Ethynyl derivatives

Abstract

The present invention relates to ethynyl derivatives of formula I ##STR00001##
with variables as defined herein, or to a pharmaceutically acceptable acid addition salt thereof. Compounds of formula I are metabotropic glutamate receptor antagonists (negative allosteric modulators) for use in the treatment of, e.g., anxiety and pain, depression, Fragile-X syndrome, autism spectrum disorders, Parkinson's disease, and gastroesophageal reflux disease (GERD).

Claims

1. A compound of formula I ##STR00019## or a pharmaceutically acceptable salt thereof, wherein: R.sup.1 is hydrogen or F; and n is 1 or 2.

2. A compound selected from the group consisting of: (1S,5R)-2-methyl-4-(5-(phenylethynyl)pyridin-2-yl)-2,4-diazabicyclo[3.2.O]heptan-3-one; (1R,5S)-2-(5-((4-fluorophenyl)ethynyl)pyridin-2-yl)-4-methyl-2,4-diazabicyclo[3.2.0] heptan-3-one; (1R,5S)-2-(5-((3-fluorophenyl)ethynyl)pyridin-2-yl)-4-methyl-2,4-diazabicyclo[3.2.0] heptan-3-one; and (1R,5S)-2-(5-((2,5-difluorophenyl)ethynyl)pyridin-2-yl)-4-methyl-2,4-diazabicyclo[3.2.0]heptan-3-one; or a pharmaceutically acceptable salt thereof.

3. The compound of claim 2, wherein the compound is (1S,5R)-2-methyl-4-(5-(phenylethynyl)pyridin-2-yl)-2,4-diazabicyclo[3.2.0] heptan-3-one; or a pharmaceutically acceptable salt thereof.

4. The compound of claim 2, wherein the compound is (1R,5S)-2-(5-((4-fluorophenyl)ethynyl)pyridin-2-yl)-4-methyl-2,4-diazabicyclo[3.2.O]heptan-3-one; or a pharmaceutically acceptable salt thereof.

5. The compound of claim 2, wherein the compound is (1R,5S)-2-(5-fluorophenyl)ethynyl)pyridin-2-yl)-4-methyl-2,4-diazabicyclo[3.2.O]heptan-3-one; or a pharmaceutically acceptable salt thereof.

6. The compound of claim 2, wherein the compound is (1R,5S)-2-(5-((2,5-difluorophenyl)ethynyl)pyridin-2-yl)-4-methyl-2,4-diazabicyclo[3.2.0]heptan-3-one; or a pharmaceutically acceptable salt thereof.

7. A pharmaceutical composition comprising a compound of claim 1, or a pharmaceutically acceptable salt thereof, and a therapeutically inert excipient.

8. A pharmaceutical composition comprising a compound of claim 2, or a pharmaceutically acceptable salt thereof, and a therapeutically inert excipient.

9. The pharmaceutical composition of claim 8, wherein the compound of the composition is (1S,5R)-2-methyl-4-(5-(phenylethynyl)pyridin-2-yl)-2,4-diazabicyclo[3.2.0]heptan-3-one, or a pharmaceutically acceptable salt thereof.

10. The pharmaceutical composition of claim 8, wherein the compound of the composition is (1R,5S)-2-(5-((4-fluorophenyl)ethynyl)pyridin-2-yl)-4-methyl-2,4-diazabicyclo[3.2.0]heptan-3-one, or a pharmaceutically acceptable salt thereof.

11. The pharmaceutical composition of claim 8, wherein the compound of the composition is (1R,5S)-2-(5-((3-fluorophenyl)ethynyl)pyridin-2-yl)-4-methyl-2,4-diazabicyclo[3.2.0]heptan-3-one, or a pharmaceutically acceptable salt thereof.

12. The pharmaceutical composition of claim 8, wherein the compound of the composition is (1R,5S)-2-(5-((2,5-difluorophenyl)ethynyl)pyridin-2-yl)-4-methyl-2,4-diazabicyclo[3.2.0]heptan-3-one, or a pharmaceutically acceptable salt thereof.

13. A method for the treatment of anxiety and pain, depression, Fragile-X syndrome, an autism spectrum disorder, Parkinson's disease, or gastro- esophageal reflux disease (GERD) in a patient, the method comprising administering to the patient in need thereof an effective amount of a compound of claim 1, or a pharmaceutically acceptable salt thereof.

14. A method for the treatment of anxiety and pain, depression, Fragile-X syndrome, an autism spectrum disorder, Parkinson's disease, or gastro- esophageal reflux disease (GERD) in a patient, the method comprising administering to the patient in need thereof an effective amount of a compound of claim 2, or a pharmaceutically acceptable salt thereof.

15. The method of claim 14, wherein the administered compound is (1S,5R)-2-methyl-4-(5-(phenylethynyl)pyridin-2-yl)-2,4-diazabicyclo[3.2.0]heptan-3-one, or a pharmaceutically acceptable salt thereof.

16. The method of claim 14, wherein the administered compound is (1R,5S)-2-(5((4-fluorophenyl)ethynyl)pyridin-2-yl)-4-methyl-2,4-diazabicyclo[3.2.0]heptan-3-one, or a pharmaceutically acceptable salt thereof.

17. The method of claim 14, wherein the administered compound is (1R,5S)-2-(5-((3-fluorophenyl)ethynyl)pyridin-2-yl)-4-methyl-2,4-diazabicyclo[3.2.0]heptan-3-one, or a pharmaceutically acceptable salt thereof.

18. The method of claim 14, wherein the administered compound is (1R,5S)-2-(5-((2,5-difluorophenyl)ethynyl)pyridin-2-yl)-4-methyl-2,4-diazabicyclo[3.2.0]heptan-3-one, or a pharmaceutically acceptable salt thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1: Comparison of an mGluR5 positive allosteric modulator (PAM) and an mGluR5 antagonist (negative allosteric modulator=NAM)

(2) FIG. 2: Activity of compound “Example 2” in the rat Vogel conflict drinking test.

EXAMPLES

(3) mGluR5-NAMs are beneficial for indications where a reduction of excessive receptor activity is desired, such as anxiety, pain, Fragile-X, autism spectrum disorders, and gastroeosophagal reflux disease. mGluR5 PAMs on the other hand are useful in indications where a normalisation of decreased receptor activity is desired such as in psychosis, epilepsy, schizophrenia, Alzheimer's disease and associated cognitive disorders, as well as tuberous sclerosis.

(4) This difference can be practically shown for example in an anxiety animal model such as the rat Vogel conflict drinking test where the compound of Example 1 shows anxiolytic activity at a minimal effective dose of 0.1 mg/Kg whereas mGluR-PAMs are not expected to show activity in this animal model (see FIG. 2).

Biological Assays and Data

Intracellular Ca.SUP.2+ Mobilization Assay

(5) A monoclonal HEK-293 cell line stably transfected with a cDNA encoding for the human mGlu5a receptor was generated; for the work with mGlu5 Positive Allosteric Modulators (PAMs), a cell line with low receptor expression levels and low constitutive receptor activity was selected to allow the differentiation of agonistic versus PAM activity. Cells were cultured according to standard protocols (Freshney, 2000) in Dulbecco's Modified Eagle Medium with high glucose supplemented with 1 mM glutamine, 10% (vol/vol) heat-inactivated bovine calf serum, Penicillin/Streptomycin, 50 μg/ml hygromycin and 15 μg/ml blasticidin (all cell culture reagents and antibiotics from Invitrogen, Basel, Switzerland).

(6) About 24 hrs before an experiment, 5×10.sup.4 cells/well were seeded in poly-D-lysine coated, black/clear-bottomed 96-well plates. The cells were loaded with 2.5 μM Fluo-4AM in loading buffer (1×HBSS, 20 mM HEPES) for 1 hr at 37° C. and washed five times with loading buffer. The cells were transferred into a Functional Drug Screening System 7000 (Hamamatsu, Paris, France), and 11 half logarithmic serial dilutions of test compound at 37° C. were added and the cells were incubated for 10-30 min with on-line recording of fluorescence. Following this pre-incubation step, the agonist L-glutamate was added to the cells at a concentration corresponding to EC.sub.20 (typically around 80 μM) with on-line recording of fluorescence; in order to account for day-to-day variations in the responsiveness of cells, the EC.sub.20 of glutamate was determined immediately ahead of each experiment by recording of a full dose-response curve of glutamate.

(7) Responses were measured as peak increase in fluorescence minus basal (i.e. fluorescence without addition of L-glutamate), normalized to the maximal stimulatory effect obtained with saturating concentrations of L-glutamate. Graphs were plotted with the % maximal stimulatory using XLfit, a curve fitting program that iteratively plots the data using Levenburg Marquardt algorithm. The single site competition analysis equation used was y=A+((B−A)/(1+((x/C)D))), where y is the % maximal stimulatory effect, A is the minimum y, B is the maximum y, C is the EC.sub.50, x is the log 10 of the concentration of the competing compound and D is the slope of the curve (the Hill Coefficient). From these curves the EC.sub.50 (concentration at which half maximal stimulation was achieved), the Hill coefficient as well as the maximal response in % of the maximal stimulatory effect obtained with saturating concentrations of L-glutamate were calculated.

(8) Positive signals obtained during the pre-incubation with the PAM test compounds (i.e. before application of an EC.sub.20 concentration of L-glutamate) were indicative of an agonistic activity, the absence of such signals were demonstrating the lack of agonistic activities. A depression of the signal observed after addition of the EC.sub.20 concentration of L-glutamate was indicative of an inhibitory activity of the test compound.

(9) In the list of examples below are shown the corresponding results for compounds which all have EC.sub.50 values less or equal 100 nM.

(10) WO2011128279=Ref. 1

(11) TABLE-US-00001 mGlu5 PAM Efficacy Example EC.sub.50 [nM] [%] Ref. 1; Ex. 106 30 42 Ref. 1; Ex. 109 18 37 Ex. 1 inactive Ex. 2 inactive Ex. 3 inactive Ex. 4 inactive

MPEP Binding Assay

(12) For binding experiments, cDNA encoding human mGlu5a receptor was transiently transfected into EBNA cells using a procedure described by Schlaeger and Christensen [Cytotechnology 15:1-13 (1998)]. Cell membrane homogenates were stored at −80° C. until the day of assay where upon they were thawed and resuspended and polytronised in 15 mM Tris-HCl, 120 mM NaCl, 100 mM KCl, 25 mM CaCl.sub.2, 25 mM MgCl.sub.2 binding buffer at pH 7.4 to a final assay concentration of 20 μg protein/well.

(13) Saturation isotherms were determined by addition of twelve [.sup.3H]MPEP concentrations (0.04-100 nM) to these membranes (in a total volume of 200 μl) for 1 h at 4° C. Competition experiments were performed with a fixed concentration of [.sup.3H]MPEP (2 nM) and IC.sub.50 values of test compounds evaluated using 11 concentrations (0.3-10,000 nM). Incubations were performed for 1 h at 4° C.

(14) At the end of the incubation, membranes were filtered onto unifilter (96-well white microplate with bonded GF/C filter preincubated 1 h in 0.1% PEI in wash buffer, Packard BioScience, Meriden, Conn.) with a Filtermate 96 harvester (Packard BioScience) and washed 3 times with cold 50 mM Tris-HCl, pH 7.4 buffer. Nonspecific binding was measured in the presence of 10 μM MPEP. The radioactivity on the filter was counted (3 min) on a Packard Top-count microplate scintillation counter with quenching correction after addition of 45 μl of microscint 40 (Canberra Packard S. A., Zürich, Switzerland) and shaking for 20 min.

(15) In the list of examples below are shown the corresponding results for compounds which all have EC.sub.50 values less or equal to 20 nM.

(16) TABLE-US-00002 mGlu5-MPEP binding Example EC.sub.50 (nM) Ref. 1; Ex. 106 8 Ref. 1; Ex. 109 12 1 9 2 5 3 4 4 3

(17) Comparison of the compounds of the invention versus the most similar compounds described in WO2011128279, examples 106 and 109.

(18) As can be seen in the table below, the compounds of the invention show a clearly different profile compared to structurally similar compounds of prior art which is an advantage when compounds showing NAM activity are desired.

(19) TABLE-US-00003 EC.sub.50 (nM) Ki (nM) Activity Ex. Structure mGlu5 PAM assay MPEP binding profile Ref. 1 Ex. 106 30 8 PAM Ref. 1 Ex. 109 18 37 PAM 1 inactive 9 NAM 2 inactive 5 NAM 3 inactive 4 NAM 4 inactive 3 NAM

(20) The compounds of formula I can be manufactured by the methods given below, by the methods given in the examples or by analogous methods. Appropriate reaction conditions for the individual reaction steps are known to a person skilled in the art. The reaction sequence is not limited to the one displayed in the schemes, however, depending on the starting materials and their respective reactivity the sequence of reaction steps can be freely altered. Starting materials are either commercially available or can be prepared by methods analogous to the methods given below, by methods described in references cited in the description or in the examples, or by methods known in the art.

(21) The present compounds of formula I and their pharmaceutically acceptable salts may be prepared by methods, known in the art, for example by the process variant described below, which process comprises

(22) reacting a compound of formula II

(23) ##STR00009##
wherein X is a halogen atom selected from bromine or iodine
with a suitable aryl-acetylene of formula III

(24) ##STR00010##
to form a compound of formula I

(25) ##STR00011##
wherein the substituent R.sup.1 is described above, in enantiomerically pure form with the absolute stereochemistry as drawn in formula I or by using II in racemic form followed by chiral separation of I to yield the optically pure enantiomer; and
if desired, converting the compounds obtained into pharmaceutically acceptable acid addition salts.

(26) The preparation of compounds of formula I is further described in more detail in schemes 1 to 3 and in examples 1-4.

(27) ##STR00012##

(28) The synthesis of compounds of formula IIa is described in scheme 1. A halo-pyridine compound of formula IIa can be obtained by a Palladium catalyzed reaction of an appropriate dihalogenated pyridine such as 2-bromo-5-iodo-pyridine with an appropriately substituted cyclic urea of formula 5 (scheme 1). Reaction of a 2-chloro- or 2-fluoro-pyridine having a bromine or iodine in position 5 with a bicyclic urea of formula 5 can also form a compound of formula IIa by an aromatic nuclophilic substitution reaction using basic conditions such as for example NaH/THF or Cesium carbonate/DMF. The compound of formula 5 can be obtained starting from an appropriately protected 2-amino-1-carboxylic acid of formula 1 which can be obtained using procedures similar to those described by Gorrea & al., Tetrahedron Asymmetry, 21, 339 (2010). The acid function of 1 is transformed via an acylazide intermediate into the corresponding isocyanate 2 (Curtius rearrangement) which then cyclizes to form the bicyclic urea compound 3. The free NH group of 3 can be methylated according to standard procedures to form compound 4 which is then deprotected to yield the cyclic urea 5. It is also possible to obtain optically pure intermediates 2 to 5 starting from an optically pure protected acid of formula 1 or by separation of the racemic mixture at any stage of the synthesis using procedures known to persons skilled in the art.

(29) ##STR00013##
Wherein R.sup.1 in this scheme means phenyl substituted by (R.sup.1).sub.n.

(30) The compound of formula IIa (X=Br, I) may react with a suitable aryl-acetylene of formula III (where W is either hydrogen or an in-situ cleavable protecting group such as a trialkylsilyl- or aryldialkylsilyl-group, preferably hydrogen or trimethylsilyl) under Palladium catalyzed coupling conditions (Sonogashira reaction) to form a compound of formula Ia, wherein the substituent R.sup.1 is described above. Another possibility consists of reacting IIa with trimethylsilyl acetylene to yield a compound of formula Ia where R.sup.1 is trimethylsilyl and then do a second Sonogashira reaction with an appropriate aryl bromide or aryl iodide to yield a compound of formula I (scheme not shown).

(31) In the case where the amino acid derivative 1 is in racemic form, the enantiomers can be separated at any given stage during the synthesis of compounds of formula I using procedures known to persons skilled in the art.

(32) It is also possible to invert the sequence of reactions leading to compounds of formula I (scheme 3). In this case, the Sonogashira reaction between the arylacetylene derivative III and the dihalo-pyridine is performed first to yield an arylacetylene-pyridine compound of formula 6 which is then condensed with the bicyclic urea 1 to yield compounds of formula I.

(33) ##STR00014##
Wherein R.sup.1 in this scheme means phenyl substituted by (R.sup.1).sub.n.

(34) The pharmacological activity of the compounds was tested using the following method:

(35) cDNA encoding rat mGlu 5a receptor was transiently transfected into EBNA cells using a procedure described by E.-J. Schlaeger and K. Christensen (Cytotechnology 1998, 15, 1-13). [Ca.sup.2+]i measurements were performed on mGlu 5a transfected EBNA cells after incubation of the cells with Fluo 3-AM (obtainable by FLUKA, 0.5 μM final concentration) for 1 hour at 37° C. followed by 4 washes with assay buffer (DMEM supplemented with Hank's salt and 20 mM HEPES. [Ca.sup.2+]i measurements were done using a fluorometric imaging plate reader (FLIPR, Molecular Devices Corporation, La Jolla, Calif., USA). When compounds were evaluated as antagonists they were tested against 10 μM glutamate as agonist.

(36) The inhibition (antagonists) curves were fitted with a four parameter logistic equation giving IC.sub.50, and Hill coefficient using the iterative non-linear curve fitting software Origin (Microcal Software Inc., Northampton, Mass., USA).

(37) The Ki values of the compounds tested are given. The Ki value is defined by the following formula:

(38) $K_i=\frac{{\mathrm{IC}}_{50}}{1+\frac{\left[L\right]}{{\mathrm{EC}}_{50}}}$
in which the IC.sub.50 values are those concentrations of the compounds tested in μM by which 50% of the effect of compounds are antagonized. [L] is the concentration and the EC.sub.50 value is the concentration of the compounds in μM which brings about 50% stimulation.

(39) The compounds of the present invention are mGluR 5a receptor antagonists. The activities of compounds of formula I as measured in the assay described above are in the range of K.sub.i<100 μM.

Synthetic Examples

Example 1

(−)-(1 S,5R)-2-methyl-4-(5-(phenylethynyl)pyridin-2-yl)-2,4-diazabicyclo[3.2.0]heptan-3-one

(40) ##STR00015##

Step 1: (rac)-(1SR,2RS)-2-(Naphthalen-2-ylmethoxycarbonylamino)cyclobutanecarboxylic acid methyl ester

(41) To a well stirred solution of (rac)-(cis)-(1RS,2SR)-cyclobutane-1,2-dicarboxylic acid monomethyl ester (CAS: 31420-52-7) (10.8 g, 68.3 mmol), and N-methylmorpholine (7.6 g, 8.26 ml, 75.1 mmol) in 160 ml of 1,2-dichloroethane was added dropwise diphenylphosphoryl azide (20.7 g, 16.2 ml, 75.1 mmol). After stirring for 10 min at room temperature, the reaction was warmed to 60° C. 2-Naphthylmethyl alcohol (10.8 g, 68.3 mmol) and copper(I)chloride (68 mg, 0.68 mmol) were added and the reaction was stirred for another 16 h at 60° C. The reaction was concentrated in vaccuo, the light brown oily residue (51 g) was diluted with 15 ml of dichloromethane and purified by flash chromatography on silicagel (SiO.sub.2 (650 g), Ethyl acetate/heptane 20:80) to yield 16.8 g of impure material containing unreacted naphthylmethanol. The material was repurified (Aminophase, 0% to 35% ethylacetate in heptane gradient) to yield 11.1 g (52%) of the title compound as a white crystalline solid, MS: m/e=314.2 (M+H.sup.+).

Step 2: (rac)-(1SR,2RS)-2-(Naphthalen-2-ylmethoxycarbonylamino)cyclobutanecarboxylic acid

(42) To a well stirred solution of (rac)-(1SR,2RS)-2-(naphthalen-2-ylmethoxycarbonylamino) cyclobutanecarboxylic acid methyl ester (Example 1, step 1) (4.2 g, 13.4 mmol), in 20 ml of dioxane was added water (70 ml). The solution was cooled to 5° C. and 53.6 ml (26.8 mmol) of 0.5M sodium hydroxide solution were added dropwise over a period of 5 min. After stirring for 1 h at 5° C., the reaction was allowed to warm up to room temperature with vigorous stirring. The clear solution was then cooled to 5° C. and the pH was adjusted to 2.5 by addition of ca. 13 ml 2N hydrochloric acid solution. The reaction was worked up with ethyl acetate. After drying, filtration and concentration in vaccuo, 3.87 g (97%) of the title compound was obtained as a crystalline white solid, MS: m/e=300.2 (M+H.sup.+).

Step 3: (rac)-(1RS,5SR)-3-Oxo-2,4-diaza-bicyclo[3.2.0]heptane-2-carboxylic acid naphthalen-2-ylmethyl ester

(43) A solution of (rac)-(1SR,2RS)-2-(naphthalen-2-ylmethoxycarbonylamino)cyclobutanecarboxylic acid (Example 1, step 2) (2.34 g, 7.82 mmol) and N-methylmorpholine (0.79 g, 0.86 ml, 7.82 mmol) in 34 ml of dichloroethane was stirred at r.t. for 10 min. Then diphenylphosphoric acid azide (2.15 g, 1.69 ml, 7.82 mmol) was added dropwise at room temperature and the colorless solution was stirred for 1 h at room temperature during which the solution turned light yellow. The solution was then warmed to 50° C., stirred for 6 h and allowed to cool. After workup with dichloromethane/water, the combined organic phases were evaporated to dryness to yield a yellow solid which was recrystallized from ethyl acetate/heptane. The title compound (1.86 g, 80%) was obtained as a white crystalline solid, MS: m/e=297.3 (M+H.sup.+).

Step 4: (rac)-(1RS,5SR)-4-Methyl-3-oxo-2,4-diaza-bicyclo[3.2.0]heptane-2-carboxylic acid naphthalen-2-ylmethyl ester

(44) To a solution of (rac)-(1RS,5SR)-3-Oxo-2,4-diaza-bicyclo[3.2.0]heptane-2-carboxylic acid naphthalen-2-ylmethyl ester (Example 1, step 3) (1.13 g, 3.81 mmol) in 11 ml of DMF was added a 60% suspension of sodium hydride in mineral oil (0.198 g, 4.96 mmol). The suspension was stirred for 35 minutes at room temperature (gas evolution), then iodomethane (0.81 g, 0.36 ml, 5.72 mmol) was added and the mixture was stirred at room temperature overnight. After quenching by addition of 3 ml sat. ammonium chloride solution and concentration in vaccuo, the residue was worked up with ethyl acetate/water. The combined organic phases were dried and concentrated in vaccuo. The residue was purified by flash chromatography on silicagel (50 g) eluting with a 20-100% ethyl acetate in heptane gradient to yield 0.98 g (82%) of a colorless oil, MS: m/e=311.2 (M+H.sup.+).

Step 5: (rac)-(1SR,5RS)-2-Methyl-2,4-diaza-bicyclo[3.2.0]heptan-3-one

(45) A solution of (rac)-(1RS,5SR)-4-Methyl-3-oxo-2,4-diaza-bicyclo[3.2.0]heptane-2-carboxylic acid naphthalen-2-ylmethyl ester (Example 1, step 4) (0.97 g, 3.13 mmol) in 15 ml of methanol was hydrogenated for 48 h over 10% Pd/C (0.333 g, 0.313 mmol). The solution was purged with argon, the catalyst was filtered off and washed with ethyl acetate. The filtrate was concentrated in vaccuo. The residue was purified by flash chromatography on silicagel (20 g) eluting with a 50-100% ethyl acetate in heptane gradient to yield 0.375 g (95%) of the title compound as a crystalline white solid, which was directly used in the next step without further characterisation.

Step 6: (rac)-(1RS,5SR)-2-(5-Iodo-pyridin-2-yl)-4-methyl-2,4-diaza-bicyclo[3.2.0]heptan-3-one

(46) To a solution of (rac)-(1SR,5RS)-2-methyl-2,4-diaza-bicyclo[3.2.0]heptan-3-one (Example 1, step 5) (375 mg, 2.97 mmol) and 2-fluoro-5-iodopyridine (683 mg, 3.06 mmol) in DMF (10 ml) was added a 60% suspension of sodium hydride in mineral oil (155 mg, 3.86 mmol). The reaction was stirred at room temperature overnight. After quenching by addition of 3 ml sat. ammonium chloride solution and concentration in vaccuo to eliminate the DMF, the residue was worked up with ethyl acetate/water. After drying and concentration in vaccuo, the residue was purified by flash chromatography (SiO.sub.2, 20 g) using a 0% to 65% ethyl acetate in heptane gradient. One obtains the title compound, (549 mg, 56%), as a crystalline white solid, MS: m/e=330.1 (M+H.sup.+).

Step 7: (rac)-(+/−)-(1SR, 5RS)-2-Methyl-4-(5-(phenylethynyl)pyridin-2-yl)-2,4-diazabicyclo[3.2.0]heptan-3-one

(47) In a 5 ml microwave tube were dissolved 110 mg (0.33 mmol) of (rac)-(1RS,5SR)-2-(5-iodo-pyridin-2-yl)-4-methyl-2,4-diaza-bicyclo[3.2.0]heptan-3-one (Example 1, step 6) in 1.5 ml DMF. Argon was bubbled through the solution. Ethynylbenzene (73 al, 68 mg, 0.67 mmol), Bis(triphenylphosphine)palladium(II) chloride (14 mg, 20 μmol), copper (I) iodide (1.9 mg, 10.0 μmol), Triphenylphosphine (1.8 mg, 7.7 μmol) and 107 μl of Triethylamine (101 mg, 140 al, 1.0 mmol) were added. The dark brown solution was stirred 3 h at 60° C. The reaction was worked up with ethyl acetate/water, dried and concentrated in vaccuo. The residue was purified by flash chromatography (silica gel, 20 g, 0% to 50% EtOAc in heptane gradient) to yield 95 mg (94%) of the title compound as a light brown crystalline solid, MS: m/e=304.2 (M+H.sup.+).

Step 8: (−)-(1S,5R)-2-Methyl-4-(5-(phenylethynyl)pyridin-2-yl)-2,4-diazabicyclo[3.2.0]heptan-3-one and (+)-(1R,5S)-2-methyl-4-(5-(phenylethynyl)pyridin-2-yl)-2,4-diazabicyclo[3.2.0]heptan-3-one

(48) The racemic mixture of (rac)-(+/−)-(1SR,5RS)-2-methyl-4-(5-(phenylethynyl)pyridin-2-yl)-2,4-diazabicyclo[3.2.0]heptan-3-one (Example 1, step 7) (95 mg) was separated by chiral HPLC: (Chiralpak AD®—5 cm×50 cm, 20 mM; 40% isopropanol/heptane, 35 ml/min, 18 Bar). Peak detection was realized using a UV-detector as well as an optical rotation detector (ORD) where one peak has a negative signal (the (−)-enantiomer), and the other peak has a positive signal (the (+)-enantiomer). The (−)-enantiomer, (−)-(1 S,5R)-2-methyl-4-(5-(phenylethynyl)pyridin-2-yl)-2,4-diazabicyclo[3.2.0]heptan-3-one (39 mg) was obtained as a crystalline light yellow solid, MS: m/e=304.1 (M+H.sup.+). The (+)-enantiomer, (−)-(1R,5S)-2-methyl-4-(5-(phenylethynyl)pyridin-2-yl)-2,4-diazabicyclo[3.2.0]heptan-3-one (40 mg) was obtained as a light yellow solid, MS: m/e=304.1 (M+H.sup.+).

Example 2

(−)-(1R,5S)-2-[5-(3-Fluoro-phenylethynyl)-pyridin-2-yl]-4-methyl-2,4-diazabicyclo[3.2.0]heptan-3-one

(49) ##STR00016##

(50) The title compound was prepared in accordance with the general method of Example 1, step 7 starting from (rac)-(1RS,5SR)-2-(5-iodo-pyridin-2-yl)-4-methyl-2,4-diaza-bicyclo[3.2.0]heptan-3-one (Example 1, step 6) (110 mg) and 1-ethynyl-3-fluorobenzene to yield 107 mg (96%) of racemic material ((+/−)-(1R,5S)-2-[5-(3-fluoro-phenylethynyl)-pyridin-2-yl]-4-methyl-2,4-diazabicyclo[3.2.0]heptan-3-one as a light yellow crystalline solid; MS: m/e=322.3 (M+H.sup.+) which was then separated by chiral HPLC using similar separation conditions as described in example 1, step 8 to yield the enantiomerically pure enantiomers (−)-(1R,5S)-2-[5-(3-fluoro-phenylethynyl)-pyridin-2-yl]-4-methyl-2,4-diazabicyclo[3.2.0] heptan-3-one as a light yellow solid, MS: m/e=322.3 (M+H.sup.+); and its enantiomer (+)-(1S,5R)-2-[5-(3-fluoro-phenylethynyl)-pyridin-2-yl]-4-methyl-2,4-diazabicyclo[3.2.0] heptan-3-one as a light yellow solid; MS: m/e=322.3 (M+H.sup.+).

Example 3

(−)-(1R,5S)-2-[5-(4-Fluoro-phenylethynyl)-pyridin-2-yl]-4-methyl-2,4-diazabicyclo[3.2.0]heptan-3-one

(51) ##STR00017##

(52) The title compound was prepared in accordance with the general method of Example 1, step 7 starting from (rac)-(1RS,5SR)-2-(5-iodo-pyridin-2-yl)-4-methyl-2,4-diaza-bicyclo[3.2.0]heptan-3-one (Example 1, step 6) (110 mg) and 1-ethynyl-4-fluorobenzene to yield 104 mg (97%) of racemic material ((+/−)-(rac)-(1SR,5RS)-2-[5-(4-fluoro-phenylethynyl)-pyridin-2-yl]-4-methyl-2,4-diazabicyclo[3.2.0] heptan-3-one as a light yellow crystalline solid; MS: m/e=322.3 (M+H.sup.+) which was then separated by chiral HPLC using similar separation conditions as described in example 1, step 8 to yield the enantiomerically pure enantiomers (−)-(1R,5S)-2-[5-(4-fluoro-phenylethynyl)-pyridin-2-yl]-4-methyl-2,4-diazabicyclo[3.2.0]heptan-3-one as a light yellow solid, MS: m/e=322.3 (M+H.sup.+); and its enantiomer (+)-(1 S,5R)-2-[5-(4-fluoro-phenylethynyl)-pyri din-2-yl]-4-methyl-2,4-diazabicyclo[3.2.0]heptan-3-one as a light yellow solid; MS: m/e=322.3 (M+H.sup.+).

Example 4

(−)-(1R,5S)-2-[5-(2,5-Difluoro-phenylethynyl)-pyridin-2-yl]-4-methyl-2,4-diazabicyclo[3.2.0]heptan-3-one

(53) ##STR00018##

(54) The title compound was prepared in accordance with the general method of Example 1, step 7 starting from (rac)-(1RS,5SR)-2-(5-iodo-pyridin-2-yl)-4-methyl-2,4-diaza-bicyclo[3.2.0]heptan-3-one (Example 1, step 6) (110 mg) and 2-ethynyl-1,4-difluorobenzene to yield 110 mg (97%) of racemic material ((+/−)-(rac)-(1SR,5RS)-2-[5-(2,5-difluoro-phenylethynyl)-pyridin-2-yl]-4-methyl-2,4-diazabicyclo[3.2.0] heptan-3-one as a light yellow crystalline solid; MS: m/e=340.1 (M+H.sup.+) which was then separated by chiral HPLC using similar separation conditions as described in example 1, step 8 to yield the enantiomerically pure enantiomers (−)-(1R,5S)-2-[5-(2,5-difluoro-phenyl-ethynyl)-pyridin-2-yl]-4-methyl-2,4-diazabicyclo[3.2.0]heptan-3-one as a light yellow solid, MS: m/e=340.1 (M+H.sup.+); and its enantiomer (+)-(1 S,5R)-2-[5-(2,5-difluoro-phenyl-ethynyl)-pyridin-2-yl]-4-methyl-2,4-diazabicyclo[3.2.0]heptan-3-one as a light yellow solid; MS: m/e=340.1 (M+H.sup.+).

Preparation of the Pharmaceutical Compositions

Example I

(55) Tablets of the following composition are produced in a conventional manner:

(56) TABLE-US-00004 mg/Tablet Active ingredient 100 Powdered lactose 95 White corn starch 35 Polyvinylpyrrolidone 8 Na carboxymethylstarch 10 Magnesium stearate 2 Tablet weight 250

Example II

(57) Tablets of the following composition are produced in a conventional manner:

(58) TABLE-US-00005 mg/Tablet Active ingredient 200 Powdered lactose 100 White corn starch 64 Polyvinylpyrrolidone 12 Na carboxymethylstarch 20 Magnesium stearate 4 Tablet weight 400

Example III

(59) Capsules of the following composition are produced:

(60) TABLE-US-00006 mg/Capsule Active ingredient 50 Crystalline lactose 60 Microcrystalline cellulose 34 Talc 5 Magnesium stearate 1 Capsule fill weight 150

(61) The active ingredient having a suitable particle size, the crystalline lactose and the microcrystalline cellulose are homogeneously mixed with one another, sieved and thereafter talc and magnesium stearate are admixed. The final mixture is filled into hard gelatine capsules of suitable size.