 2.04-1.89 (m, 2H), 1.86-1.78 (m, 1H), 1.77-1.70 (m, 1H), 1.68-1.57 (m, 1H), 1.43 (s, 9H), 1.26-1.05 (m, 5H), 0.87-0.78 (m, 2H), 0.74-0.65 (m, 2H).

Example 51: phenyl 4-(2-(5-methylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0275] ##STR00106##

Step 1: Preparation of tert-butyl 4-(2-(5-methylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0276] ##STR00107##

[0277] A solution of tert-butyl 4-(2-amino-2-phenylethyl)piperidine-1-carboxylate (798 mg, 2.62 mmol), 5-methylthiophene-2-carboxylic acid (373 mg, 2.62 mmol) and DIEA (0.687 mL, 3.93 mmol) in DMF (15 mL) was treated with 50% T3P/EtOAc (2.497 mL, 4.19 mmol) and the mixture was stirred at ambient temperature overnight. Saturated NaHCO.sub.3 was added and the mixture was extracted with EtOAc. The extracts were washed with water, then brine, dried over Na.sub.2SO.sub.4, filtered and concentrated. The residue was purified by flash chromatography (silica gel, 0-50% EtOAc/hexanes, gradient elution) to afford the title compound a white foam (350 mg, 31% yield). LCMS (ESI) m/z calcd for C.sub.24H.sub.32N.sub.2O.sub.3S: 428.2. Found: 429.4 (M+1).sup.+. .sup.1H NMR (400 MHz, methanol-d.sub.4) 8.57 (d, J=8.6 Hz, 1H), 7.56 (d, J=3.5 Hz, 1H), 7.39-7.27 (m, 4H), 7.25-7.18 (m, 1H), 6.80 (d, J=3.1 Hz, 1H), 5.22-5.13 (m, 1H), 4.04 (d, J=13.3 Hz, 2H), 2.78-2.59 (m, 2H), 2.49 (s, 3H), 1.96-1.86 (m, 1H), 1.85-1.78 (m, 1H), 1.77-1.65 (m, 2H), 1.59-1.48 (m, 1H), 1.43 (s, 9H), 1.22-1.05 (m, 2H).

Step 2: Preparation of phenyl 4-(2-(5-methylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0278] ##STR00108##

[0279] A solution of tert-butyl 4-(2-(5-methylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate (70 mg, 0.163 mmol) in methanol (0.75 mL) was treated with 4M HCl/dioxane (1.50 mL, 6.00 mmol). The mixture was stirred for 20 minutes at ambient temperature and then concentrated to give the intermediate amine hydrochloride as a pale yellow residue (78 mg). To a suspension of the intermediate and TEA (0.091 mL, 0.653 mmol) in DCM (3.0 mL) at 0 C. was added a solution of phenyl chloroformate (0.025 mL, 0.20 mmol) in DCM (450 uL) and the mixture stirred at ambient temperature for 20 minutes. Saturated NaHCO.sub.3 was added and the mixture was extracted with DCM. The combined organic phases were dried over MgSO.sub.4, filtered and concentrated. The residue was purified by flash chromatography (silica gel, 0-50% EtOAc/hexanes, gradient elution) to afford the title compound as a white solid (54 mg, 73%). LCMS (ESI) m/z calcd for C.sub.26H.sub.28N.sub.2O.sub.3S: 448.2. Found: 449.3 (M+1).sup.+. .sup.1H NMR (400 MHz, methanol-d.sub.4) 8.60 (d, J=8.6 Hz, 1H), 7.58 (d, J=3.9 Hz, 1H), 7.42-7.29 (m, 6H), 7.26-7.17 (m, 2H), 7.08-7.04 (m, 2H), 6.82-6.79 (m, 1H), 5.27-5.16 (m, 1H), 4.35-4.22 (m, 1H), 4.19-4.08 (m, 1H), 3.06-2.74 (m, 2H), 2.49 (s, 3H), 2.02-1.55 (m, 5H), 1.41-1.18 (m, 2H).

Example 52: tert-butyl 4-(2-(5-(ethyl(methyl)amino)-1,3,4-oxadiazol-2-yl)-2-(5-methylthiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0280] ##STR00109##

[0281] The title compound was prepared according to the method described herein for the synthesis of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-(diethylamino)-1,3,4-oxadiazol-2-yl)ethyl)piperidine-1-carboxylate, employing 5-methylthiophene-2-carboxylic acid in step 3 and N-methylethanamine in step 6. The product was isolated as a colorless residue after flash chromatography (silica gel, 0-100% EtOAc/hexanes, gradient elution). LCMS (ESI) m/z calcd for C.sub.23H.sub.35N.sub.5O.sub.4S: 477.2. Found: 478.4 (M+1).sup.+. .sup.1H NMR (400 MHz, methanol-d.sub.4) 7.56 (d, J=3.9 Hz, 1H), 6.85-6.79 (m, 1H), 5.39-5.33 (m, 1H), 4.10-4.00 (m, 2H), 3.43 (q, J=7.0 Hz, 2H), 3.05-3.01 (m, 3H), 2.82-2.59 (m, 2H), 2.51 (s, 3H), 2.02-1.89 (m, 2H), 1.86-1.78 (m, 1H), 1.76-1.69 (m, 1H), 1.68-1.55 (m, 1H), 1.49-1.37 (m, 9H), 1.26-1.05 (m, 5H).

Example 53: phenyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-(diethylamino)-1,3,4-oxadiazol-2-yl)ethyl)piperidine-1-carboxylate

[0282] ##STR00110##

[0283] A solution of tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-(diethylamino)-1,3,4-oxadiazol-2-yl)ethyl)piperidine-1-carboxylate (60 mg, 0.117 mmol) in methanol (0.5 mL) was treated with 4N HCl/dioxane (1.00 mL, 4.00 mmol) at ambient temperature. The mixture was stirred at ambient temperature for 10 minutes and then concentrated to afford the amine hydrochloride intermediate as a pale yellow residue. An ice cold suspension of the intermediate and TEA (0.065 mL, 0.469 mmol) in DCM (2.0 mL) was treated with a solution of phenyl chloroformate (0.018 mL, 0.141 mmol) in DCM (0.31 mL). The cooling bath was removed and the mixture was stirred at ambient temperature for 45 minutes. The mixture was partitioned between DCM and saturated NaHCO.sub.3 and the phases were separated. The aqueous phase was extracted with DCM and the combined organic phases were dried over MgSO4, filtered and concentrated. The residue was purified by reverse phase HPLC (C18, 10-100% MeCN/water with 0.1% formic acid) followed by flash chromatography (silica gel, 30-100% EtOAc/hexanes, gradient elution) to afford the title compound as a colorless residue (12 mg, 18% yield). LCMS (ESI) m/z calcd for C.sub.25H.sub.30ClN.sub.5O.sub.4S: 531.2. Found: 532.4 (M+1).sup.+. .sup.1H NMR (400 MHz, CDCl.sub.3) 7.78-7.47 (m, 1H), 7.42-7.30 (m, 3H), 7.22-7.14 (m, 1H), 7.11-7.06 (m, 2H), 6.84 (d, J=3.9 Hz, 1H), 5.51-5.43 (m, 1H), 4.34-4.18 (m, 2H), 3.43 (q, J=7.0 Hz, 4H), 3.08-2.63 (m, 2H), 2.00-1.84 (m, 3H), 1.81-1.69 (m, 2H), 1.31-1.16 (m, 8H).

[0284] Examples 54-245 were prepared using methods similar to those described herein for examples 1-53.

Example 54: tert-butyl 4-(2-(4-fluorobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0285] ##STR00111##

Example 55: isopropyl 4-(2-(4-fluorobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0286] ##STR00112##

Example 56: isobutyl 4-(2-(4-fluorobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0287] ##STR00113##

Example 57: tert-butyl 4-(2-(4-bromobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0288] ##STR00114##

Example 58: tert-butyl 4-(2-(5-fluorothiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0289] ##STR00115##

Example 59: tert-butyl 4-(2-cyclopentyl-2-(5-methylthiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0290] ##STR00116##

Example 60: tert-butyl 4-(2-(5-ethylthiophene-2-carboxamido)-4-methylpentyl)piperidine-1-carboxylate

[0291] ##STR00117##

Example 61: cyclobutyl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0292] ##STR00118##

Example 62: prop-2-yn-1-yl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0293] ##STR00119##

Example 63: (S)-tert-butyl 4-(2-(4-bromobenzamido)-2-cyclopropylethyl)piperidine-1-carboxylate

[0294] ##STR00120##

Example 64: tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclohexylethyl)piperidine-1-carboxylate

[0295] ##STR00121##

Example 65: (S)-tert-butyl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0296] ##STR00122##

Example 66: (S)-ethyl 4-(2-(5-ethylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0297] ##STR00123##

Example 67: phenyl 4-(2-(4-chlorobenzamido)-4-methylpentyl)piperidine-1-carboxylate

[0298] ##STR00124##

Example 68: tert-butyl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0299] ##STR00125##

Example 69: tert-butyl 4-(2-(5-methylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0300] ##STR00126##

Example 70: (R)-tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0301] ##STR00127##

Example 71: tert-butyl 4-(2-(4-bromo-3-fluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0302] ##STR00128##

Example 72: tert-butyl 4-(2-(4-iodobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0303] ##STR00129##

Example 73: tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-(dimethylamino)-1,3,4-oxadiazol-2-yl)ethyl)piperidine-1-carboxylate

[0304] ##STR00130##

Example 74: tert-butyl 4-(2-(4-bromobenzamido)-3-methylbutyl)piperidine-1-carboxylate

[0305] ##STR00131##

Example 75: tert-butyl 4-(2-(4-chlorobenzamido)-4-methylpentyl)piperidine-1-carboxylate

[0306] ##STR00132##

Example 76: tert-butyl 4-(2-(4-fluorobenzamido)-4-methylpentyl)piperidine-1-carboxylate

[0307] ##STR00133##

Example 77: cyclopropyl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0308] ##STR00134##

Example 78: tert-butyl 4-(2-cyclopentyl-2-(5-ethylthiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0309] ##STR00135##

Example 79: tert-butyl 4-(2-(5-fluorothiophene-2-carboxamido)-4-methylpentyl)piperidine-1-carboxylate

[0310] ##STR00136##

Example 80: tert-butyl 4-(2-cyclohexyl-2-(5-methylthiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0311] ##STR00137##

Example 81: (S)-ethyl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0312] ##STR00138##

Example 82: tert-butyl 4-(2-(5-(ethyl(2-methoxyethyl)amino)-1,3,4-oxadiazol-2-yl)-2-(5-methylthiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0313] ##STR00139##

Example 83: (S)-tert-butyl 4-(4-(benzylamino)-2-(5-chlorothiophene-2-carboxamido)butyl)piperidine-1-carboxylate

[0314] ##STR00140##

Example 84: tert-butyl 4-(2-(4-chloro-3-fluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0315] ##STR00141##

Example 85: ethyl 4-(2-(4-fluorobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0316] ##STR00142##

Example 86: tert-butyl 4-(2-phenyl-2-(4-(prop-2-yn-1-yloxy)benzamido)ethyl)piperidine-1-carboxylate

[0317] ##STR00143##

Example 87: tert-butyl 4-(2-phenyl-2-(5-propylthiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0318] ##STR00144##

Example 88: tert-butyl 4-(2-(4-chlorobenzamido)-3-methylbutyl)piperidine-1-carboxylate

[0319] ##STR00145##

Example 89: propyl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0320] ##STR00146##

Example 90: (S)-tert-butyl 4-(2-(4-chlorobenzamido)-2-cyclopropylethyl)piperidine-1-carboxylate

[0321] ##STR00147##

Example 91: tert-butyl 4-(2-(4-bromobenzamido)-2-cyclohexylethyl)piperidine-1-carboxylate

[0322] ##STR00148##

Example 92: tert-butyl 4-(2-cyclohexyl-2-(5-fluorothiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0323] ##STR00149##

Example 93: N-(2-(1-(2,2-difluoro-2-phenylacetyl)piperidin-4-yl)-1-phenylethyl)-5-methylthiophene-2-carboxamide

[0324] ##STR00150##

Example 94: 5-methyl-N-(1-phenyl-2-(1-(2,2,2-trifluoroacetyl)piperidin-4-yl)ethyl)thiophene-2-carboxamide

[0325] ##STR00151##

Example 95: N-(2-(1-(2,2-difluorobutanoyl)piperidin-4-yl)-1-phenylethyl)-5-methylthiophene-2-carboxamide

[0326] ##STR00152##

Example 96: tert-butyl 4-(2-(5-(butyl(ethyl)amino)-1,3,4-oxadiazol-2-yl)-2-(5-methylthiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0327] ##STR00153##

Example 97: tert-butyl 4-(2-(4-cyclopropylbenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0328] ##STR00154##

Example 98: tert-butyl 4-(2-(5-cyclopropylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0329] ##STR00155##

Example 99: tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-3-methylbutyl)piperidine-1-carboxylate

[0330] ##STR00156##

Example 100: cyclopentyl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0331] ##STR00157##

Example 101: tert-butyl 4-(2-(3-fluoro-4-iodobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0332] ##STR00158##

Example 102: ethyl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0333] ##STR00159##

Example 103: isopropyl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0334] ##STR00160##

Example 104: phenyl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0335] ##STR00161##

Example 105: cyclopropylmethyl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0336] ##STR00162##

Example 106: tert-butyl 4-(2-cyclohexyl-2-(5-ethylthiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0337] ##STR00163##

Example 107: tert-butyl 4-(2-(4-fluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0338] ##STR00164##

Example 108: ethyl 4-(2-cyclopropyl-2-(4-fluorobenzamido)ethyl)piperidine-1-carboxylate

[0339] ##STR00165##

Example 109: tert-butyl 4-(2-(3-fluoro-4-methoxybenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0340] ##STR00166##

Example 110: tert-butyl 4-(2-phenyl-2-(4-(trifluoromethyl)benzamido)ethyl)piperidine-1-carboxylate

[0341] ##STR00167##

Example 111: tert-butyl 4-(2-(6-methoxypyridin-3-yl)-2-(4-(methylthio)benzamido)ethyl)piperidine-1-carboxylate

[0342] ##STR00168##

Example 112: tert-butyl 4-(2-(5-(diethylamino)-1,3,4-oxadiazol-2-yl)-2-(4-fluorobenzamido)ethyl)piperidine-1-carboxylate

[0343] ##STR00169##

Example 113: tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-((2-methoxyethyl)(methyl)amino)-1,3,4-oxadiazol-2-yl)ethyl)piperidine-1-carboxylate

[0344] ##STR00170##

Example 114: tert-butyl 4-(2-(3-fluoro-4-(prop-2-yn-1-yloxy)benzamido)-2-phenylethyl)piperidine-1-carboxylate

[0345] ##STR00171##

Example 115: tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopentylethyl)piperidine-1-carboxylate

[0346] ##STR00172##

Example 116: tert-butyl 4-(2-cyclopentyl-2-(5-fluorothiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0347] ##STR00173##

Example 117: benzyl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0348] ##STR00174##

Example 118: tert-butyl 4-(2-(4-ethylbenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0349] ##STR00175##

Example 119: tert-butyl 4-(2-phenyl-2-(4-vinylbenzamido)ethyl)piperidine-1-carboxylate

[0350] ##STR00176##

Example 120: ethyl 4-(2-(4-fluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0351] ##STR00177##

Example 121: phenyl 4-(2-(4-fluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0352] ##STR00178##

Example 122: tert-butyl 4-(2-(6-(diethylamino)pyridin-3-yl)-2-(4-fluorobenzamido)ethyl)piperidine-1-carboxylate

[0353] ##STR00179##

Example 123: (S)-tert-butyl 4-(2-(6-methoxynicotinamido)-2-phenylethyl)piperidine-1-carboxylate

[0354] ##STR00180##

Example 124: tert-butyl 4-(2-(5-isopropylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0355] ##STR00181##

Example 125: isobutyl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0356] ##STR00182##

Example 126: tert-butyl 4-(2-(4-bromobenzamido)-2-cyclopentylethyl)piperidine-1-carboxylate

[0357] ##STR00183##

Example 127: tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-(ethylamino)-1,3,4-oxadiazol-2-yl)ethyl)piperidine-1-carboxylate

[0358] ##STR00184##

Example 128: tert-butyl 4-(2-(5-chlorothiophene-3-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0359] ##STR00185##

Example 129: (S)-tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-4-morpholinobutyl)piperidine-1-carboxylate

[0360] ##STR00186##

Example 130: tert-butyl 4-(2-(4-methylbenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0361] ##STR00187##

Example 131: tert-butyl 4-(2-phenyl-2-(thiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0362] ##STR00188##

Example 132: tert-butyl 4-(2-(6-(cyclohexyloxy)pyridin-3-yl)-2-(4-fluorobenzamido)ethyl)piperidine-1-carboxylate

[0363] ##STR00189##

Example 133: tert-butyl 4-(2-(4-cyclopropyl-3-fluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0364] ##STR00190##

Example 134: methyl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0365] ##STR00191##

Example 135: tert-butyl 4-(2-(4-chlorobenzamido)-2-cyclohexylethyl)piperidine-1-carboxylate

[0366] ##STR00192##

Example 136: N-(2-(1-(2,2-difluoro-2-(pyridin-2-yl)acetyl)piperidin-4-yl)-1-phenylethyl)-5-methylthiophene-2-carboxamide

[0367] ##STR00193##

Example 137: 5-methyl-N-(1-phenyl-2-(1-phenylpiperidin-4-yl)ethyl)thiophene-2-carboxamide

[0368] ##STR00194##

Example 138: tert-butyl 4-(2-benzamido-2-phenylethyl)piperidine-1-carboxylate

[0369] ##STR00195##

Example 139: tert-butyl 4-(2-(3-fluoro-4-methylbenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0370] ##STR00196##

Example 140: tert-butyl 4-(2-(5-(benzyl(methyl)amino)-1,3,4-oxadiazol-2-yl)-2-(5-chlorothiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0371] ##STR00197##

Example 141: tert-butyl 4-(2-(4-cyanobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0372] ##STR00198##

Example 142: tert-butyl 4-(3-(benzylamino)-2-(4-fluorobenzamido)propyl)piperidine-1-carboxylate

[0373] ##STR00199##

Example 143: tert-butyl 4-(2-(4-methoxybenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0374] ##STR00200##

Example 144: tert-butyl 4-(2-(4-fluorobenzamido)-2-(6-isopropoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0375] ##STR00201##

Example 145: methyl 4-(2-(4-fluorobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0376] ##STR00202##

Example 146: tert-butyl 4-(2-(3-fluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0377] ##STR00203##

Example 147: tert-butyl 4-(2-(3,4-difluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0378] ##STR00204##

Example 148: (S)-tert-butyl 4-(2-((6-chlorobenzo[d]oxazol-2-yl)amino)-2-cyclopropylethyl)piperidine-1-carboxylate

[0379] ##STR00205##

Example 149: tert-butyl 4-(2-(4-(but-2-yn-1-yloxy)benzamido)-2-phenylethyl)piperidine-1-carboxylate

[0380] ##STR00206##

Example 150: cyclohexyl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0381] ##STR00207##

Example 151: tert-butyl 4-(2-(4-chlorobenzamido)-2-cyclopentylethyl)piperidine-1-carboxylate

[0382] ##STR00208##

Example 152: tert-butyl 4-(2-cyclohexyl-2-(4-fluorobenzamido)ethyl)piperidine-1-carboxylate

[0383] ##STR00209##

Example 153: tert-butyl 4-(2-(5-methylthiophene-3-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0384] ##STR00210##

Example 154: N-(2-(1-butyrylpiperidin-4-yl)-1-phenylethyl)-4-chlorobenzamide

[0385] ##STR00211##

Example 155: (S)-tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)pent-4-en-1-yl)piperidine-1-carboxylate

[0386] ##STR00212##

Example 156: N-(2-(1-benzoylpiperidin-4-yl)-1-phenylethyl)-5-methylthiophene-2-carboxamide

[0387] ##STR00213##

Example 157: tert-butyl 4-(2-(6-methoxynicotinamido)-2-phenylethyl)piperidine-1-carboxylate

[0388] ##STR00214##

Example 158: ethyl 4-(2-cyclopropyl-2-(6-methoxynicotinamido)ethyl)piperidine-1-carboxylate

[0389] ##STR00215##

Example 159: tert-butyl 4-(2-phenyl-2-(thiophene-3-carboxamido)ethyl)piperidine-1-carboxylate

[0390] ##STR00216##

Example 160: tert-butyl 4-(2-(6-(benzyloxy)pyridin-3-yl)-2-(4-fluorobenzamido)ethyl)piperidine-1-carboxylate

[0391] ##STR00217##

Example 161: tert-butyl 4-(2-(4-chloro-3-methoxybenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0392] ##STR00218##

Example 162: tert-butyl 4-(2-(4-cyano-3-fluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0393] ##STR00219##

Example 163:4-chloro-N-(2-(1-(3-methylbutanoyl)piperidin-4-yl)-1-phenylethyl)benzamide

[0394] ##STR00220##

Example 164: 4-chloro-N-(2-(1-(3,3-dimethylbutanoyl)piperidin-4-yl)-1-phenylethyl)benzamide

[0395] ##STR00221##

Example 165: N-(tert-butyl)-4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxamide

[0396] ##STR00222##

Example 166: 4-chloro-N-(2-(1-(isobutylsulfonyl)piperidin-4-yl)-1-phenylethyl)benzamide

[0397] ##STR00223##

Example 167: tert-butyl 4-(2-(4-(but-2-yn-1-yloxy)-3-fluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0398] ##STR00224##

Example 168: tert-butyl 4-(2-(4-chlorothiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0399] ##STR00225##

Example 169: tert-butyl 4-(2-(4-fluorobenzamido)-2-(5-(pentan-3-yl)-1,2,4-oxadiazol-3-yl)ethyl)piperidine-1-carboxylate

[0400] ##STR00226##

Example 170: (S)-tert-butyl 4-(2-cyclopropyl-2-((5-phenyloxazol-2-yl)amino)ethyl)piperidine-1-carboxylate

[0401] ##STR00227##

Example 171: tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-(propylamino)-1,3,4-oxadiazol-2-yl)ethyl)piperidine-1-carboxylate

[0402] ##STR00228##

Example 172: 5-methyl-N-(1-phenyl-2-(1-(3,3,3-trifluoropropanoyl)piperidin-4-yl)ethyl)thiophene-2-carboxamide

[0403] ##STR00229##

Example 173: methyl 4-(2-(4-fluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0404] ##STR00230##

Example 174: tert-butyl 4-(2-(4-fluorobenzamido)-2-(6-methylpyridin-3-yl)ethyl)piperidine-1-carboxylate

[0405] ##STR00231##

Example 175: tert-butyl 4-(2-(benzo[d][1,3]dioxole-5-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0406] ##STR00232##

Example 176: tert-butyl 4-(2-(1-benzyl-6-oxo-1,6-dihydropyridin-3-yl)-2-(4-fluorobenzamido)ethyl)piperidine-1-carboxylate

[0407] ##STR00233##

Example 177: (R)-ethyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropylethyl)piperdine-1-carboxylate

[0408] ##STR00234##

Example 178: tert-butyl 4-(2-(4-(methylthio)benzamido)-2-phenylethyl)piperidine-1-carboxylate

[0409] ##STR00235##

Example 179: tert-butyl 4-(2-(4-methylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0410] ##STR00236##

Example 180: tert-butyl 4-(2-phenyl-2-(5-vinylthiophene-2-carboxamido)ethyl)piperidine-1-carboxylate

[0411] ##STR00237##

Example 181: tert-butyl 4-(2-(1H-indole-7-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0412] ##STR00238##

Example 182: tert-butyl 4-(2-(benzo[b]thiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0413] ##STR00239##

Example 183: (R)-tert-butyl 4-(2-(4-fluorobenzamido)-2-(6-methoxypyridin-3-yl)ethyl)piperidine-1-carboxylate

[0414] ##STR00240##

Example 184: 4-(2-(4-chlorobenzamido)-2-phenylethyl)-N-isopropylpiperidine-1-carboxamide

[0415] ##STR00241##

Example 185: oxetan-3-yl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0416] ##STR00242##

Example 186: tetrahydro-2H-pyran-4-yl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0417] ##STR00243##

Example 187: neopentyl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0418] ##STR00244##

Example 188: (R)-isopropyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropylethyl)piperidine-1-carboxylate

[0419] ##STR00245##

Example 189: tert-butyl 4-(2-(6-cyanonicotinamido)-2-phenylethyl)piperidine-1-carboxylate

[0420] ##STR00246##

Example 190: tert-butyl 4-(2-(cyclohexanecarboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0421] ##STR00247##

Example 191: tert-butyl 4-(2-(2-methylthiazole-5-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0422] ##STR00248##

Example 192: tert-butyl 4-(2-phenyl-2-(4-propoxybenzamido)ethyl)piperidine-1-carboxylate

[0423] ##STR00249##

Example 193: 4-chloro-N-(2-(1-(cyclopentylsulfonyl)piperidin-4-yl)-1-phenylethyl)benzamide

[0424] ##STR00250##

Example 194: tert-butyl 4-(2-(2-hydroxybenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0425] ##STR00251##

Example 195: tert-butyl 4-(2-(4-hydroxybenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0426] ##STR00252##

Example 196: tert-butyl 4-(2-(3-fluoro-4-hydroxybenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0427] ##STR00253##

Example 197:4-chloro-N-(1-phenyl-2-(1-(piperidin-1-ylsulfonyl)piperidin-4-yl)ethyl)benzamide

[0428] ##STR00254##

Example 198: tert-butyl 4-(2-(3-cyclopentyl-1,2,4-oxadiazol-5-yl)-2-(4-fluorobenzamido)ethyl)piperidine-1-carboxylate

[0429] ##STR00255##

Example 199: tert-butyl 4-(2-(3-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0430] ##STR00256##

Example 200: tert-butyl 4-(2-(3-(4-fluorophenyl)ureido)-2-phenylethyl)piperidine-1-carboxylate

[0431] ##STR00257##

Example 201: tert-butyl 4-(2-(bicyclo[2.2.2]octane-1-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0432] ##STR00258##

Example 202: tert-butyl 4-(2-(4-fluorobenzamido)-2-(6-(2-methoxyethoxy)pyridin-3-yl)ethyl)piperidine-1-carboxylate

[0433] ##STR00259##

Example 203: tert-butyl 4-(2-(3-chloro-4-fluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0434] ##STR00260##

Example 204: tert-butyl 4-(2-(5-methylfuran-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0435] ##STR00261##

Example 205: tert-butyl 4-(2-(3,4-dichlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0436] ##STR00262##

Example 206: (R)-methyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropylethyl)piperidine-1-carboxylate

[0437] ##STR00263##

Example 207: tert-butyl 4-(2-(4-fluorobenzamido)-2-(pyridin-3-yl)ethyl)piperidine-1-carboxylate

[0438] ##STR00264##

Example 208: tert-butyl 4-(2-(4-fluorobenzamido)-2-(pyridin-4-yl)ethyl)piperidine-1-carboxylate

[0439] ##STR00265##

Example 209: tert-butyl 4-(2-(cycloheptanecarboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0440] ##STR00266##

Example 210: tert-butyl 4-(2-(3,3-dimethylbutanamido)-2-phenylethyl)piperidine-1-carboxylate

[0441] ##STR00267##

Example 211: tert-butyl 4-(2-(2,5-difluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0442] ##STR00268##

Example 212: tert-butyl 4-(2-(4-isopropylbenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0443] ##STR00269##

Example 213: tert-butyl 4-(2-(4-fluoro-3-methylbenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0444] ##STR00270##

Example 214: (R)-tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-cyclopropylethyl)piperidine-1-carboxylate

[0445] ##STR00271##

Example 215: 4-chloro-N-(1-phenyl-2-(1-(phenylsulfonyl)piperidin-4-yl)ethyl)benzamide

[0446] ##STR00272##

Example 216: tert-butyl 4-(2-(3-methoxybenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0447] ##STR00273##

Example 217: tert-butyl 4-(2-(6-methylnicotinamido)-2-phenylethyl)piperidine-1-carboxylate

[0448] ##STR00274##

Example 218: tert-butyl 4-(2-(2-fluoro-4-methylbenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0449] ##STR00275##

Example 219: tert-butyl 4-(2-(2-fluorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0450] ##STR00276##

Example 220: tert-butyl 4-(2-phenyl-2-(1H-pyrrole-2-carboxamido)ethyl)piperidine-1-carboxylate

[0451] ##STR00277##

Example 221: tert-butyl 4-(2-(5-cyclopropyl-1,3,4-oxadiazol-2-yl)-2-(4-fluorobenzamido)ethyl)piperidine-1-carboxylate

[0452] ##STR00278##

Example 222: N-(2-(1-acetylpiperidin-4-yl)-1-phenylethyl)-4-chlorobenzamide

[0453] ##STR00279##

Example 223: tert-butyl 4-(2-(4-fluorobenzamido)-2-(5-isopropyl-1,3,4-oxadiazol-2-yl)ethyl)piperidine-1-carboxylate

[0454] ##STR00280##

Example 224: tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-2-(5-oxo-4,5-dihydro-1,3,4-oxadiazol-2-yl)ethyl)piperidine-1-carboxylate

[0455] ##STR00281##

Example 225: tert-butyl 4-(2-(4-fluorobenzamido)-3-(isobutylamino)propyl)piperidine-1-carboxylate

[0456] ##STR00282##

Example 226: tert-butyl 4-(2-(4-fluorobenzamido)-2-(pyridin-2-yl)ethyl)piperidine-1-carboxylate

[0457] ##STR00283##

Example 227: tert-butyl 4-(2-(5-isobutylthiophene-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0458] ##STR00284##

Example 228: tert-butyl 4-(2-(furan-2-carboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0459] ##STR00285##

Example 229: (S)-tert-butyl 4-(2-((2-chloropyrimidin-4-yl)amino)-2-cyclopropylethyl)piperidine-1-carboxylate

[0460] ##STR00286##

Example 230: 4-chloro-N-(1-phenyl-2-(1-(piperidine-1-carbonyl)piperidin-4-yl)ethyl)benzamide

[0461] ##STR00287##

Example 231: (S)-tert-butyl 4-(2-(5-chlorothiophene-2-carboxamido)-4-(ethylamino)butyl)piperidine-1-carboxylate

[0462] ##STR00288##

Example 232: tert-butyl 4-(2-(cyclopentanecarboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0463] ##STR00289##

Example 233: tert-butyl 4-(2-(4-methylcyclohexanecarboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0464] ##STR00290##

Example 234: (R)-tert-butyl 4-(2-(4-chlorobenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0465] ##STR00291##

Example 235: tert-butyl 4-(2-(4-fluorobenzamido)-3-((2-methoxyethyl)amino)propyl)piperidine-1-carboxylate

[0466] ##STR00292##

Example 236: tert-butyl 4-(2-(nicotinamido)-2-phenylethyl)piperidine-1-carboxylate

[0467] ##STR00293##

Example 237: 4-fluoro-N-(2-(1-(3-methoxypropanoyl)piperidin-4-yl)-1-phenylethyl)benzamide

[0468] ##STR00294##

Example 238: 4-fluoro-N-(2-(1-(3-methoxybutanoyl)piperidin-4-yl)-1-phenylethyl)benzamide

[0469] ##STR00295##

Example 239: tert-butyl 4-(2-(4-fluorobenzamido)-2-(5-methyloxazol-2-yl)ethyl)piperidine-1-carboxylate

[0470] ##STR00296##

Example 240: tert-butyl 4-(2-(1-methylcyclohexanecarboxamido)-2-phenylethyl)piperidine-1-carboxylate

[0471] ##STR00297##

Example 241: tert-butyl 4-(2-(4-isopropoxybenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0472] ##STR00298##

Example 242: tert-butyl 4-(2-(4-isobutylbenzamido)-2-phenylethyl)piperidine-1-carboxylate

[0473] ##STR00299##

Example 243: 4-chloro-N-(2-(1-(morpholine-4-carbonyl)piperidin-4-yl)-1-phenylethyl)benzamide

[0474] ##STR00300##

Example 244: 2-((5-(2-(1-(tert-butoxycarbonyl)piperidin-4-yl)-1-(5-chlorothiophene-2-carboxamido)ethyl)-1,3,4-oxadiazol-2-yl)(methyl)amino)acetic acid

[0475] ##STR00301##

Example 245: (S)-tert-butyl 4-(2-((5-chloropyridin-2-yl)amino)-2-cyclopropylethyl)piperidine-1-carboxylate

[0476] ##STR00302##

PBMC IDO1 Assay:

[0477] Data shown in Table 1. Compounds of the present invention were tested via high-throughput cellular assays utilizing detection of kynurenine via mass spectrometry and cytotoxicity as end-points. For the mass spectrometry and cytotoxicity assays, human peripheral blood mononuclear cells (PBMC) (PB003F; AIICells, Alameda, Calif.) were stimulated with human interferon- (IFN-) (Sigma-Aldrich Corporation, St. Louis, Mo.) and lipopolysaccharide from Salmonella minnesota (LPS) (Invivogen, San Diego, Calif.) to induce the expression of indoleamine 2, 3-dioxygenase (IDO1). Compounds with IDO1 inhibitory properties decreased the amount of kynurenine produced by the cells via the tryptophan catabolic pathway. Cellular toxicity due to the effect of compound treatment was measured using CellTiter-Glo reagent (CTG) (Promega Corporation, Madison, Wis.), which is based on luminescent detection of ATP, an indicator of metabolically active cells.

[0478] In preparation for the assays, test compounds were serially diluted 3-fold in DMSO from a typical top concentration of 5 mM and plated at 0.5 L in 384-well, polystyrene, clear bottom, tissue culture treated plates with lids (Greiner Bio-One, Kremsmunster, Austria) to generate 11-point dose response curves. Low control wells (0% kynurenine or 100% cytotoxicity) contained either 0.5 L of DMSO in the presence of unstimulated (-IFN-/-LPS) PBMCs for the mass spectrometry assay or 0.5 L of DMSO in the absence of cells for the cytotoxicity assay, and high control wells (100% kynurenine or 0% cytotoxicity) contained 0.5 L of DMSO in the presence of stimulated (+IFN-/+LPS) PBMCs for both the mass spectrometry and cytotoxicity assays.

[0479] Frozen stocks of PBMCs were washed and recovered in RPMI 1640 medium (Thermo Fisher Scientific, Inc., Waltham, Mass.) supplemented with 10% v/v heat-inactivated fetal bovine serum (FBS) (Thermo Fisher Scientific, Inc., Waltham, Mass.), and 1 penicillin-streptomycin antibiotic solution (Thermo Fisher Scientific, Inc., Waltham, Mass.). The cells were diluted to 1,000,000 cells/mL in the supplemented RPMI 1640 medium. 50 L of either the cell suspension, for the mass spectrometry assay, or medium alone, for the cytotoxicity assay, were added to the low control wells, on the previously prepared 384-well compound plates, resulting in 50,000 cells/well or 0 cells/well respectively. IFN- and LPS were added to the remaining cell suspension at final concentrations of 100 ng/ml and 50 ng/ml respectively, and 50 L of the stimulated cells were added to all remaining wells on the 384-well compound plates. The plates, with lids, were then placed in a 37 C., 5% CO.sub.2 humidified incubator for 2 days.

[0480] Following incubation, the 384-well plates were removed from the incubator and allowed to equilibrate to room temperature for 30 minutes. For the cytotoxicity assay, CellTiter-Glo was prepared according to the manufacturer's instructions, and 40 L were added to each plate well. After a twenty minute incubation at room temperature, luminescence was read on an EnVision Multilabel Reader (PerkinElmer Inc., Waltham, Mass.). For the mass spectrometry assay, 10 L of supernatant from each well of the compound-treated plates were added to 40 L of acetonitrile, containing 10 M of an internal standard for normalization, in 384-well, polypropylene, V-bottom plates (Greiner Bio-One, Kremsmunster, Austria) to extract the organic analytes. Following centrifugation at 2000 rpm for 10 minutes, 10 L from each well of the acetonitrile extraction plates were added to 90 L of sterile, distilled H.sub.2O in 384-well, polypropylene, V-bottom plates for analysis of kynurenine and the internal standard on the RapidFire 300 (Agilent Technologies, Santa Clara, Calif.) and 4000 QTRAP MS (SCIEX, Framingham, Mass.). MS data were integrated using Agilent Technologies' RapidFire Integrator software, and data were normalized for analysis as a ratio of kynurenine to the internal standard.

[0481] The data for dose responses in the mass spectrometry assay were plotted as % IDO1 inhibition versus compound concentration following normalization using the formula 100(100*((UC2)/(C1C2))), where U was the unknown value, C1 was the average of the high (100% kynurenine; 0% inhibition) control wells and C2 was the average of the low (0% kynurenine; 100% inhibition) control wells. The data for dose responses in the cytotoxicity assay were plotted as % cytotoxicity versus compound concentration following normalization using the formula 100(100*((UC2)/(C1C2))), where U was the unknown value, C1 was the average of the high (0% cytotoxicity) control wells and C2 was the average of the low (100% cytotoxicity) control wells.

[0482] Curve fitting was performed with the equation y=A+((BA)/(1+(10.sup.x/10.sup.c)D)), where A was the minimum response, B was the maximum response, C was the log(XC.sub.50) and D was the Hill slope. The results for each test compound were recorded as pIC50 values for the mass spectrometry assay and as pCC50 values for the cytoxicity assay (-C in the above equation).

TABLE-US-00002 TABLE 1 IDO1 PBMC example pIC.sub.50 1 8.1 2 8.1 3 8.0 4 8.4 5 8.1 6 8.0 7 8.2 8 8.2 9 8.3 10 8.3 11 8.3 12 8.5 13 8.1 14 8.4 15 8.4 16 9.1 17 8.1 18 8.2 19 8.4 20 8.7 21 8.8 22 8.7 23 8.4 24 8.5 25 8.5 26 8.1 27 8.0 28 8.1 29 8.8 30 8.0 31 8.1 32 8.0 33 8.1 34 8.4 35 8.2 36 8.8 37 8.6 38 8.3 39 8.3 40 8.4 41 8.4 42 8.3 43 9.0 44 8.5 45 8.5 46 8.4 47 8.4 48 8.4 49 8.2 50 8.2 51 8.1 52 8.0 53 8.5 54 7.9 55 7.9 56 7.9 57 7.9 58 7.9 59 7.9 60 7.9 61 7.9 62 7.9 63 7.9 64 7.9 65 7.9 66 7.9 67 7.9 68 7.8 69 7.8 70 7.8 71 7.8 72 7.8 73 7.8 74 7.8 75 7.8 76 7.8 77 7.8 78 7.8 79 7.8 80 7.8 81 7.8 82 7.8 83 7.8 84 7.7 85 7.7 86 7.7 87 7.7 88 7.7 89 7.7 90 7.7 91 7.7 92 7.7 93 7.7 94 7.7 95 7.7 96 7.7 97 7.6 98 7.6 99 7.6 100 7.6 101 7.6 102 7.6 103 7.6 104 7.6 105 7.6 106 7.6 107 7.5 108 7.5 109 7.5 110 7.5 111 7.5 112 7.5 113 7.5 114 7.5 115 7.5 116 7.5 117 7.5 118 7.5 119 7.5 120 7.4 121 7.4 122 7.4 123 7.4 124 7.4 125 7.4 126 7.4 127 7.4 128 7.4 129 7.4 130 7.3 131 7.3 132 7.3 133 7.3 134 7.3 135 7.3 136 7.3 137 7.3 138 7.2 139 7.2 140 7.2 141 7.2 142 7.2 143 7.1 144 7.1 145 7.1 146 7.1 147 7.1 148 7.1 149 7.1 150 7.1 151 7.1 152 7.1 153 7.1 154 7.1 155 7.1 156 7.1 157 7.0 158 7.0 159 7.0 160 7.0 161 7.0 162 7.0 163 7.0 164 7.0 165 7.0 166 7.0 167 7.0 168 7.0 169 7.0 170 7.0 171 7.0 172 7.0 173 6.9 174 6.9 175 6.9 176 6.9 177 6.9 178 6.9 179 6.9 180 6.9 181 6.8 182 6.8 183 6.8 184 6.8 185 6.8 186 6.8 187 6.8 188 6.8 189 6.7 190 6.7 191 6.7 192 6.7 193 6.7 194 6.6 195 6.6 196 6.6 197 6.6 198 6.6 199 6.5 200 6.5 201 6.5 202 6.5 203 6.5 204 6.5 205 6.5 206 6.5 207 6.4 208 6.4 209 6.4 210 6.4 211 6.4 212 6.4 213 6.4 214 6.4 215 6.4 216 6.3 217 6.3 218 6.3 219 6.3 220 6.3 221 6.3 222 6.3 223 6.3 224 6.3 225 6.3 226 6.2 227 6.2 228 6.2 229 6.2 230 6.2 231 6.2 232 6.1 233 6.1 234 6.1 235 6.1 236 6.0 237 6.0 238 6.0 239 6.0 240 6.0 241 6.0 242 6.0 243 6.0 244 6.0 245 6.0