Azasteroidal mimics

Abstract

An azasteroid mimic or an intermediate for the preparation of an azasteroid and azasteroid mimic is formed via an oxocycloalkenyl isoxazolium anhydrobase and its dimer. The dimer can be used to form mono- and dihydrazones, which can be an azasteroid mimic or an intermediate for the preparation of an azasteroid and azasteroid mimic. A method of preparation of the dimer and the azasteroid mimic or an intermediate for the preparation of an azasteroid and azasteroid mimic occurs with hydrazonation and, optionally, a subsequent dehydrazonation. The dimer can be converted by inserting a nitrogen atom into the six membered ring of to a C-17 position cyclohexenone moiety of the dimer to yield a reduced tetrazolo[1,5-a]azepin-8-yl group. A subsequent hydrozone formation at a benzylic ketone can be carried out to generate an azasteroid mimic with a (triazol-4-yl)imino substituent. Monohydrazones can be converted to their thione equivalents.

Claims

1. An azasteroid mimic or intermediate for the preparation of an azasteroid and azasteroid mimic, consisting of an oxocycloalkenyl isoxazolium anhydrobase, or any salt thereof, where the oxocycloalkenyl isoxazolium anhydrobase is a modified dimer of ##STR00026## having the structure: ##STR00027## where independently, XO, ##STR00028## wherein at least one X is not O; or a ring-expanded dimer of the structure: ##STR00029## wherein X is O or ##STR00030##

2. The azasteroid mimic or intermediate for the preparation of an azasteroid or azasteroid mimic according to claim 1, wherein the azasteroid mimic is a monohydrazone of the structure: ##STR00031##

3. The azasteroid mimic or intermediate for the preparation of an azasteroid or azasteroid mimic according to claim 1, wherein the modified dimer is a monohydrazone of the structure: ##STR00032##

4. The azasteroid mimic or intermediate for the preparation of an azasteroid or azasteroid mimic according to claim 1, wherein the modified dimer is a dihydrazone of the structure: ##STR00033##

5. The azasteroid mimic or intermediate for the preparation of an azasteroid and azasteroid mimic, according to claim 1, wherein the structure is: ##STR00034##

6. The azasteroid mimic or intermediate for the preparation of an azasteroid and azasteroid mimic, according to claim 1, wherein the structure is: ##STR00035##

7. The azasteroid mimic or intermediate for the preparation of an azasteroid and azasteroid mimic, according to claim 1, wherein the structure is: ##STR00036##

8. The azasteroid mimic or intermediate for the preparation of an azasteroid and azasteroid mimic, according to claim 1, wherein the structure is: ##STR00037##

9. A method of preparing an azasteroid mimic or intermediate for the preparation of an azasteroid or azasteroid mimic according to claim 1, comprising: providing an oxocycloalkenyl isoxazolium anhydrobase of the structure: ##STR00038## dimerizing the oxocycloalkenyl isoxazolium anhydrobase to a dimer of the structure: ##STR00039## optionally, selectively ring-expanding the cycloheneyl ketone with trimethylsilyl azide and trimethylsilyl triflates to form a dimer of the structure: ##STR00040## reacting the dimer with one or two equivalents of 4-amino-4H-1,2,4-tirazole to a first monohydrazone, a dihydrazone, or mixture thereof optionally, in the presence of a ketone activating catalyst; optionally, transforming the ketone of the first monohydrazone to a thione of the structure: ##STR00041## optionally, dehydrazonating the dihydrazone to a second monohydrazone; and isolating the azasteroid mimic or intermediate for the preparation of an azasteroid or azasteroid mimic.

10. The method of claim 9, wherein the ketone activating catalyst is titanium isopropoxide, cerium (III) chloride or scandium triflates.

11. The method of claim 9, wherein the ketone activating catalyst is scandium triflates.

12. The method of claim 9, wherein the 4-amino-4H-1,2,4-tirazole is added in a first addition and the ketone activating catalyst is added after formation of the monohydrazone to convert at least a portion of the monohydrazone to a dihydrazone.

13. The method of claim 9, wherein the dehydrazonating is catalyzed by cupric chloride.

14. The method of claim 9, wherein the transforming to a thione is reacting with Lawesson's reagent.

Description

DETAILED DISCLOSURE

(1) Embodiments of the invention are directed to the preparation of an intermediate benz[e]indenedione 46 and the preparation of novel azasteroids and azasteroid mimics therefrom. A facile process starts with commercially available starting materials, for example, but not limited to, 3,5-dimethylisoxazole 42 and carbocyclic vinylogous ester 43, to yield an enone product 44 which is subsequently converted into the corresponding oxocycloalkenyl isoxazolium anhydrobase 45, as indicated in Scheme 1, below.

(2) ##STR00016##

(3) In this example, the lithiation of 3,5-dimethylisoxazole 42 with n-ButyLi in THF at 78 C. was performed according to Micetich., Can. J. Chem. 1970, 48 (13), 2006-15. The lithiated intermediate participates in a nucleophilic reaction by addition of 3-ethoxy-2-cyclohexen-1-one 43. After acidification of the reaction mixture with 2N HCl, the corresponding enone 44 is obtained in good yield. N-alkylation of enone 44 with trimethyloxonium tetrafluoroborate followed by deprotonation with addition of a solution of n-BuLi in THF at 78 C. afforded the desired anhydrobase 45, where either geometric isomer or a mixture of both can be formed. The new tricyclic benz[e]indenedione 46, a compound produced via initial dimerization of the anhydrobase, was formed when warming 45 in benzene at 50 C. The compound is formed as a pair of enantiomers, which can be separated by chiral chromatography or by formation of diastereomers with a chiral reagent, for example, formation of ammonium salts of a chiral acid, and crystallization.

(4) The dimer 46 provides a platform to establish a six membered A-ring (or a mimic there of) of a steroidal skeleton. Moreover, a dimer such as 46 contains interesting functionality at C-17 along with never before explored vinylogous amide functionality at C-15 and C-16. Specifically, the dimer 46 can be envisioned to afford 1,2-diazasteroid (pyridazinone) 47 and azasteroidal mimic compounds 48 and 49, as shown below. However, the benzylic ketone of 46 is not particularly reactive as the aromatic ring does not provide any additional advantage over other reactive sites on dimer 46 such as the cyclohexenone, the enaminone, and the tertiary benzylic hydrogen present on the five-membered ring.

(5) ##STR00017##

(6) To increase the reactivity of the benzylic ketone, the hydrazone formation reaction is carried out in the presence of a ketone activating catalyst, such as, but not limited to, titanium isopropoxide, cerium (III) chloride and scandium triflate. In this manner, triazole reacts with both ketones of dimer 46 to yield about 30% of monohydrazone product (75) (reacting at cyclohexenone carbonyl) and about 30% of bishydrazone product (76), as shown in Scheme 2 below.

(7) ##STR00018##

(8) Higher yield was afforded by adding the ketone activating catalyst after formation of the kinetically favored 75, which increases the yield bishydrozone 76, as shown in Scheme 3, below.

(9) ##STR00019##

(10) In like manner to the hydrozone formation from dimer 46, the dehydrazonation reaction of bishydrozone 76, as shown in Scheme 4, below, allows the selective removal of the hydrozone to afford the desired monohydrozone 48.

(11) ##STR00020##

(12) All of the compounds above are potential drugs or intermediates in the synthesis for drugs and other biologically active compounds. The reaction intermediates can be modified at any carbon, nitrogen or oxygen in the compounds.

(13) In an embodiment of the invention, regiospecific ring expansion conditions, as taught in Magnus et al. J. Chem. Soc. Perkin Trans 1. 1991, 2657-59, is performed on dimer 46, such as treatment of dimer with excess of trimethylsilyl azide and trimethylsilyl triflate, provide compound 80 having a hetero bicyclic ring structure at C-17 position by inserting a nitrogen atom into the six membered ring of cyclohexenone moiety of dimer, as shown in Scheme 5, below. The other benzylic ketone of dimer 46, does not compete, presumably due to the steric influence of a methyl group present on the aromatic ring. This unreacted benzylic ketone undergoes hydrozone formation upon heating with 4-amino-4H-1,2,4-triazole in the presence of a ketone activating catalyst such as scandium triflate, to introduce a triazole ring moiety, which mimics the tetracyclic core of azasteroids, and provides the azasteroidal compound 81.

(14) ##STR00021##

(15) Azasteroidal compound 81 has the capacity of binding the active site of the enzyme CYP17A1 similar to Abiraterone, of the structure:

(16) ##STR00022##

(17) Compound 81 has the capacity like VT-1161 (a novel oral agent synthesized by Viamet) to treat onychomycosis, a very common fungal infection of the nail. VT-1161, shown below, is a tetrazole derivative. Lanosterol 14-demethylase (CYP51A1) is an enzyme responsible for the production of ergosterol. This steroid, in animals, alters the rigidity and permeability of plasma membrane of cells. Because ergosterol constitutes a fundamental component of fungal membranes, 14-demethylase is a target for antifungal agents. Azoles are the most popular and widely used antifungal agents in both agriculture and medicine. These compounds bind as the sixth ligand to the heme group in CYP51, thereby altering the structure of the active site and acting as noncompetitive inhibitor.

(18) ##STR00023##

(19) In an embodiment of the invention, as schematically illustrated from compound 81 in scheme 6, the thione, compound 82 can be prepared using Lawesson's reagent. In like manner, the thione:

(20) ##STR00024##
can be formed from compound 76.

(21) ##STR00025##

(22) The azasteroidal mimic compounds are potentially biologically active, and have characteristics that suggest activity, as in the compound, abiraterone acetate (Zytiga), which is an antiandrogen used in the management of castration-resistant prostate cancer. The compounds herein can be used as drugs, prodrugs or for other uses. The compounds herein can be formulated in various manners for administration in a variety of ways.

Methods and Materials

3-((3-methylisoxazol-5-yl)methyl)cyclohex-2-ene-1-one (44)

(23) 3,5-Dimethylisoxazole 42 (5.0 g, 51.5 mmol) was dissolved in 50 ml dry THF and kept at 78 C. 22.6 ml (1.1 eq) of 2.5 M n-BuLi in hexane was added via cannula to the above mixture over 20 min. After stirring for 30 min, at the same temperature, 3-ethoxycyclohex-2-ene-1-one 43 (7.2 g, 51.5 mmol) was added in one lot with vigorous stirring. The reaction mixture was slowly brought back to the RT, stirred for 30 min and acidified with 35 ml of 2N HCl, which is then extracted with aqueous ammonium chloride and diethyl ether/chloroform. The organic layer was dried, evaporated and purified with silica gel column chromatography by using 4:1 hexane:ethyl acetate starting with pure hexane and slowly increased the polarity with ethyl acetate as eluent. 7.02 g of light orange colored liquid product (71%) was obtained. .sup.1H NMR: (400 MHz, CDCl.sub.3): 5.92 (s, 1H), 5.90 (t, J=1.2 Hz, 1H), 3.62 (s, 2H), 2.38 (t, J=6.8 Hz, 2H), 2.33 (t, J=5.8 Hz, 2H), 2.28 (s, 3H), 2.01 (m, 2H). .sup.13C NMR: (400 MHz, CDCl.sub.3): 199.17, 167.88, 160.04, 158.86, 127.88, 103.47, 37.12, 35.04, 29.26, 22.52, 11.39.

3-((2,3-dimethylisoxazol-5(2H)-ylidene)methyl)cyclohex-2-en-1-one (45)

(24) Trimethyloxonium tetrafluoroborate (5.48 g, 36.6 mmol) and 3-((3-methylisoxazol-5-yl)methyl)cyclohex-2-ene-1-one (7.0 g, 36.6 mmol) were added into a two-neck dried flask, which is then stirred under argon until no solid remained. The reaction flask was evacuated, refilled with argon and kept at 78 C. To this reaction mixture, a solution of 16.1 ml of n-BuLi (2.5 M in hexane) in 60 ml of dry THF was added dropwise by using cannula over 30 min period. The reaction flask was slowly brought back to RT over a period of 90 min. A balloon, filled with argon gas, was kept on top of reaction flask's septum to release excess pressure. After stirring 10 min at RT 40 ml of water was added and the resulting solution extracted with chloroform (three times). The organic layers were combined, dried with anhydrous magnesium sulfate and filtered. The solvent was removed under vacuum in dark without heat. The resulting crude compound was purified with silica gel column chromatography by using 9:1 CHCl.sub.3:MeOH starting with pure chloroform and slowly increased the polarity with methanol as eluent to yield 7.1 g (74%) of dark yellow colored solid product. .sup.1H NMR: (400 MHz, CDCl.sub.3): 6.15 (s, 1H), 5.43 (s, 1H), 4.82 (s, 1H), 3.23 (s, 3H), 2.47 (t, J=6.0 Hz, 2H), 2.35 (t, J=6.6 Hz, 2H), 2.07 (d, J=0.4 Hz, 3H), 1.97 (m, 2H). .sup.13C NMR: (400 MHz, CDCl.sub.3): 198.3, 165.7, 158.7, 155.3, 116.6, 100.7, 88.1, 39.4, 36.6, 30.0, 22.6, 10.9.

5-methyl-2-(1-(methylamino)ethylidene)-3-(3-oxocyclohex-1-en-1-yl)-2,3,8,9-tetrahydro-1H-cyclopenta[a]naphthalene-1,6(7H)-dione (46):

(25) 3-((2,3-Dimethylisoxazol-5(2H)-ylidene)methyl)cyclohex-2-en-1-one 45 (5.0 g, 24.3 mmol) was dissolved in 25 ml of anhydrous benzene and heated at 50 C. for 3 hours. The crude solvent was evaporated under vacuum and chromatographed on silica gel with 4:1 hexane:ethyl acetate starting with pure hexane and slowly increased the polarity with ethyl acetate as eluent to get pure red colored solid product (12% yield). .sup.1H NMR: (400 MHz, CDCl.sub.3): 10.90 (d, J=4.8 Hz, 1H), 7.02 (s, 1H), 6.33 (s, 1H), 4.38 (s, 1H), 3.64 (t, J=6.0 Hz, 2H), 3.03 (d, J=5.2 Hz, 3H), 2.69-2.66 (m, 5H), 2.38 (m, 2H), 2.11 (m, 2H) 2.02 (s, 3H), 1.98 (m, 2H), 1.78 (m, 2H). .sup.13C NMR: (400 MHz, CDCl.sub.3): 200.10, 199.73, 190.58, 167.05, 161.68, 151.18, 145.12, 144.83, 135.50, 131.69, 128.18, 126.07, 105.62, 50.97, 41.06, 37.80, 29.64, 25.46, 24.37, 24.17, 23.00, 22.59, 15.39. LRMS: (LC/MS, MeOH) m/e 364.19 (MH.sup.+).

3-(3-((4H-1,2,4-triazol-4-yl)imino)cyclohex-1-en-1-yl)-5-methyl-2-(1-(methylamino)ethylidene)-2,3,8,9-tetrahydro-1H-cyclopenta[a]naphthalene-1,6(7H)-dione (75)

(26) The dimer compound 46 (0.1 g, 0.27 mmol) was heated with 2 eq of 4-amino-4H-1,2,4-tirazole (46 mg, 0.55 mmol) at 100 C. for 1 h. The reaction was carried out without any solvent. The crude compound was then purified with silica gel column chromatography 9:1 CHCl.sub.3:MeOH starting with pure chloroform and slowly increased the polarity with methanol in order to obtain pure product of both isomers in the ratio of 2:1 (83 mg, 71%). .sup.1H NMR: (400 MHz, CDCl.sub.3): 10.90 (m, 1H), 8.27 and 8.22 (s, 2H), 7.06 and 6.86 (s, 1H), 6.68 and 6.35 (s, 1H), 4.47 and 4.27 (s, 1H), 3.64 (m, 21H), 3.04 (d, J=5.6, 3H), 2.69 (m, 5H), 2.44 (m, 2H), 2.07 (s, 3H), 2.12 (m, 2H), 2.01 (m, 2H), 1.78 (m, 2H). .sup.13C NMR: (400 MHz, CDCl.sub.3): 200.07, 199.99, 190.52, 190.39, 173.18, 173.08, 166.69, 161.70, 161.57, 161.30, 151.15, 150.57, 145.15, 145.06, 144.95, 144.87, 139.90, 139.70, 135.46, 131.82, 131.68, 125.93, 125.70, 124.06, 123.82, 115.44, 105.44, 105.41, 51.34, 50.97, 41.00, 31.49, 29.61, 27.05, 26.34, 25.42, 24.90, 24.16, 24.01, 22.54, 22.50, 22.19, 21.97, 15.43, 15.32. LRMS: (LC/MS, MeOH) m/e 430.22 (MH.sup.+).

6-((4H-1,2,4-triazol-4-yl)imino)-3-(3-((4H-1,2,4-triazol-4-yl)imino)cyclohex-1-en-1-yl)-5-methyl-2-(1-(methylamino)ethylidene)-2,3,6,7,8,9-hexahydro-1H-cyclopenta[a]naphthalen-1-one (76)

(27) The dimer compound 46 (1.0 g, 2.75 mmol) was heated with 4-amino-4H-1,2,4-tirazole (0.92 g, 10.9 mmol) at 100 C. for 3 h in presence of 15 mole percent scandium triflate (0.2 g) as a catalyst. After reaction, the crude compound was chromatographed on silica gel column using 9:1 CHCl.sub.3/MeOH starting with pure chloroform and slowly increased the polarity with methanol) as an eluent to obtain pure bis-hydrazone compound (0.4 g, 30% yield) along with the monohydrazone compound (0.41 g, 35% yield). .sup.1H NMR: (400 MHz, CDCl.sub.3): 10.93 (m, 1H), 8.24 (t, 4H), 7.17 and 6.97 (s, 1H), 6.70 and 6.36 (s, 1H) 4.50 and 4.29 (s, 1H), 3.63 (m, 3.50 (m, 1H), 3.04 (m, 3H), 2.71 (m, 2H), 2.80 (s, 3H) 2.45 (m, 2H), 2.09 (s, 3H), 1.90 (m, 4H), 1.63 (m, 2H). .sup.13C NMR: (400 MHz, CDCl.sub.3): 190.20, 190.07, 175.24, 175.11, 173.10, 166.63, 161.97, 161.61, 150.15, 149.57, 142.88, 142.81, 142.53, 142.42, 139.97, 139.76, 139.61, 135.25, 135.19, 130.29, 130.10, 126.31, 126.04, 123.95, 115.53, 105.52, 51.30, 50.93, 31.53, 29.75, 29.71, 29.28, 27.12, 24.96, 24.84, 24.36, 24.31, 24.04, 22.25, 22.05, 21.46, 15.57, 15.46, 14.15. LRMS: (LC/MS, MeOH) m/e 496.26 (MH.sup.+).

6-((4H-1,2,4-triazol-4-yl)imino)-5-methyl-2-(1-(methylamino)ethylidene)-3-(3-oxocyclohex-1-en-1-yl)-2,3,6,7,8,9-hexahydro-1H-cyclopenta[a]naphthalen-1-one (48)

(28) Cupric chloride (27 mg, 0.2 mmol) dissolved in 4 ml of water was added dropwise to the solution of bis-hydrazone compound 76 (0.1 g, 0.2 mmol) dissolved in 3 ml of THF at RT. The reaction process was carefully followed by TLC and the dimer compound started forming after 10 hours of stirring, which indicated that the dehydrozination on tetralone hydrazone moiety started after 10 h of stirring and the reaction was stopped. The crude compound was partitioned between ammonium hydroxide and chloroform. The organic layer was then evaporated and chromatographed on silica gel column using 9:1 CHCl.sub.3:MeOH starting with pure chloroform and slowly increasing polarity with methanol as an eluent to obtain pure product (28 mg, 33% in yield). .sup.1H NMR: (400 MHz, CDCl.sub.3): 10.90 (d, J=5.2, 1H), 8.23 (s, 2H), 7.12 (s, 1H), 6.32 (s, 1H), 4.39 (s, 1H), 3.64-3.55 (m, 1H), 3.51-3.43 (m, 1H), 3.03 (d, J=5.2, 3H), 2.70 (t, J=6.8, 2H), 2.65 (s, 3H) 2.36 (m, 2H), 2.02 (s, 3H), 1.95 (m, 2H), 1.82 (m, 2H), 1.61 (m, 2H). .sup.13C NMR: (400 MHz, CDCl.sub.3): 199.63, 190.09, 175.22, 166.86, 161.98, 150.09, 142.72, 142.26, 139.53, 135.19, 129.98, 128.13, 126.32, 105.61, 50.81, 37.72, 29.61, 29.19, 24.63, 24.35, 24.27, 22.95, 21.39, 15.36. LRMS: (LC/MS, MeOH) m/e 430.22 (MH.sup.+).

(Z)-3-(6,7-dihydro-5H-tetrazolo[1,5-a]azepin-8-yl)-5-methyl-2-(1-(methylamino)ethylidene)-2,3,8,9-tetrahydro-1H-cyclopenta[a]naphthalene-1,6(7H)-dione (80)

(29) To a solution of dimer 46 (50 mg, 1 eq) in 2 ml of anhydrous dichloromethane was added azidotrimethyl silane (47 mg, 3 eq) and trimethylsilyl triflate (92 mg, 3eq) at rt and stirred for 1 h. The reaction progress was carefully followed by TLC and quenched with water when TLC showed no spot of dimer compound. The resulting reaction mixture was extracted with dichloromethane and dried over anhydrous magnesium sulfate. The residue formed on evaporation was purified by silica gel column chromatography with chloroform to obtain pure product 80 (25 mg, 45%) as red colored solid.

(30) .sup.1H NMR: (400 MHz, CDCl.sub.3): 10.90 (d, J=5.2, 1H), 7.12 (s, 1H), 7.07 (s, 1H), 4.55-4.48 (m, 3H), 3.65 (m, 2H), 3.05 (d, J=5.2, 3H), 2.68 (m, 5H), 2.12 (t, J=7.2, 2H), 2.06 (s, 3H), 1.95 (m, 4H).

(31) .sup.13C NMR: (100 MHz, CDCl.sub.3): 200.08, 190.64, 161.90, 154.64, 151.38, 151.31, 145.24, 144.90, 135.40, 131.81, 125.97, 111.69, 105.52, 53.16, 49.69, 48.53, 41.04, 40.26, 31.32, 29.64, 28.40, 25.48, 24.14, 22.98, 22.59, 15.63, 15.41.

(2Z,6E)-6-((4H-1,2,4-triazol-4-yl)imino)-3-(6,7-dihydro-5H-tetrazolo[1,5-a]azepin-8-yl)-5-methyl-2-(1-(methylamino)ethylidene)-2,3,6,7,8,9-hexahydro-1H-cyclopenta[a]naphthalen-1-one (81):

(32) A mixture of compound 80 (25 mg, 1 eq) and excess of 4-amino-4H-1,2,4-tirazole (20 mg) was heated at 100 C. for 3 h in the presence of scandium triflate (15 mol %). The resulting reaction residue was purified by silica gel column chromatography with chloroform/methanol (9:1) to obtain corresponding pure hydrazone 81 (8 mg, 30%) as a red solid product.

(33) .sup.1H NMR: (400 MHz, CDCl.sub.3): 10.97 (d, J=5.2, 1H), 8.27 (d, 2H), 7.19 (s, 1H), 7.15 (s, 1H), 4.62-4.51 (m, 3H), 3.65 (m, 2H), 3.05 (d, J=5.2, 3H), 2.61 (m, 5H), 2.11 (t, J=7.2, 2H), 2.08 (s, 3H), 1.92 (m, 4H).

(34) .sup.13C NMR: (100 MHz, CDCl.sub.3): 190.24, 175.16, 162.21, 154.52, 151.36, 150.29, 142.92, 142.40, 139.57, 135.15, 130.20, 126.83, 126.28, 111.77, 105.56, 53.10, 49.68, 29.69, 29.27, 28.45, 25.04, 24.90, 24.70, 24.37, 23.00, 21.47, 21.33, 15.46.

(35) HRMS: (LC/MS, MeOH) m/z 470.24 (MH.sup.+).

(36) All publications referred to or cited herein are incorporated by reference in their entirety, including all figures and tables, to the extent they are not inconsistent with the explicit teachings of this specification.

(37) It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application.