CA1125278A - Intermediate isoxazoles - Google Patents

Abstract

A B S T R A C T
Intermediate isoxazoles are used in the preparation of 2.alpha.-cyano 3-oxosteroids having a 4.alpha.,5.alpha.-epoxy group and being alkylated in the 4- and/or 6-position. The intermedi-ates are prepared by epoxidizing the double bond in a corre sponding unsaturated isoxazol. Some species of the present intermediates are useful in disrupting pregnancy in female mammals.

Description

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-This invention relates to intermediates of novel 2a-cyano-3-oxo-steroids having a 4a,5a-epoxy group and alkyl-ated in the 4- and/or 6 position as described in patent application 317885, and to methods for the preparation thereof.
U.S. Patent 3,296,255, discloses certain inter-mediates of 2~-cyano-3-oxos~eroids as follows:
Example 16(a~ 17~-acetoxy-4a,5a-epoxyandostano[2,3-d]isox-a~ole Example 17~a~ 4a,5a-epoxy-17~ hy~roxy-17a-ethynylandrostano-[2,3-d]isoxazole Example 18(a) 4~,5a-epoxy-17B-hydroxy-17a-methylandrostano-[2,3-d]isoxazole 20Example 34 6a,17a-dimethyl-17~-hydroxy-4-androstano[2,3-d]~isoxa ole Example 55 4-methyl-17~hydroxy-4-androstano[2,3-dJisox-azole Example 56 4,17a-dimethyl-17~-hydroxy-4-androsteno[2,3-d~isoxazole~
The compounds according to the invention have the formula CH~¦

D R' "
: ~ ... III
: R is hydrogen or methyl;
R' is hydroxy;
R" is hydrogen, lower-alkyl, lower-alkenyl or , .. : .: . : "
: : -- :

, , lower-alkynyl; or R' and R" together represent oxo or ethylenedioxy;
R "' is hydrogen or methylO
According to the invention, a compound of For~ula III is prepared from a compound of the formula ~' ''' ...II
wherein *, Rl r R" and Rll' have ~he meanings given above by epoxidizing the 4~5-double bond with hydrogen peroxide or a peracid.
As peracid, one may use m-chloroperbenzoic acid, p-nitroper~enzoic acid, peracetic acid, perbenzoic acid, permaleic acid, perphthalic acid.
~ When R" in the compounds of Formulas II or III i~
lower-alkyl, lower-al~ynyl or lower-alkenyl, the groups can possess from one to ~hree carbon atoms, thus including such groups as methyl, ethyl, propyl, isopropyl, ethynyl, 1-propynyl, 2-propynyl, vinyl, allyl and l-propenyl.
Endocrinological evalua~ion of certain species o$
the intermediates of Formulas II and III has shown ~hat khey are useful in disrupting pregnancy in female mammals upon oral administration subsequent to conception. Inter-ceptive activity was evaluated in Sprague-Dawley female rats as follows: vaginal smears were taken and read for the presence of spermatozoa following overnight mating~ The 2S day spermatozoa were found was designated as day one of pregnancy. The test compound was administered orally in a single dose on day ten of pregnancy at varying dose levels in different groups of rats. On the fif~th ~ay after in~emination, the rats were killed with an overdose of sodium , , , .-, .. . .
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pentobarbital and the uterine implantation sites were counted. Each implantation site was assessed as being a de~eloping fetus, a dead fetus or a resorption site. The minimum effective dose in 100% of the animals ~MEDloo) was then determined.
The following examples will further illustrate the - invention.
Example 1 a~ 17~-Hydroxy-17-methyl-4-(phenylthiomethyl)androst-4-en-_ 3-on A mixture of 904 g. (3 m.) of 17~-hydroxy-17-methyl-androst-4~en-3-one, 650 ml. (6.3 m.~ of thiophenol, 560 ml. of 38% formaldehyde, 680 ml. of triethylamine and 1.7 1. of absolute alcohol was heate~ at reflux for 55 hours and then cooled to room temperature. The light brown solution was quenched in 16 1. of 0.5N aqueous potassi~n hydr~xide and stirred for 20 minutes until a uniformly dispersed suspension had been formed. The product was collected by filtration using coarse filter paper and the filter ~ake was washed with 5 x 1.5 1. water. The solid was slurried in 4 1. of water, separated on a funnel and washed again thoroughly with water until the fil~rate was neutral~ In or~er to reduce the odor of thiophenol the filter cake was washed 5 times with 100 ml. of n-hexane and then it was dried at 40C. ln vacuo. Recrystallization of the crude material from 6.5 1. of absolute alcohol, washing with alcohol and drying at 30-50C. in vacuo yielded three crops of product, 762 g. tm.p. 133-138C.), 141 g.
(m.p. 121-128C.) and 41 g. (m.p. 123-130C.~. The purity of the second and third crops was identical with that of the first crop by TLC analysi.s. Therefox~, all crops were combined for a to~al yield of 979 g. (75~) of 17B-hydroxy-17-methyl-4-(phenylthiomethyl)androst-4-en-3-one.
b~ ~
Into a 22 1. 3-necked flask equipped with an efficient stirrer, nitrogen inlet tube, dropping funnel and a condenser was placed 1.8 1. of Raney nickel-water ~ludge (W. Grace Co., No. 42000). A slow strearn of nitrogen was : ' ' .

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applied and the catalyst was washed thoroughly with 3 X 4 1.
of water followed by 4 x 4 1. of acetone. After the last acetone wash, the catalyst ~as suspended in 9 1. of fresh acetone and a warm solution (about 40C.) of 520 g. of 17~-hydroxy~17-methyl-4-(phenylthiomethyl~androst~4-en-3-ons in 3 1. of acetone was added from a dropping unnel with good stirring over a 10 minute period. The tempera~ure was brought to reflux cautiously and gentle refluxing was con-tinued for 5 hour~. Stirriny with no heat was maintained overnight and then the Raney nickel was allowed to ~tle for about 2 hours. The supernatant liquid was removed by suction and the catalyst was washed 4 ~imes with 4 1~ of acetone. The combined main portion and the washes were filtered through a filter aid and concentrated to a total volume of about 1 liter. The resulting thick slurry was cooled, filtered and the filter cake was washed with 2 x 50 ml. of cold acetone and then with 3 x 200 ml. of n-hexane. After drying the product at 60~C. in vacuo it weighed 316 g. and melted at 141-144C., an 82~ yield of 2C 17~-hydroxy-4,17-dimethylandrost-4-en-3-one.
c) 17~-~ydroxy-2~-hydroxymethylene-4,17-dimethylandrost-4-en-3-one __ __ _ _ A clear solution of 620 g. ~1.95 mO) of 17~-hydroxy 4,17~dimethylandroæt--4-en-3-one in 5O5 lo of dry tetrahydrofuran and 12 ml. of methanol was stirred at room temperature under nitrogen and 220 g. (5 m.) ~f sodlum methoxide wa~ added all at once. As soon a~ a uniform suspension had been fo~ned, 610 ml. (10 m.) o me~hyl for~
mate was intr~duced from a dropping funnel over a period 30 of 1.5 hours~ The temperature was maintained at 20-25C.
by intermittent cooling. Stirrin~ was then continued or an additional 20 hour3. The reddish brown mixture was diluted with 720 ml. of distilled water and concentrated in vacuo to about 2O5 1. volume. The re~idue wa~ dissolved in 4.5 1. of water, charcoaled, filtered through a layer of filter aid and placed in a 12 1. battery jar ~urrounded ,f~5~7~3 ~ 5~
by an ice bath. The mixture was cooled to 8C. and 800 mlO
of 6N HCl was added dropwise with efficient stirring until the pH was lowered to about 3. The acidification was completed in 2.5 hours, the resultiny thlck su~pen~ion was stixred at 5C. for an additional 1.5 hours and then it was filtered. Thorough washing with water (4 x 100 ml~) and drying at 60C. in vacuo yielded 641 y. (9~%) of 17 hydroxy-2-hydroxymethylene-4,17- dimethylandr~st-4-en-3-one as a light yellow product, m.p. 182-188C.
d) ~ -17~-ol [II; R and R" are CH , R' is OH, R''' is H]

A mixture of 746 g. (2.17 m.) of 17~-hydroxy-2-hydroxy-methylene-4,17-dimethylandrost-4~en-3-one and 6.5 1. of glacial acetic acid was stirred vig~rously a~d a solution containing 165 g. (2.4 m.) of hydroxylamine hydrochloride and 335 g. (2.46 m.) of sodium acetate tri-hydrate in 1 1. of water was added all at once. Stirring at room temperature was continued for a period of 6 houxs.
A total of 4OS 1. of water was added over a period o~ about 15 minutes to the resulting suspension, the mixture wa~
stirred ~or an additional 15 minutes and the ~olid material was filtered ~ff. The solid was washed with wa~-er t4 x 250 ml.) and n-hexane (1 x 250 ml.) and dried at 50C. ln vacuo overnight to yield 695 g. Gf crude product melting at 170-178Co The entire batch was recrystallized by dissolving it in 7 lo of absolute alcohol and 250 ml~ of methanol a~d then by chilling to 5C. A second crop was obtained from approximately 3.5 1. of volume. The filter were washed with cold alcohol followed by n-hexane and dried at 50C. in vacuo to give 430 gO of first crop material, m p. 189-192C. and 107 g. of second crop material, m.p. 189-192C. The mother liquor wa~ con-centrated in vacuo and two more crops were isolated: 66 g., m.p. 183-185C. and 41 g., m.p. 167-177Co They were r~crystallized from 700 ml. of alcohol, and the white pro-duct wa slurried in 150 ml. o~ isopropyl acetate, filtered and dried at 50C. in vacuo to give an additional 64 g.

, 'f~7~
~ 6--of good material, m.p. 190-194~C. which waq combined with the first two crops for a total of 607 g. (82%~ of 4,17-dimethylandro~a-2,4-dieno[2,3-d]isoxazol-17~-ol e) 17~-ol [III; R and R" are CH3, R' is OH, R'''is H]
537 gO (1.57 m.) of 4,17-dimethylandrosta-2,4-dieno-[2,3-d]isoxazol-17B-ol was dissolved in 4 1. of methylene dichloride and the solution was decolorized with charcoal. The filtrate was placed in a 22 1. 3-necked - 10 flask, diluted with an additional 3 1. of methylene dichlo-ride and cooled to 3C. Over a period of 40 minutes 375 g (1.75 m.) of 80% m~chloroperbenzoic acid was added por~ion-wise with efficient stirring while the temperature was maintained below 5C. The mixture was stirred in an ice bath for 6 hours and then overnight at room temperature.
The mixture was cooled to 5C. and ths ~xcess m~chloro-perbenæoic acid was decomposed by adding aqueous sodium sulfite solution t50 g. of Na2S03 in 2 1. of water~. The two phase mixture was stirred for five minutes, filtered 20 in order ~o remove the solid m-chloroben~oic acid, and the filter cake was washed with 500 ml. of methylene dichlorlde.
The combined filtrates were treated with sodium bicarbonate solution until neutral. The organic layer wa~ washed with 2 1. of water followed by 2 1. of brine. The combined 25 aqueous layers were reextracted once with 1 1. of methylene dichloride and the extract wa~ combined with the main organic por tion . The solution was dried over anhydrous sodium sulfate, decolorized with charcoal, concentrated to a total volume of 3 1. and cooled to 10C. The product was 30 filtered, washed with cold isopropyl alcohol (2 x 50 mlO ) and n-hexane (3 x 100 ml.), and then it was dried at 60C.
in vacuo to give 331 g. (crop A~, m.pO 221-224CC.
From the f iltrate three additional crops were isolated by concentration and cooling:
B. 98 g., m.p. 215-217C.
C. 16 gO, m.p. 187-192C.
D. 15 g., m.p. 185-192C.

' ,, - - . -:: :
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Crop B was crystallized from 330 ml. of dimethylformamide to yield 94 g. of good material, m.p. 235-239C (crop E).
Crops C and D were added to the filtrate and the mixture was heated until a clear solution resulted. By cooling the solution an additional 23 g. of the product (m.p.
225-233Co) was recovered and c~mbined withcrops A and E
for a total yield of ~48 g. (80%) of 4~,5~ epoxy-4,17-dimethylandrost-2-eno[2,3-d]isoxazol-17~-ol. A sample of the compound when recrystallized from a te~rahydxofuran-e~hanol mixture was obtained in the form of colorlessmatted needles, m.p. 244-252C.; [a]25 = +67.7 (1% in chloroform) Example 2 a) ~
15 3-one was prepared from 32.28 g. of 17~-hydroxy~4-methyl- -androst-4-en=3-one and 32 ml. of methyl formate by a pro-cedur~ anal~gou~ to that of Example 1, part (c) except that sodium hydride (15 g., 50%) was used in place of sodium methoxide. The 20 gO of product obtained was used directly in the next reaction, b) ~ [II;
R i~ CH3, R' i8 OH, R" and R''' are H] was prepared from 20 g. of 2-hydroxymethylene-17~-hydroxy-4-methylandrost-4-en-3-one, 4.3 g. of hydroxylamine hydro~hloride and 5 g.
o~ so~ium acetate in ethanol according to the procedur~
of Example 1, part (d), and obtained in 73% yield, mOp.
176-179C. when recrystalliæed from ethyl acetate~
c) ~
~III; R is CH3, R' is OH, R" and R''' are H] was prepared from 32.75 g. of 4-methylandrosta-2,4-dieno[2,3-d]is~xaz~l-17~-ol and 21 g. of 85% m-chloroperbenzoic acid in 500 ml.
of methylene dichloride according to the procedure of Example 1, part (e), and there was obtained 13.91 gO of product, m.p. 220-226~C., recrystallized from an ethyl acetate-ethanol mixture; [a]DS = +92.5 (1% in chloroform).
4a,5a-Expoxy-4-methylandrost-2-eno~2,3-d]isoxazol-17~-ol was found to have MEDloo = 500 mg/kg when te~ted in ..~

.

1L 3~ /5Z~7 --8~-rats for in~ercept.ive activlty by oral administration at day 10 of pregnancy.

a) 4-Methylandrosta-2,4-dieno[2,3-d]isoxazol-17-one ~II;
S R is CH3, R' and R" together are 0, R''' is H]
To a stirred suspension of 52.0 g. of pyridtnlu~
chlorochromate in 1000 ml. of mathylene dichloride was added a solution of 61.2 g. of 4~methylandrosta-2,~-dieno [2,3-d]isoxazol-17~-ol (Example 3b) in 1000 ml. of methylene dichloride. The reaction mixture was ~tirred for thxee hours at room temperature, an addi~ional 25.0 g. of pyridinium chlorochromate then added, and the mixture stirred for about 16 hours longer. The resul ing 5u8pension wa~
filtered through an alumina pad, and the filtrate wa~
washed with 2N hydrochoric acid, water and dilute a~UeOU9 sodium bicarbonate. The organic layer wa~ dried over ~n-hydrous magneYium sulfat2, filtered and the filtrate con-centrated until cry~talline material s~paratad~ ~he pro-duct was obtained in four crops totaling 51.2 g. The 2Q frac~ions with the least amount of polar impuriti~, a~
determined by thin layer chromatography, were recryst~lllzed from acetic acid to give 11.9 g. o 4~methylandro~t~-2,4-dieno[2,3-d]i~oxazol-17-one, pale yellow powder, m.pO
236-238C.
b) 4a 5~ oxY-4-methYlandrost-2-eno[2 3-d]i~oxazol-17-~ne [III; R is CH3, R' and R" together are 0, R "' is H~ wa~
prepared from 17.35 g. of 4-methylandrosta-2,4-di~no[2,3-dl isoxazol-17-one and 12.5 g. of m-chloroperbenzoic acid ~n 500 ml. of m~thylene dichloride according to ~he procedurQ
of Example 1, part (e), and there waY obtained 7 gO of product, m.p. 249-251C.; [~]25 = +135 (1~ in chloroform).
4a,5~-Epoxy-4-methylandro~t-2-eno[2,3-d]i~OXaZsl-17-one when administered orally to rats at day ten of pregnancy was partially effective as an interceptive ag~nt at a single dose of 500 mg/kg.

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.
a) [2,3-d- soxazole [II; R is CH3l R' and R" together are -OCH2CH2O-, R" ' is H]
A mixture of 39.2 g. of 4-methylandrosta-2,4-dieno[2,3-d]isoxazol-17 one (Example 4, part a~, 150 ml.
of ethylene glycol and 1.5 g. of p-toluenesulfonic acid in 800 mlO of benzene was heated at reflux under a water separator for about 24 hours. The reaction mixture was concentrated to remove ~he solvent, and the residue was taken up in a mixture of ether and methylene dichloride and washed with dilute sodium hydroxide solution. The organic layer was dried over anhydrous magnesium sulfate, filtered and concentrated to drynes~. The residue was crystallized from ethanol containing a few drops of pyridine to give 30.16 g. of 4-methyl-17,17-(1,2 ethylenedioxy) androsta-2,4~dienoE2,3-d]isoxazole, m.p. 173-175C.
b~
2-eno-[2,3-d]isoxazole [III: R is CH3, Rl and R" together ____ are -OCH2CH2O-, R''' is H] was prepared fxom 28~82 g. of 4-methyl-17,17-(1,2-ethylenedioxy)androsta-2,4-dieno[2,3-d]
isoxazole and 16.3 g. of m-chloroperbenzoic acid in 500 ml.
of methylene dichloride containing 1 ml. of pyridine, according to the procedure of Example 1, part (~), and there was obtained 25.9Q g. of product, m.p. 205~211C~

a) 2-Hydroxymethylene ~ a-~regn-4-en 20-yn-3-one was preparPd from 65.9 g. of 17-hydroxy-4-methyl-17~-pregn-4-en-20-yn-3-one [m.p. 198 202C~; [a]D
~60.2 (1% in chloroorm)] and 64 ml. of methyl formate by a procedure analogous to that of Example 1, part (c~ except that sodium hydride (19.6 g.) was us~d ln place of sodium methoxide. A crude yield of over 90% was obtain~dO
b) ~II; R is CH3, R' is OH, R" is C_CH, R' " is H] was prepAred from 3.5. g. of 2-hydroxymethylene-17-hydroxy-4-methyl-17~-pregn-4-en-20-yn-3-one, 0.75 g. of hydroxylamine hydro-, 7~
~10~chloridP, 1.3 gO of sodi~n a~etate and 50 ml of 80~ acetic acid, heated one hour a~ 100C~ There was ob~ained 1.5 g.
of product, pale yellow crystal~, m p. 238-243C. when recrystallized from an ethanol-methylene dichloride mixture, [~]D = ~0.19 (1% in chloroform).
c) ~= ~=~
isoxazol-17-ol [III; R is CH , R' is OH, R" is C-CH, R''' is H] was prepared from 41~7 g. of 4-methyl-17~-pregna-2, 4-dien-20-yno[2,3 d]isoxazol-17-ol and 21~6 g. of m-chloro-perbenzoic acid in 1000 ml. of methylenP dichlorideaccording ~o the procedure of Example 1 , par~ (e), and there was obtained about 35 g. of product, crystallized from a methylene dichl~ride-ethyl acetate mix~ure, A sample crystallized from an ethyl acetate-methanol mixture had m.p. 245-247C.

a)

3-one was prepared from 286 gO of 17~-hydroxy-6~-methyl-. .
androst-4-en-3-one (6a methyltestosterone), 410 ml~ of methyl formate, 140 g. of sodium methoxidet 40 ml. of methanol and 3 1. of tetrahydrofuran according to the pro-cedure of Example 1, part (c~. The total product, obtained nearly quantitative yield as an amber glass was used directly in the next reaction.
b) 6a-Meth landrosta-2,4 - dieno[2,3-d]isoxazol-17~-ol [II; R and R' are H, R" is O~, R' " is a-CH3] was prepared from 312 g. of 17~-hydr~xy-2~hydroxymethylene-6~-methyl-androst-4-en-3-ona, 75 g~ of hydroxylamine hydrochloride, 135 g. of sodium acetate trihydrate and 3 1. of glacial acetic acid aacording to the procedure of Example 1, part (d), and there was obtained 181 g. of product, m.p. 180-183C. when crystallized fr~m isopropyl alcohol. A sample when recrystallized from isopropyl acetate had ~he m.p.
188-190C.
c) ~III; R and R' are H, R" is OH, Rt'' is ~-C~13] was prepared from 181 g. of 6~-methylandrosta-2,4 - dieno[2,3-d]isQxazol-i . .
`. ' , ~ ' ' , - ' , .

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17~-ol and 128 g. of m-chloroperbenzoic acld in 2.5 1. of methylene dichloride according to the procedure of ~xample 1, part (e), and there was obtained 127 g~ of product, m.p. 212-214C, when slurried with isopropyl acetate. A
S sample when recrys~allized from ethyl acetate had the m.p. 220-222C.

4~,5~-Epoxy-6a-methylandrost-2-eno[2,3-d]
isoxazol-17~-ol when administered orally to rats at day ten of pregnancy showed activity as an interceptive agent at a single dose of 500 mg/kg.
~.
a) ~ d en-3-one was prepared from 28.1 y. of 17~hydroxy-4,6~-dimethylandrost-4-en-3-one [Burn et al., Tetrahedron 19, 1762 (1963)], 24.9 g. of methyl formate and 11.4 g. of sodium me~hoxide according to the procedure of Example 1, part (c), and there was obtained 24.8 g. of solid product u~ed directly in the next reaction.
b) [II; R is C~3, R' is OH, R" is H, R" ' i ~-CH3] was pre-pared from 20.8 g. of 17~-hydroxy-2 hydroxymethylene-4,6~-dimethylandrost- -4~-~n - 3---one, 4~4 g. o hydro~, xylamine hydrochloride, 8.2 g. of sodium acPtate trihydrate and 250 ml. of acetic acid according to the procedure of Example 1, part (d), and there was obtAined 19.9 g. o~
product as a colorless solid.
c) 4~ Sa - Enox -4 6~-dimeth landrost-2-eno[2,3-d]isoxazQl-~L ~
1?~-1 [III; R is CH3, R' is OH, R" is H, R''' is ~-C~3]
was prepared from 23.2 g. of 4,6~-dimethylandrosta-2,4-dieno[2,3-d]is~xazol-17~-ol and 15.~ g. ~f m-chloroperbenzoic acid in 320 ml. of methylene dichloride according to the procedure ~f Example 1, part (e). The crude prod~ct was chromatographed by Water's LC#500 high pressure liquid chromatography procedure and eluted with n-hexane containing increasing amounts of ethyl acetate to give 17.4 g. of epoxidized product, used directly in the next reaction.
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Claims (4)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for preparing a compound of the Formula III

. . . III
wherein R is hydrogen or methyl;
R' is hydroxy;
R" is hydrogen, lower-alkyl, lower-alkenyl or lower-alkynyl; or R' and R" together represent oxo or ethyl-enedioxy; and R''' is hydrogen or methyl;
with the proviso that when R is hydrogen, R''' is .alpha.-methyl;
and when R is methyl, R''' is hydrogen ox .beta.-methyl, charac-terized by epoxidizing the double bond of a corresponding compound of Formula II

...II

with hydrogen peroxide or a peracid.

2. A process according to claim 1, for preparing 4.alpha.,5.alpha.-epoxy-4,17-dimethylandrost-2-eno[2,3-d]isoxazol-17.beta.-o1 which comprises reacting 4,17-dimethylandrosta-2,4-dieno-[2,3-d]isoxazol-17.beta.-o1 with m-chloroperbenzoic acid.

3. A compound of the Formula III as defined in claim 1, when prepared by the process according to claim 1, or by an obvious chemical equivalent thereof.

4. 4.alpha.,5.beta.-Epoxy-4,17-dimethylandrost-2-eno[2,3-d]-isoxazol-17.beta.-o1 when prepared by the process of claim 2, or by an obvious chemical equivalent thereof.