4-SUBSTITUTED 6- ALKYLIDENANDROSTENE-3,17-DIONE DERIVATIVES AND PROCESS FOR THEIR PREPARATION

Abstract: The invention relates to 4-substituted 6-alkylidenandrostene-3,17-dione derivatives of the following formula wherein each of R₁, R₂ and R₃ is, independently, hydrogen or C₁-C₆ alkyl; R₄ is hydrogen or fluorine; (x) represents a single or double bond; and R is, especially, a hydroxy or mercapto or amino group or a functional derivative thereof. The compounds of the invention show aromatase inhibitory activity and may be useful, for instance, in the treatment of hormone-dependent tumors and of prostatic hyperplasia

Description: The present invention relates to 4-substituted 6-alkylidenandrostene-3,17-dione derivatives, to a process for their preparation, to pharmaceutical compositions containing them, and to the use of said compounds for the treatment of hormone-dependent cancers. Basic and clinical data indicate that aromatized metabolites of androgens, i.e. the estrogens, are the hormones involved in the pathogenic cellular changes associated with the growth of some hormone-dependent cancers, such as, e.g., breast, endometrial, ovarian and pancreatic carcinomas. Estrogens are also involved in the pathogenesis of benign prostatic hyperplasia. Endogenous estrogens are ultimately formed from either androstenedione or testosterone as immediate precursors. The reaction of central importance is the aromatization of the steroidic ring A, which is performed by the enzyme aromatase. As aromatization is a unique reaction and the last in the series of steps in the biosynthesis of estrogens, it has been envisaged that an effective inhibition of the aromatase, resulting from compounds able to interact with the aromatizing steps, may have useful application for controling the amount of circulating estrogens, estrogen-dependent processes in reproduction, and estrogen-dependent tumours. Known steroidal substances which have been reported to be endowed with an aromatase-inhibiting action are, for example, testololactone [U.S. Pat. 2,744,120], 4-hydroxy androst-4-ene-3,17-dione and esters thereof [see, for example, U.S. Pat. 4,235,893], 10-(1,2-propadienyl) estr-4-ene-3,17-dione [U.S. Pat. 4,289,762], 10-(2-propynyl )estr-4-ene-3,17-dione [J. Am. Chem. Soc., 103 , 3221 (1981) and U.S. Pat. 4,322,416], 19-thioandrostene derivatives [Europ.Pat. Appl. 100566], androsta-4,6-diene-3,17-dione, androsta-1,4,6-triene-3,17-dione [G.B. Pat. Appl. 2,100,601A] and androsta-1,4-diene-3,17-dione [Cancer Res. (Suppl.) 42 , 3327 (1982)]. The novel compounds of the present invention are potent aromatase inhibitors, by virtue of their ability to specifically inhibit estrogens synthesis. The present invention provides compounds having the following general formula (I) wherein each of R₁, R₂ and R₃, independently, is hydrogen or C₁-C₆ alkyl; R₄ is hydrogen or fluorine; the symbol ---- indicates that (x) may be either a single bond or a double bond; R is 1) a group -OR₅ wherein R₅ is a) hydrogen; b) C₁-C₆ alkyl; c) a phenyl or benzyl group, each unsubstituted or ring-substituted by one or more substituents chosen from C₁-C₄ alkyl, halogen, trifluoromethyl, nitro, amino, hydroxy and C₁-C₄ alkoxy; d) a group - COR₆ wherein R₆ is (i) a C₁-C₂₂ saturated or C₂-C₂₂ unsaturated aliphatic hydrocarbon radical; (ii) a C₄-C₇ monocycloalkyl group; or (iii) a phenyl or benzyl group, each unsubstituted or ring substituted as reported above; or e) a hydroxy protecting group; 2) a group - SR₇ wherein R₇ either has one of the meanings (a) to (d) indicated above for R₅ or is a group -SR₈ wherein R₈ is (iv) C₁-C₆ alkyl; (v) a phenyl or benzyl group, each unsubstituted or ring-substituted as reported above; or (vi) a steroidic residue of formula wherein R₁, R₂, R₃, R₄ and (x) are as defined above; 3) the group -N₃; or 4) a group wherein each of R₉ and R₁₀, independently , is hydrogen or C₁-C₆ alkyl. The invention includes also the pharmaceutically acceptable salts of the compounds of formula (I) containing a salifiable group. In the formulae of this specification, a heavy solid line () indicates that a substituent is in the β-configuration, i.e. above the plane of the ring, and a wavy line () indicates that a substituent, such as, e.g., R₃ or R₄, may be either in the α-configuration, i.e. below the plane of the ring, or in the β-configuration or in both, i.e. a mixture thereof such as a racemic mixture. Also the 1-substituent R₁ may be, when (x) is a single bond, either in the α-configuration or in the β-configuration or in both, i.e. a mixture thereof such as a racemic mixture. The formula reported above for the compounds of the invention is meant to comprise all the possible isomers of formula (I) both separately and in mixture, including also the Z and E isomers of the compounds of formula (I) in which R₂ is C₁-C₆ alkyl, both separately and in mixture. The aliphatic hydrocarbon radicals, including the alkyl groups and the aliphatic moieties of the alkoxy groups, may be branched or straight chain. A C₁-C₆ or C₁-C₄ alkyl group is, preferably, methyl or ethyl. A halogen is, preferably, chlorine, bromine or fluorine, in particular fluorine. A C₁-C₄ alkoxy group is, preferably, methoxy or ethoxy. A C₁-C₂₂ saturated aliphatic hydrocarbon radical is, preferably, a C₁-C₁₇ alkyl group, in particular, e.g., methyl, ethyl, n-propyl, n-butyl, tert-butyl or the residue of a saturated fatty acid, e.g. n-undecyl, n-tridecyl, n-pentadecyl or n-heptadecyl. A C₂-C₂₂ unsaturated aliphatic hydrocarbon radical preferably contains 2 to 17 carbon atoms and may be, e.g., allyl, or the residue of an unsaturated fatty acid, e.g., cis - or trans-8-heptadecenyl. A C₄-C₇ monocycloalkyl group is, preferably, a C₅-C₇ monocycloalkyl, in particular cyclopentyl or cyclohexyl A hydroxy protecting group is a group, especially an ether residue, which can be removed under mild reaction conditions, e.g. acid hydrolysis. Examples are residues of acetalic ethers, enolethers and silylethers. The preferred groups are: wherein W is -O- or -CH₂-, and Alk is a lower alkyl group; more preferably, they are 2′-tetrahydropyranyl or trimethylsylyl. When R is a group -OR₅ or a group -SR₇ wherein R₅ or, respectively, R₇ is -COR₆, preferably R₆ is a C₁-C₂₂ saturated aliphatic hydrocarbon radical, especially a C₁-C₁₇ alkyl group and, in particular, one of those specified before, most preferably methyl or ethyl; or a phenyl or benzyl group either unsubstituted or ring-substituted by C₁-C₄ alkyl, in particular methyl, or by a fluorine, trifluoromethyl, nitro, hydroxy, methoxy or ethoxy group. When R is a group -OR₅ or a group -SR₇, preferably R₅ or, respectively, R₇ is hydrogen; C₁-C₆ alkyl, in particular methyl or ethyl; or a group -COR₆ wherein R₆ is C₁ - C₁₇ alkyl, in particular methyl or ethyl. When R is a group preferably each R₉ and R₁₀ is, independently, hydrogen or C₁-C₃ alkyl;preferred groups are amino, methylamino, ethylamino, dimethylamino and diethylamino; most preferably amino. As already said, the invention includes also the pharmaceutically acceptable salts of the compounds of formula (I). Salts according to the invention are the salts of the compounds of formula (I) with pharmaceutically acceptable acids, both inorganic acids such as, e.g., hydrochloric, sulfuric or phosphoric acid, and organic acids such as, e.g., citric, fumaric, maleic, malic, ascorbic, tartaric, benzoic, acetic, p henylacetic,cyclohexylacetic, 3-cyclohexylpropionic, methanesulfonic, ethanesulfonic, benzenesulfonic,p-toluenesulfonic or p-nitrobenzenesulfonic acid. Also the quaternary ammonium salts and hydroxides of the compounds of formula (I) wherein R is are within the scope of the invention: they are, for instance, quaternary alkyl, e.g., methyl, ethyl or cetyl, ammonium salts, e.g. iodides, bromides or chlorides, or hydroxides. A preferred class of compounds according to the invention are the compounds of formula (I) wherein each of R₁, R₂ and R₃, independently, is hydrogen or C₁-C₆ alkyl; R₄ is hydrogen or fluorine; (x) represents a single bond or a double bond; and R is a group -OR₅ or a group -SR₇ wherein R₅ or, respectively, R₇ is hydrogen, C₁-C₆ alkyl or a group -COR₆ wherein R₆ is C₁-C₁₇ alkyl. In the above preferred class preferably R₁ is hydrogen or methyl; R₂ is hydrogen; R₃ is hydrogen, methyl or ethyl; and R₄ is hydrogen or fluorine; preferred values for R₅ and, respectively, R₇ are hydrogen, methyl, and ethyl ; and preferred values for R₆ are methyl, ethyl, n-propyl, n-butyl and a residue of a saturated fatty acid, e.g., n-undecyl , n-tridecyl, n-pentadecyl or n-heptadecyl. When R₁ is a C₁-C₆ alkyl group, preferably (x) represents a double bond. Example of specific compounds of the above preferred class are: 4-hydroxy-6-methylenandrost-4-ene-3,17-dione; 4-hydroxy-6- ethylene-7α- methylandrost-4-ene-3,17-dione 4-hydroxy-6-methylene-16α-fluoroandr st-4-ene-3,17-dione; 4-hydroxy-6-methylene-16β-fluo roandrost-4-ene-3,17-dione; 4-hydroxy-6-methylene-7α-methyl-16α-flu roandrost-4-ene-3,17-dione; 4-hydroxy-6-methylene-7 α-methyl-16β-fluoroandrost-4-ene-3,17-dione; 4-methoxy-6-methylenan rost-4-ene-3,17-dione; 4-methoxy-6-methylene-7α-met hylandrost -4- ene-3,17-dione; 4-methoxy-6-methylene-16α-fluoroandrost-4-ene-3,17- ione; 4-methoxy-6-methylene-16β-fluoroandrost-4-ene -3,17-dione; 4-methoxy-6-methylene-7α-methyl-16α-fluoroandrost-4-en -3,17-dione; 4-methoxy-6-methylene-7α-methyl-16β-fluoroandrost-4-ene-3,17-dione 4-acetoxy-6-methylenandrost-4-ene-3,17-dione; 4-acetoxy-6-methylene-7α-methylandrost -4- ene-3,17-dione; 4-acetoxy-6-methylene-16α-fluoroandrost-4-ene-3,17- ione; 4-acetoxy-6-methylene-16β-fluoroandrost-4-ene -3,17-dione; 4-acetoxy-6-methylene-7α-methyl-16α-fluoroandrost-4-en -3,17-dione; 4-acetoxy-6-methylene-7α-methyl-16β-fl uoroandrost-4-ene-3,17-dione; 4-hydroxy-6-methylenandrosta-1,4-dien -3,17-dione; 4-hydroxy-6-methylene-7α-methylandrost a-1,4-diene-3,17-dione; 4-hydroxy-6-methylene-16α-fluoroandrosta-1, -diene-3,17-dione; 4-hydroxy-6-methylene-16β-fluoro androsta-1,4-diene-3,17-dione; 4-hydroxy-6-methylene-7α-methyl-16α- luoroandrosta-1,4-diene-3,17-dione; 4-hydroxy-6-met hylene-7α-methyl-16β-fluoroandrosta-1,4-diene-3,17-dione; 4-methoxy 6-methylenandrosta-1,4-diene-3,17-dione; 4-methoxy- 6-methylene-7α-methylandrosta-1,4-diene-3,17-dione; 4-methoxy-6-met ylene-16α-fluoroandrosta-1,4-diene-3,17-dione; 4-me thoxy-6-methylene-16β-fluoroandrosta-1,4-diene-3,17-dione; 4-methox -6-methylene-7α-methyl-16α-fluoroandrosta-1,4-diene-3,1 7-dione; 4- methoxy-6-methylene-7α- methyl-16β- fluoroandrosta-1,4-diene-3,17-dione; 4-acetoxy-6-methylenandrosta-1,4-diene-3,17-dione; 4-acetoxy- -methylene-7α-methylandrosta-1,4-diene-3,17-dione; 4-acetoxy-6-methylene-16α-fluoroandrosta-1,4-diene-3,17-dione; 4-ac toxy-6-methylene-16β-fluoroandrosta-1,4-diene-3,17-dion e; 4-acetoxy-6-methylene-7α-methyl-16α-fluoroandrosta-1,4 -diene-3,17-dione; 4-acetoxy-6-methylene-7α-methyl-16β-fluoroandros a-1,4-diene-3,17-dione; 1-methyl-4-hydroxy-6-methyl enandrosta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-hydroxy-6-methylen ndrosta-1,4-diene-3,17-dione; 1-methyl-4-hydroxy-6- methylene-16α-fluoroandrosta-1,4-diene-3,17-dione; 1-methyl-4-hydro y-6-methylene-16β-fluoroandrosta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-hydroxy-6-methylene-16α-fluoroandrosta-1,4-diene-3, 7-dione; 1,7α-dimethyl-4-hydroxy-6-methylene-16β-fl uoroandrosta-1,4-diene-3,17-dione; 1-methyl-4-methoxy-6-metylenandr sta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-methoxy-6 -methylenandrosta-1,4-diene-3,17-dione; 1-methyl-4-methoxy-6-methylene-16α-fluoroandrosta-1,4-diene-3,17- ione; 1-methyl-4-methoxy-6-methylene-16β-fluoroandr osta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-methoxy-6-methylene-16α- luoroandrosta-1,4-diene-3,17-dione; 1,7α-dimethyl-4 -methoxy-6-methylene-16β-fluoroandrosta-1,4-diene-3,17-dione; 1-met yl-4-acetoxy-6-methylenandrosta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-acetoxy-6-methylenandrosta-1,4-diene-3,17-dione; 1-methyl-4-acetoxy-6-methylene-16α-fluoroandrosta-1,4-d iene-3,17-dione; 1-methyl-4-acetoxy-6-methylene-16β-fluoroandrosta- ,4-diene-3,17-dione; 1,7α-dimethyl-4-acetoxy-6-meth ylene-16α-fluoroandrosta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-acet xy-6-methylene-16β-fluoroandrosta-1,4-diene-3,17-dione; 4-mercapto-6-methylenandrost-4-ene-3,17-dione; 4-mercapto-6-me hylene-7α-methylandrost-4-ene-3,17-dione; 4-mercapt o-6-methylene-16α-fluoroandrost-4-ene-3,17-dione; 4-mercapto-6-meth lene-16β-fluoroandrost-4-ene-3,17-dione; 4-mercapto -6-methylene-7α-methyl-16α-fluoroandrost-4-ene-3,17-dione; 4-mercapto-6-methylene-7α-methyl-16β-fluoroandrost-4-ene-3,17-dio e; 4-acetylthio-6-methylenandrost-4-ene-3,17-dione; 4-acetylthio-6-methylene-7α-methylandrost-4-ene-3,17-dione; 4- cetylthio-6-methylene-16αfluoroandrost-4-ene-3,17-dione ; 4-acetylthio-6-methylene-16β-fluoroandrost-4-ene-3,17-dione; -acetylthio-6-methylene-7α-methyl-16αfluoroandrost-4-en e-3,17-dione; 4-acetylthio-6-methylene-7α-methyl-16β-fluoroandrost- -ene-3,17-dione; 4-ethylthio-6-methylenandrost-4-en e-3,17-dione; 4-ethylthio-6-methylene-7α-methylandrost-4-ene-3,17-d one; 4-ethylthio-6-methylene-16α-fluoroandrost-4-en e-3,17-dione; 4-ethylthio-6-methylene-16β-fluoroandrost-4-ene,3,17- ione; 4-ethylthio-6-methylene-7α-methyl-16β-fluoroa ndrost-4-ene-3,17-dione; 4-ethylthio-6-methylene-7α-methyl-16β-fluo oandrost-4-ene-3,17-dione; 4-mercapto-6-methylenand rosta-1,4-diene-3,17-dione; 4-mercapto-6-methylene-7α-methylandrost -1,4-diene-3,17-dione; 4-mercapto-7-methylene-16α-f luoroandrosta-1,4-diene-3,17-dione; 4-mercapto-6-methylene-16β-fluo oandrosta-1,4-diene-3,17-dione; 4-mercapto-6-methylene-7α-methyl-16α-fluoroandrosta-1,4-diene-3,1 -dione; 4-mercapto-6-methylene-7α-methyl-16β-fluoro androsta-1,4-diene-3,17-dione; 4-acetylthio-6-methylenandrosta-1,4- iene-3,17-dione; 4-acetylthio-6-methylene-7α-methyl androsta - 1,4-diene-3,17-dione; 4-acetylthio-6-methylene-16α-fluoroandrosta-1 4-diene-3,17-dione; 4-acetylthio-6-methylene-16β-fl uoroandrosta-1,4-diene-3,17-dione; 4-acetylthio-6-methylene-7α-meth l-16α-fluoroandrosta-1,4-diene-3,17-dione; 4-acetyl thio-6-methylene-7α-methyl-16β-fluoroandrosta-1,4-diene-3,17-dione; 4-ethylthio-6-methylenandrosta-1,4-diene-3,17-dione; 4-ethylthio-6-methylene-7α-methylandrosta-1,4-diene-3,17-dione; 4 ethylthio-6-methylene-16α-fluoroandrosta-1,4-diene-3,17 -dione; 4 -ethylthio-6-methylene-16β-fluoroandrosta-1,4-diene-3 ,17-dione; 4-ethylthio -6-methylene-7α-methyl-16α-fluoroandrosta-1,4-diene-3,17-dione; 4-e hylthio-6-methylene-7α-methyl-16β-fluoroandrosta-1,4-di ene-3,17-dione; 1-methyl-4-mercapto-6-methylenandrosta -1,4-diene-3,17-dione; 1,7α-dimethyl-4-mercapto-6-methylenandrosta- ,4-diene-3,17-dione; 1-methyl-4-mercapto-6-methylen e-16α-fluoroandrosta-1,4-diene-3,17-dione; 1-methyl-4-mercapto-6-me hylene-16β-fluoroandrosta-1,4-diene-3,17-dione; 1,7 α-dimethyl-4-mercapto-6-methylene-16α-fluoroandrosta-1,4-diene-3,17-dio e; 1,7α-dimethyl-4-mercapto-6-methylene-16β-fluoroa ndrosta-1,4-diene-3,17-dione; 1-methyl-4-acetylthio-6-methylenandro ta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-acetylthio -6-methylenandrosta-1,4-diene-3,17-dione; 1-methyl-4-acetylthio-6-m thylene-16α-fluoroandrosta-1,4-diene-3,17-dione; 1- methyl-4-acetylthio-6-methylene-16β-fluoroandrosta-1,4-diene-3,17-dione 1,7α-dimethyl-4-acetylthio-6-methylene-16α-fluoroa ndrosta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-acetylthio-6-methylen -16β-fluoroandrosta-1,4-diene-3,17-dione 1-methyl-4 -ethylthio-6-methylenandrosta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-ethylthio-6-methylenandrosta -1,4-diene-3,17-dione; 1-methyl-4-ethylthio-6-methylene-16α-fluoroa drosta-1,4-diene-3,17-dione; 1-methyl-4-ethylthio-6 -methylene-16β-fluoroandrosta-1,4-diene-3,17-dione; 1,7α-dimethyl-4 ethylthio-6-methylene-16α-fluoroandrosta-1,4-diene-3,17 -dione; and 1,7α-dimethyl-4-ethylthio-6-methylene-16β-fluoroandrosta-1,4-diene-3,17-dione. Another preferred class of compounds according to the invention are the compounds of formula (I) wherein each of R₁, R₂ and R₃, independently, is hydrogen or C₁-C₆ alkyl; R₄ is hydrogen or fluorine; (x) represents a single bond or a double bond; and R is a group wherein one of R₉ and R₁₀ is hydrogen and the other is hydrogen or C₁-C₆ alkyl, and the pharmaceutically acceptable salts thereof. In the above preferred class, preferably R₁ is hydrogen or methyl; R₂ is hydrogen; R₃ is hydrogen, methyl or ethyl; and R₄ is hydrogen or fluorine; preferably one of R₉ and R₁₀ is hydrogen and the other is hydrogen, methyl or ethyl, a particularly preferred value for being amino. When R₁ is C₁-C₆ alkyl, preferably (x) represents a double bond. Examples of specific compounds of the above preferred class are: 4-amino-6-methylenandrost-4-ene-3,17-dione; 4-amino-6-meth lene-7α-methylandrost -4- ene-3,17-dione; 4-amino-6-methylene-16α-fluoroandrost-4-ene-3,17-di ne; 4-amino-6-methylene-16β-fluoroandrost-4-ene-3,1 7-dione; 4-amino-6-methylene-7αmethyl-16α-fluoroandrost-4-ene-3,17- ione; 4-amino-6-methylene-7α-methyl-16β-fluoroandro st-4-ene-3,17-dione; 4-amino-6-methylenandrosta-1,4-diene-3,17-dion ; 4-amino-6-methylene-7α-methylandrosta-1,4-diene-3 ,17-dione; 4-amino-6-methylene-16α-fluoroandrosta-1,4-diene-3,17-di ne; 4-amino-6-methylene-16β-fluoroandrosta-1,4-dien e-3,17-dione; 4-amino-6-methylene-7α-methyl-16α-fluoroandrosta-1,4- iene-3,17-dione; 4-amino-6-methylene-7α-methyl-16β- fluoroandrosta-1,4-diene-3,17-dione; 1-methyl-4-amino-6-methylenand osta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-amino-6- methylenandrosta-1,4-diene-3,17-dione; 1-methyl-4-amino-6-methylene 16α-fluoroandrosta-1,4-diene-3,17-dione; 1-methyl-4-amino-6-methylene-16β-fluoroandrosta-1,4-diene-3,17-di ne; 1,7α-dimethyl-4-amino-6-methylene-16α-fluoroand rosta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-amino-6-methylene-16β-f uoroandrosta-1,4-diene-3,17- dione; and the pharmaceutically acceptable salts thereof. The compounds of the invention may be prepared by a process comprising: A) treating a compound of formula (II) wherein R₁, R₂, R₃, R₄ and (x) are as defined above, by solvolysis such as to obtain a compound of formula (I) wherein R is a group -OR₅ wherein R₅ is hydrogen, C₁-C₆ alkyl or phenyl or benzyl group unsubstituted or ring-substituted as defined above; or B) etherifying a compound of formula (I) wherein R is -OH such as to obtain a compound of formula (I) wherein R is a group -OR₅ wherein R₅ is C₁-C₆ alkyl or a hydroxy protecting group; or C) reacting a compound of formula (II) with a compound of formula (III) R′₇ - SH (III) wherein R′₇ is hydrogen, C₁-C₆ alkyl or phenyl or benzyl group unsubstituted or ring-substituted as indicated above, so obtaining a compound of formula (I) wherein R is a group -SR₇ wherein R₇ either has one of the meanings reported above for R′₇ or is a group -SR₈ wherein R₈ is a steroidic residue as defined above under (vi) in which R₁, R₂, R₃, R₄ and (x) are the same as in the starting compound of formula (II); or D) acylating a compound of formula (I) wherein R is -OH or respectively -SH, with a reagent carrying a -COR₆ moiety, wherein R₆ is as defined above, so obtaining a compound of formula (I) wherein R is a group -OR₅ or, respectively, a group -SR₇ wherein R₅ and, respectively, R₇ are a group -COR₆ wherein R₆ is as defined above, or E) reacting a compound of formula (I) wherein R is -SH with a compound of formula (IV) R₈ - SH (IV) wherein R₈ is a defined above, so obtaining a compound of formula (I) wherein R is -SR₇ wherein R₇ is a group -SR₈ in which R₈ is as defined above; or F) reacting a compound of formula (II) with a compound of formula (V) M - N₃ (V) wherein M is an alkali metal or ammonium cation or a tri-C₁-C₆-alkylsilyl group, so obtaining a compound of formula (I) wherein R is the group -N₃; or G) reducing a compound of formula (I) wherein R is the group -N₃, so obtaining a compound of formula (I) wherein R is a group wherein R₉ and R₁₀ are both hydrogen; or H) alkylating a compound of formula (I) wherein R is a group wherein R₉ and R₁₀ are both hydrogen, so obtaining a compound of formula (I) wherein R is a group wherein at least one of R₉ and R₁₀ is C₁-C₆ alkyl; and, if desired, salifying a compound of formula (I) containing a salifiable group or obtaining a free compound from a salt and/or, if desired, separating a mixture of isomers of formula (I) into the single isomers. The solvolysis of a compound of formula (II) in order to obtain a compound of formula (I) wherein R is a group -OR₅ wherein R₅ is hydrogen may be carried out, e.g., by treatment with suitable mineral acids e.g., sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid, or a mixture thereof, at a temperature ranging from about the room temperature to about the reflux temperature. Preferably the reaction is carried out by treatment with a mixture of glacial acetic acid and concentrated sulfuric acid, at a temperature ranging from about 10°C to about 50°C, e.g., according to B. Camerino et al., 1956, Il Farmaco 7, 19. The solvolysis of a compound of formula (II) in order to obtain a compound of a formula (I) wherein R is a group -OR₅ wherein R₅ is C₁-C₆ alkyl, may be, e.g., carried out by treatment with a suitable C₁-C₆ alkyl-alcohol in aqueous solution,in th e presence of an alkali which is, preferably , an alkali metal, e.g., sodium or potassium, hydroxide, at a temperature ranging, e.g., from about 20°C to the reflux temperature, for reaction time varying, e.g., from about 1 hour to about 48 hours, for instance according to B. Camerino et al., 1962, Gazz. Chim. It. 92, 709. In similar way, solvolysing the compound (II) with the appropriate phenol derivative or benzyl alcohol derivative, a compound (I) wherein R is a group -OR₅ in which R₅ is a phenyl or benzyl group either unsubstituted or ring-substituted as indicated above, may be obtained. The etherification of a compound of formula (I) wherein R is -OH to give a compound of formula (I) wherein R is a group -OR₅ wherein R₅ is C₁-C₆ alkyl or a hydroxy protecting group, may be carried out by the usual procedures described in the organic chemistry for converting alcohol into ethers; for instance C₁-C₆ alkyl ether may be obtained by reaction with the appropriate diazoalkane or C₁-C₆ alkyl halide under standard conditions, and, e.g., silyl ethers may be prepared by reacttion with the appropriate silyl halide in the presence of a base, again using conventional procedures. The reaction between a compound of formula (II) and a compound of formula (III) wherein R′₇ is hydrogen (i.e. hydrogen sulfide) leading, by oxirane ring cleavage, to a compound of formula (I) wherein R is a group -SR₇wherein R₇ is hydrogen may be carried out in presence of a base, either organic such as, for instance, pyridine or a tri-C₁-C₆-alkylamine e.g. triethylamine, or inorganic such as, e.g., NaOH or KOH, operating in an inert solvent, such as, for example, methanol, ethanol, water, dioxane, or dimethoxyethane, and under inert atmosphere. When the reaction is carried out under air or oxygen atmosphere, the dimeric disulfide is obtained, i.e. the compound of formula (I) wherein R is -SR₇ with R₇ being a group -SR₈ in which R₈ is a steriodic residue as defined above under (vi) having for R₁, R₂, R₃, R₄ and (x) the same meanings as the starting compound of formula (II). The reacton between a compound of formula (II) and a compound of formula (III) wherein R′₇ is C₁-C₆ alkyl or a phenyl or benzyl group as defined above leading, by oxirane ring cleavage, to a compound of formula (I) wherein R is a group -SR₇ wherein R₇ is C₁-C₆ alkyl or a phenyl or benzyl group as defined above, may be carried out in presence of an acid such as, for example, polyphosphoric acid, operating in an inert solvent which may be, for instance, dioxane, dimethoxyethane, water, methanol or ethanol at a temperature between about 0°C and about 50°C. The acylation of a compound of formula (I) wherein R is -OH or,respectively,-SH, in order to obtain a compound of formula (I) wherein R is a group -OR₅ or, respectively, a group -SR₇wherein R₅ and, respectively, R₇ are a group -COR₆ wherein R₆ is as defined above, may be performed by reaction with a suitable acylating agent carrying the -COR₆ moiety, which may be,for example,a reactive derivative of the appropriate carboxylic acid, such as e.g., a halide, preferably the chloride or the anhydride or a mixed anhydride, thereof, in the presence of a basic agent,preferably an organic base,such as,e.g.,pyridine. The reaction between a compound of formula (I), wherein R is -SH and a compound of formula (IV), in order to obtain a compound of formula (I) wherein R is a group -SR₇ wherein R₇ is -SR₈ with R₈ as defined above, may be performed according to known methods for the formation of disulfides,e.g. as described in Comprehensive Organic Chemistry, Vol.3, pag. 283-6, Pergamon Press. When M in the compound (V) is an alkali metal, this is, preferably, sodium, potassium ot lithium; when M is a tri-C₁-C₆ alkyl silyl group, this is, preferably, trimethylsi lyl o r dimethyl-tert.butylsilyl. Preferred compounds (V) are sodium azide, lithium azide, trimethylsilyl azide and dimethyl tert.butyl silyl azide. The reaction between a compound of formula (II) and a compound of formula (V) is preferably carried out in a dipolar aprotic solvent such as, for instance, N,N-dimethyl-formamide or dimethylsulfoxide; some water or an aqueous alcoholic, e.g. methanolic or ethanolic, solution may be added, if desired, to increase the solubility of the azide (V). The reaction temperature may be,e.g., from about 0°C to about 60°C. Some acid, e.g. sulfuric acid may be added, if desired, to increase the reactivity of the oxirane ring. The reduction of a compound of formula (I) wherein R is the group -N₃ in order to obtain a compound of formula (I) wherein R is a group wherein R₉ and R₁₀ are both hydrogen, may be carried out following known methods, for instance, with a variety of reducing agents, e.g. propane-1,3-dithiol in triethylamine, as described in Tetr. Lett., 39 , 3633 (1978); dithiolthreitol in aqueous solutions;mercaptoacetic acid and triethylamine; or, for instance, triphenylphosphine in tetrahydrofuran and aqueous solution, as described, e.g., in Bull. Soc. Chim.Fr., 1985, 815. The alkylation of a compound of formula (I) wherein R is a group wherein R₉ and R₁₀ are both hydrogen to obtain a corresponding compound of formula (I) wherein R is a group wherein at least one of R₉ and R₁₀ is C₁-C₆ alkyl, may be carried out by reaction with a suitable alkylating agent which may be, e.g., a C₁-C₆ alkyl halide, in particular iodide, or di-C₁-C₆-alkyl-sulfate; for obtaining a compound of formula (I) wherein R is a group wherein at least one of R₉ and R₁₀ is methyl or ethyl suitable alkylating agents are, e.g., methyl iodite, dimethylsulfate or, respectively, ethyliodide and diethylsulfate. Reaction conditions well known to the skilled in the art and well described in the organic chemistry may be followed: see, e.g., Lucier et al., Org. Synth. 44 , 72 (1964). A compound of formula (II) wherein (x) is single bond and R₁, R₂, R₃, and R₄ are as defined above may be prepared by epoxidation of a compound of formula(VI) wherein R₁, R₂, R₃ and R₄ are as defined above. The epoxidation may be carried out by treatment with a suitable oxi dizing agent which may be, for instance, concentrated, e.g. 36%, hydrogen peroxide in an alcoholic alkali-metal hydroxide solution, preferably KOH or NaOH in methanol, at a temperature ranging e.g., approximately, from 0°C to 25°C for a time of from about 2 hrs to several days. A compound of formula (II) wherein (x) is a double bond and R₁, R₂, R₃ and R₄ are as defined above, may be prepared by dehydrogenating a corresponding compound of formula (II) wherein (x) is a single bond, following known methods, e.g. by treatment with 2,3-dichloro-5,6-dicyano benzoquinone as reported, e.g., by D. Walker and J.D.Hiebert in Chem. Rev. 67 , 153 (1967) or with selenium dioxide, chloranil or benzeneseleninic anhydride. Preferably the said reaction is performed with benzeneseleninic anhydride in an inert solvent such as, e.g. chlorobenzene or carbon tetrachloride, at a temperature ranging, e.g., from about 60°C to about 120°C and for reaction times between about two hours and about 48 hours. A compound of formula (VI) may be in its turn obtained by alkylidenation of a compound of formula (VIII) wherein R₁, R₃ and R₄are as defined above, according to known methods, e.g. according to the method of K. Annen, Synthesis, 34 (1982). Preferably a compound of formula (VII) is react ed with an unsubstituted or appropriately C₁-C₆ alkyl substituted formaldehyde diethylacetal in refluxing chloroform in the presence of phosphoryl chloride and sodium acetate. Alternatively, the same reaction may be carried out in other inert solvents, e.g. 1,2-dichloroethane, diethyl ether or dioxane, and in the presence of other suitable condensing agents,e.g.,phosphorous pentoxide or p-toluenesulphonic acid. The compounds of formula (VII) wherein R₃ is hydrogen are known compounds, or compounds that can be prepared by known methods from known compounds. The compounds of formula (VII) wherein R₃ is C₁-C₆ alkyl may be, e.g., obtained by alkylation of a compound of formula (VIII) wherein R and R₄ are as defined above, according to known methods. For instance, alkyl lithium or alkyl magnesium halides are reacted with a copper (I) halide,e.g.iodide,in an ethereal solvent,e.g. diethyl ether, at 0°C - 10°C, to form the alkyl copper complex,which is then added to a solution of the compound (VIII) in a suitable solvent, e.g.diethyl ether or tetrahydrofuran, at a temperature ranging from about 0°C to about 50°C. The compound of formula (VIII), wherein R₁ and R₄ are both hydrogen is a known, commercially available compound. The compounds of formula (VIII) wherein R₁ and/or R₄ are different from hydrogen may be, e.g., obtained by dehydrogenation of a corresponding compound of formula (VIII) wherein R₃ is hydrogen, according to known methods. In particular, the compounds of formula (VII) and (VIII) wherein R₄ is fluorine may be prepared form the corresponding compounds of formula (VII) and (VIII) wherein R₄ is hydrogen by known methods, for instance by the process described by J.A. Katzenellenbogen et al., in J. Org. Chem., 49 , 4900 (1984). The compounds of the present invention are inhibitors of the biotransformation of androgens into estrogens, i.e., they are steroidal aromatase inhibitors. The aromatase inhibitory activity of these compounds is shown, e.g., by the fact that they are active in the in vitro test described by Thompson and Siiteri (E.A. Thompson and P.K.Siiteri, J. Biol. Chem. 249 , 5364, 1974) which utilizes the human placental microsomal fraction as enzyme source. In this test the aromatization rate of androstenedione into estrone was evaluted by incubating [1β,2β-³H]androstenedione (50 nM) in the presence of NADPH with the enzyme preparation and by measuring the amount of ³H₂O formed during 20 min incubation at 37°C. By virtue of their ability to inhibit aromatase and, consequently, to reduce estrogen levels, the new compounds of the invention may be useful in the treatment and prevention of various estrogen dependent diseases, e.g., breast, endometrial, ovarian and pancreatic cancers, gynecomastia, benign breast disease, endometriosis, polycystic ovarian disease and precocious puberty. Another application of the compounds of the invention may be in the therapeutic and/or prophylactic treatment of prostatic hyperplasia, a disease of the estrogen dependent stromal tissue. The new compounds can find also use for the treatment of male infertility associated with oligospermia and for female fertility control, by virtue of their ability to inhibit ovulation and egg nidation. In view of their high therapeutic index, the compounds of the invention can be used safely in medicine. For example, the approximate acute toxicity (LD₅₀) of the compounds of the invention in the mouse, determined by single administration of increasing doses and measured on the seventh day after the treatment was found to be negligible. The compounds of the invention can be administered in a variety of dosage forms, e.g. orally, in the form of tablets, capsules, sugar of film coated tablets, liquid solutions or suspensions; rectall y, in the form of suppositories; parenterally, e.g. intramuscularly, or by intravenous injection of infusion; or topically. The dosage depends on the age, weight, conditions of the patient and administration route; for example the dosage adopted for oral administration to adult humans may range from about 10 to about 150-200 mg pro dose, from 1 to 5 times daily. The invention includes pharmaceutical compositions comprising a compound of the invention in association with a pharmaceutically acceptable excipient (which can be a carrier or diluent). The pharmaceutical compositions containing the compounds of the invention are usually prepared following conventional methods and are administered in a pharmaceutically suitable form. For example, the solid oral forms may contain, together with the active compound, diluents, e.g., lactose, dextrose, saccharose, cellulose, corn starch or potato starch; lubricants, e.g. silica, talc, stearic acid, magnesium or calcium stearate; and/or polyethylene glycols; binding agents, e.g. starches, arabic gums, gelatin, methylcellulose, carboxymethylcellulose or polyvinil pyrrolidone; disaggregating agents, e.g. a starch, alginic acid, algina tes or sodium starch glycolate; effervescing mixtures; dyestuff; sweeteners; wetting agents, such as lecithin, polysorbates, laurysulphates; and, in general, non-toxic and pharmacologically inactive substances used in pharmaceutical formulations. Said pharmaceutical preparations may be manufactured in known manner, for example, by means of mixing, granulating, tabletting, sugar-coating, or film-coating processes. The liquid dispersions for oral administration may be e.g. syrups, emulsions and suspensions. The syrup may contain as carrier, for example, saccharose or saccharose with glycerine and/or mannitol and/or sorbitol. The suspensions and the emulsions may contain as carrier, for example, a natural gum, agar, sodium alginate, pectin, methylcellulose, carboxymethylcellulose, or polyvinyl alcohol. The suspensions or solutions for intramuscular injections may contain, together with the active compound, a pharmaceutically acceptable carrier, e.g. sterile water, olive oil, ethyl oleate, glycols, e.g. propylene glycol, and, if desired, a suitable amount of lidocaine hydrochloride. The solutions for intravenous injections or infusione may contain as carrier, for example, sterile water or, preferably, they may be in the form of sterile, aqueous, isotonic saline solutions. The suppositories may contain together with the active compound a pharmaceutically acceptable carrier,e.g. cocoa-butter, polyethylene glycol, a polyoxyethylene sorbitan fatty acid ester surfactant or lecithin. Compositions for topical applications such as, e.g., creams, lotions or pastes, may be, e.g., prepared by admixing the active ingredient, with a conventional oleaginous or emulsifying excipient. The following examples illustrate but do not limit the invention. EXAMPLE I 6-methylenandrost-4-ene-3,17-dione (VI, R₁=R₂=R₃=R₄=H, (x)=single bond). A mixture of androst-4-ene-3,17-dione (32 g, 111 mmole), formaldehyde diethylacetal (620 ml), phosphorous oxychloride (78.6 ml, 827 mmole),anhydrous sodium acetate (20.7g, 252 mmole) and chloroform (1150 ml) is stirred and refluxed during 5 hrs. To the cooled reaction mixture is added dropwise, and in the order, a 40% potassium carbonate aqueous solution (800 ml) and a 2 N sodium hydroxide aqueous solution (1320 ml) under vigorous stirring. After 1 hour of additional stirring, the organic phase is separated and the aqueous phase is extracted with two portions of chloroform (300 ml + 200 ml). The combined organic phases are washed with water, dried over anhydrous calcium chloride, filtered and evaporated in vacuo. The resulting residue is column chromatograp hed over silica gel. Elution with n-hexane: ethyl acetate 80:20 yields a solid (20 g) which is crystallised from isopropyl ether (240 ml). There are obtained 14 g (42% yield) of the title compound, m.p. 155-60°C. In analogous fashion and starting from the appropriate precursors of formula (VII) the following compounds can be prepared : 6-methylene-7α-methylandrost-4-ene-3,17-dione; 6-methylene-16 -fluoroandrost-4-ene-3,17-dione; 6-methylene-16β-fl uoroandrost-4-ene-3,17-dione; 6-methylene-7α-methyl-16α-fluoroandro t-4-ene-3,17-dione; 6-methylene-7α-methyl-16β-fluor oandrost-4-ene-3,17-dione; 1β-methyl-6-methylenandrost-4-ene-3,17-d one; 1β,7α- dimethyl-6-methylenandrost-4-ene-3,17-dione; 1β-methyl-6-methylene- 6α-fluoroandrost-4-ene-3,17-dione; 1β-methyl-6-meth ylene-16β-fluoroandrost-4-ene-3,17-dione; 1β,7α-dimethyl-6-methylen -16α-fluoroandrost-4-ene-3,17-dione; and 1β,7α-dimethyl-6-methylene-16β-fluoroandrost-4-ene-3,17-dione. EXAMPLE II 4,5-epoxy-6-methylenandrostane-3,17 dione (II, R₁=R₂=R₃=R₄=H, (x)=single bond). To a solution of 6-methylenandrost-4-ene-3,17-dione (5 g, 16.7 mmole) in methanol (200 ml) cooled at 0°C is added a cold 36% hydrogen peroxide solution(17 ml) and a cold 2% sodium hydroxide aqueous solution. The resulting reaction mixture is stirred at 0-5°C during 24 hrs, then it is poured into iced water (1400 ml) with vigorous stirring. The resulting precipitate is filtered, washed with water and dried in vacuo. There are obtained 4.2 g (80% yield) of the title compound, NMR (CDCl₃, δ): 0.90 (3H,s) 0.97 (3H,s) 3.52 (1H,s) 4.92 (1H, br s) 5.06 (1H, br s) In analogous fashion and starting from the appropriate precursors of formula (VI) the following compounds can be prepared: 4,5-epoxy-6-methylene-7α-methylandrostane-3,17-dione; 4.5-epoxy-6-methylene-16α-fluoroandrostane-3,17-dione; 4,5-epoxy-6-methylene-16β-fluoroandrostane-3,17-dione; 4,5-epox -6-methylene-7α-methyl-16α-fluoroandrostane-3,17-dione; 4,5-epoxy-6-methylene-7α-methyl-16β-fluoroandrostane-3,17--dione; /DL>4,5-epoxy-1β-methyl-6-methylenandrostane-3,17-dione ; 4,5-epoxy-1β,7α-dimethyl-6-methylenandrostane-3,17-dione; 4,5 epoxy-1β-methyl-6-methylene-16α-fluoroandrostane-3,17-d ione; 4,5-epoxy-1β-methyl-6-methylene-16β-fluoroandrostane-3,17-dio e; 4,5-epoxy-1β,7α-dimethyl-6-methylene-16α-fluoroa ndrostane-3,17-dione; and 4,5-epoxy-1β,7α-dimethyl-6-methylene- 6β -fluoroandrostane-3,17-dione. EXAMPLE III 4,5-epoxy-6-methylenandrost-1-ene-3,17-dione (II, R₁=R₂=R₃=R₄=H, (x)=double bond). A mixture of 4,5-epoxy-6-methylenandrostane-3,17-dione (3g, 9.6 mmole) and dichlorodicyanobenzoquinone (1.7 g) dissolved in dioxane (60 ml) are refluxed during 15 hrs. The cooled reaction mxiture is filtered through alumina and the filtrate is evaporated in vacuo. The resulting residue is taken up with ethyl acetate, washed with water and dried over sodium sulfate. The resulting solution is filtered and evaporated in vacuo to yield a crude product which is purified by column chromatography on silica gel eluting with a 10-40% gradient of ethyl acetate in n-hexane. There are obtained 1.5g (51% yield) of the title compound, NMR (CDCl₃,δ): 0.93 (3H,s) 1.13 (3H,s) 3.71 (1H, d) 5.03 (2H, m) 5.86 (1H, d) 6.78 (1H, d) In analogous fashion and starting from the appropriate precursors of formula (II) wherein (x) is single bond, the following compounds can be prepared: 4,5-epoxy-6-methylene-7α-methylandrost- 1-ene-3,17-dione; 4,5-epoxy-6-methylene-16α-fluoroandrost-1-ene-3,1 -dione; 4,5-epoxy-6-methylene-16β-fluoroandrost-1-ene-3,17-dione; 4,5 epoxy-6-methylene-7α-methyl-16α-fluoroandrost-1-ene-3,1 7-dione; 4,5-epoxy-6-methylene-7α-methyl-16β-fluoroandrost-1-ene-3, 7-dione; 4,5-epoxy-1-methyl-6-methylenandrost-1-ene -3,17-dione; 4,5-epoxy-1,7α-dimethyl-6-methylenandrost-1-ene-3,17-d one; 4,5-epoxy-1 -methyl-6-methylene-16α-fluoroandrost-1-ene-3,17-dione; 4,5-epoxy-1 methyl-6-methylene-16β-fluoroandrost-1-ene-3,17-dione; 4,5-epoxy-1,7α-dimethyl-6-methylene-16α-fluoroandrost-1-ene-3,17 dione; and 4,5-epoxy-1,7α-dimethyl-6-methylene-16β-fluoroandros -1-ene-3,17-dione. EXAMPLE IV 4-hydroxy-6-methylenandrost-4-ene-3,17-dione (I, R=-OH, R₁=R₂=R₃=R₄=H, (x)=single bond). 4,5-epoxy-6-methylenandrostane -3,17-dione (3.6 g, 11.5 mmole) is added portionwise to a stirred cooled mixture of glacial acetic acid (98 ml) and conc. sulfuric acid (2 ml). The resulting reaction mixture is stirred at 0-5°C during 24 hrs. and then poured into a mixture of ice and water (900 g). The resulting precipitate is filtered off, dried and purified by column chromatography on silica gel eluting with methylene chloride: ethyl acetate 95:5. There are obtained 1.08 g (30% yield) of the title compounds Elemental analysis : Calculated % (found %) C 76.40 (76.30) H 8.34 ( 8.29) NMR (CDCl₃,δ ): 0.91 (3H,s) 1.13 (3H,s) 5.10 (1H,dd) 5.28 (1H,dd) 6.1 (1H,s) In analogous fashion and starting from the appropriate precursors of formula (II) the following compounds can be prepared: 4-hydroxy-6-methylene-7α-methylandrost-4-ene-3,17-dione;< DL> 4-hydroxy-6-methylene-16α-fluoroandrost-4-ene-3,17-d ione; 4-hydroxy-6-methylene-16β-fluoroandrost-4-ene-3,17-dione; 4-h droxy-6-methylene-7α-methyl-16α-fluoroandrost-4-ene-3,1 7-dione; 4-hydroxy-6-methylene-7α-methyl-16β-fluoroandrost-4-ene-3, 7-dione; 4-hydroxy-6-methylenandrosta -1,4-diene-3,17-dione; 4-hydroxy-6-methylene-7α-methylandrosta-1,4- iene-3,17-dione; 4-hydroxy-6-methylene-16α-fluoroan drosta-1,4-diene-3,17-dione; 4-hydroxy-6-methylene-16β-fluoroandros a-1,4-diene-3,17-dione; 4-hydroxy-6-methylene-7α-me thyl-16α-fluoroandrosta-1,4-diene-3,17-dione; 4-hydroxy-6-methylene 7α-methyl-16β-fluoroandrosta-1,4-diene-3,17-dione; 1-methyl-4-hydroxy-6-methylenandrosta-1,4-diene-3,17-dione; 1,7α-di ethyl-4-hydroxy-6-methylenandrosta-1,4-diene-3,17-dione ; 1-methyl-4-hydroxy-6-methylene-16α-fluoroandrosta-1,4-diene-3,17- ione; 1-methyl-4-hydroxy-6-methylene-16β-fluoroandr osta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-hydroxy-6-methylene-16α- luoroandrosta-1,4-diene-3,17-dione; and 1,7α-di methyl-4-hydroxy-6-methylene-16β-fluoroandrosta-1,4-diene-3,17-dione. EXAMPLE V 4-methoxy-6-methylenandrost -4-ene-3,17-dione (I, R=OCH₃, R₁=R₂=R₃=R₄=H, (x)=single bond). To a stirred suspension of 4,5-epoxy-6-methylenandrostane-3,17-dione (0.630 g,2 mmole)in methanol (63 ml) is added a 4 N sodium hydroxide aqueous solution (6.3 ml). The resulting mixture is refluxed for 1 hr, cooled to room temperature, evaporated in vacuo, taken up with water, neutralised with a 37% hydrochloric acid solution and kept at 0-5°C overnight. The resulting precipitate is filtered off, washed with water, dried and purified by flash column chromatography on silica gel eluting with n-hexane: ethyl acetate 60:40. There are obtained 0.530 g (75% yield) of the title compound, m.p. 196°-198°C. Elemen tal analysis : Calculated % (found %) C 76.83 (76.14) H 8.54 ( 8.60) NMR (CDCl₃,δ) 0.90 (3H, s) 1.14 (3H, s) 3.60 (3H, s) 5.10 (1H,dd) 5.30 (1H,dd) In analogous fashion and starting from the appropriate precursors of formula (II) the following compounds can be pre pared : 4-methoxy-6-methylene-7α-methylandrost-4-ene-3,17-dione; 4-me hoxy-6-methylene-16α-fluoroandrost-4-ene-3,17-dione; 4-methoxy-6-methylene-16β-fluoroandrost-4-ene-3,17-dione; 4-metho y-6-methylene-7α-methyl-16α-fluoroandrost-4-ene-3,17-di one; 4-methoxy-6-methylene-7α-methyl-16β-fluoroandrost-4-ene-3,17-d one; 4-methoxy-6-methylenandrosta-1,4-diene-3,17-di one; 4-methoxy-6-methylene-7α-methylandrosta-1,4-diene-3,17-dione;< DL> 4-methoxy-6-methylene-16α-fluoroandrosta-1,4-diene-3 ,17-dione; 4-methoxy-6-methylene-16β-fluoroandrosta-1,4-diene-3,17- ione; 4-methoxy-6-methylene-7α-methyl-16α-fluoroand rosta-1,4-diene-3,17-dione; 4-methoxy-6-methylene-7α-methyl-16β-flu roandrosta-1,4-diene-3,17-dione; 1-methyl-4-methoxy -6-methylenandrosta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-methoxy-6 methylenandrosta-1,4-diene-3,17-dione; 1-methyl-4-m ethoxy-6-methylene-16α-fluoroandrosta-1,4-diene-3,17-dione; 1-methy -4-methoxy-6-methylene-16β-fluoroandrosta-1,4-diene-3,1 7-dione; 1,7α-dimethyl-4-methoxy-6-methylene-16α-fluoroandrosta-1,4 diene-3,17-dione; and 1,7α-dimethyl-4-methoxy-6 -methylene-16β-fluoroandrosta-1,4-diene-3,17-dione. EXAMPLE VI 4-amino-6-methylenandrost-4-ene-3,17-dione (I, R=NH₂, R₁=R₂=R₃=R₄=H, (x)=single bond). To a stirred solution of 4,5-epoxy-6-methylenandrostane-3,17-dione (0.39 g, 1.25 mmole) in dry dimethylsulfoxide (8 ml) is added conc. sulfuric acid (0.1 ml) and sodium azide (1.5 g). The resulting reaction mixture is heated at about 100°C during 15 min., cooled,poured into a mixture of water (50 ml) and conc. hydrochloric acid (4 ml), and extracted with ethyl acetate (3 x 50 ml). The combined extracts are dried over sodium sulfate, filtered and evaporated in vacuo to yield a solid which is purified by flash column chromatography eluting with n-hexane: ethyl acetate 1:1. There are obtained 0.16g of 4-azido-6-methylenandrost-4-ene-3,17-dione (I, R=N₃) which are dissolved in tetrahydrofuran (2 ml) and treated by the portionwise addition of triphenyl phosphine (0.2 g) at room temperature, followed by the addition of water (0.5 ml). The resulting reaction mixture is heated at reflux for 24 hrs, cooled,diluted by the addition of a 1N HCl aqueous solution (50 ml) and washed with methylene chloride (2 x 50 ml) which is discarded. The aqueous phase is adjusted to pH 10 and extracted with methylene chloride (3 x 50 ml). The combined organic extracts are washed with brine, dried over sodium sulfate and evaporated in vacuo. The resulting residue is purified by flash column chromatography eluting with n-hexane: diethyl ether 1:2. There are obtained 0.13 g (80% yield) of the title compound. Elemental analysis: Calculated % (found %) C 76.68 (76.51) H 8.63 ( 8.70) N 4.47 ( 4.52) NMR (CDCl₃,δ) 0.91 (3H, s) 1.13 (3H, s) 3.00 (2H, br s) 5.11 (1H,dd) 5.30(1H,dd) In analogous fashion and starting from the appropriate precursors of formula (II) the following compounds can be prepared: 4-amino-6-methylene-7α-methylandrost-4-ene-3,17-dione; 4-amino-6-methylene-16α-fluoroandrost-4-ene-3,17-dione ; 4-amino -6-methylene-16β-fluoroandrost-4-ene-3,17-dione; 4-amino-6-methylen -7α-methyl-16α-fluoroandrost-4-ene-3,17-dione; 4-am ino-6-methylene-7α-methyl-16β-fluoroandrost-4-ene-3,17 -dione; 4-amino-6-methylenandrosta-1,4-diene-3,17-dione; 4-amin -6-methylene-7α-methylandrosta-1,4-diene-3,17-dione; 4-amino-6-methylene-16α-fluoroandrosta-1,4-diene-3,17-dione; 4-am no-6-methylene-16β-fluoroandrosta-1,4-diene-3,17-dione; 4-amino-6-methylene-7α-methyl-16α-fluoroandrosta-1,4-diene-3,17-d one; 4-amino-6-methylene-7α-methyl-16β-fluoroandros ta-1,4-diene-3,17-dione; 1-methyl-4-amino-6-methylenandrosta-1,4-di ne-3,17-dione; 1,7α-dimethyl-4-amino-6-methylenandr osta-1,4-diene-3,17-dione; 1-methyl-4-amino-6-methylene-16α-fluoroa drosta-1,4-diene-3,17-dione; 1-methyl-4-amino-6-met hylene-16β-fluoroandrosta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-ami o-6-methylene-16α-fluoroandrosta-1,4-diene-3,17-dione; and 1,7α-dimethyl-4-amino-6-methylene-16β-fluoroandrosta-1,4-di ne-3,17-dione. EXAMPLE VII 4-mercapto-6-methylenandrost-4-ene-3,17-dione (I, R=-SH, R₁=R₂=R₃=R₄=H, (x)=single bond). To a stirred solution of 4,5-epoxy-6-methylenandrostane-3,17-dione (0.40 g, 1.25 mmole) in dioxane (12 ml)and ethanol (12 ml) is added a solution of technical sodium hydrosulfide (0.55 g) in ethanol (25 ml) dropwise under nitrogen at 10°C. The resulting reaction mixture is stirred at room temperature for 1 hour, neutralised with glacial acetic acid (1 ml) and extracted with chloroform (50 ml). The organic extract is washed with water, a saturated NaHCO₃ aqueous solution, water, and then dried over sodium sulfate. The solvent is evaporated in vacuo and the crude product is column chromatographed over silica gel eluting with benzene. There are obtained 0.227 g(55%) of the title compound, m.p.195-7° C, Elemental analysis : Calculated % (found %) C 72.72 (72.64) H 7.87 ( 7.95) S 9.69 ( 9.50) I.R. (KBr, cm⁻¹): 2560, 1730, 1660, 1560 In analogous fashion and starting from the appropriate precursors of formula (II), the following compounds can be prepared: 4-mercapto-6-methylene-7α-methylandrost-4-ene-3,17-dione; 4-mercapt -6-methylene-16α-fluoroandrost-4-ene-3,17-dione; 4-mercapto-6-methylene-16β-fluoroandrost-4-ene-3,17-dione; 4- ercapto-6-methylene-7α-methyl-16α-fluoroandrost-4-ene-3 ,17-dione; 4-mercapto-6-methylene-7α-methyl-16β-fluoroandrost-4-ene 3,17-dione; 4-mercapto-6-methylenandrosta-1,4-diene -3,17-dione; 4-mercapto-6-methylene-7α-methylandrosta-1,4-diene-3,1 -dione; 4-mercapto-6-methylene-16α-fluoroandrosta-1 ,4-diene-3,17-dione; 4-mercapto-6-methylene-16β-fluoroandrosta-1,4- iene-3,17-dione 4-mercapto-6-methylene-7α-methyl-16 α-fluoroandrosta-1,4-diene-3,17-dione; 4-mercapto-6-methylene-7α-me hyl-16β-fluoroandrosta-1,4-diene-3,17-dione; 1-meth yl-4-mercapto-6-methylenandrosta-1,4-diene-3,17-dione; 1,7α-dimethy -4-mercapto-6-methylenandrosta-1,4-diene-3,17-dione; 1-methyl-4-mercapto-6-methylene-16α-fluoroandrosta-1,4-diene-3,17-dio e; 1-methyl-4-mercapto-6-methylene-16β-fluoroandros ta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-mercapto-6-methylene-16α-f uoroandrosta-1,4-diene-3,17-dione; and 1,7α-dimethyl-4-mercapto-6-methylene-16β-fluoroandrosta-1,4-die e-3,17-dione. EXAMPLE VIII 4-ethylthio-6-methylenandrost-4-ene-3,17-dione (I, R=-SCH₂CH₃, R₁=R₂=R₃=R₄=H, (x)=single bond). To a stirred solution of 4,5-epoxy-6-methylenandrostane-3,17-dione (0.78 g, 2.47 mmole) in dioxane (30 ml) is added ethylthiol (1.5 ml) and polyphosphoric acid (1.5 g) at room temperature under nitrogen. The reaction mixture is stirred for 6 hours and allowed to stand for a further 40 hours, then it is poured into a mixtu re of water and crushed ice, neutralised with sodium bicarbonate (3 g) and extracted with ethyl acetate. The combined extracts are washed with brine and dried over sodium sulfate. The solution is evaporated in vacuo and the resulting residue is column chromatographed over silica gel. Elution with benzene affords 3,4-bis (ethylthio)-6-methylenandrost-3-ene-17-one (0.410 g). Further elution with benzene : ethyl acetate 90:10 affords the title product. The former product dissolved in chloroform (30 ml) is treated with gaseous HCl during 3 hrs with cooling to give, after evaporation of the solvent, more title product (0.20 g). The two aliquots are combined and crystallised from methanol to yield the title compound (0.350 g, 40% yield), m.p. 140-5°C, Elemental analysis : Calculated % (found %) C 73.74 (73.61) H 8.37 ( 8.44) S 8.93 ( 9.01) I.R. (KBr, cm⁻¹): 1740, 1680, 1555 In analogous fashion and starting from the appropriate precursors of formula (II) the following compounds can be prepared: 4-ethylthio-6-methylene-7α-methylandrost-4-ene-3,17-dione 4-ethylthio-6-methylene-16α-fluoroandrost-4-ene-3, 17-dione; 4-ethylthio-6-methylene-16β-fluoroandrost-4-ene-3,17-dion ; 4-ethylthio-6-methylene-7α-methyl-16α-fluoroandro st-4-ene-3,17-dione; 4-ethylthio-6-methylene-7α-methyl-16β-fluoroan rost-4-ene-3,17-dione; 1-methyl-4-ethylthio-6-methy lenandrosta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-ethylthio-6-methy enandrosta-1,4-diene-3,17-dione; 1-methyl-4-ethylth io-6-methylene-16α-fluoroandrosta-1,4-diene-3,17-dione; 1-methyl-4- thylthio-6-methylene-16β-fluoroandrosta-1,4-diene-3,17- dione: 1,7α-dimethyl-4-ethylthio-6-methylene-16α-fluoroandrosta-1,4 diene-3,17-dione; 1,7α-dimethyl-4-ethylthio-6-methy lene-16β-fluoroandrosta-1,4-diene-3,17-dione; 4-ethylthio-6-methyle androsta-1,4-diene-3,17-dione; 4-ethylthio-6-methyl ene-7α-methylandrosta-1,4-diene-3,17-dione; 4-ethylthio-6-methylene-16α-fluoroandrosta-1,4-diene-3,17-dione;< DL> 4-ethylthio-6-methylene-16β-fluoroandrosta-1,4-diene -3,17-dione; 4-ethylthio-6-methylene-7α-methyl-16α-fluoroandrosta-1 4-diene-3,17-dione; and 4-ethylthio-6-methylene-7α-methyl-16β-fluoroandrosta-1,4-diene- ,17-dione. EXAMPLE IX 4-acetoxy-6-methylenandrost-4-ene-3,17-dione (I, R=-OCOCH₃, R₁=R₂=R₃=R₄=H, (x)=single bond). To a cooled solution of 4-hydroxy-6-methylenandrost-4-ene-3,17-dione (0.40 g, 1.27 mmole) in dry pyridine (3 ml) is added acetic anhydride (1 ml). The mixture is kept at 0-5°C overnight, then it is poured into cold water. The resulting precipitate is filtered off, thoroughly washed with water, dried in vacuo and crystallised from methanol: acetone 50:40. There are obtained 0.35 g (77% yield) of the title compound, m.p.: 183-5°C. In analogous fashion and starting from the appropriate precursors of formula (II) the following compounds can be prepared: 4-acetoxy-6-methylene-7α-methylandrost-4-ene-3,17-dione;< DL> 4-acetoxy-6-methylene-16α-fluoroandrost-4-ene-3,17-d ione; 4-acetocy-6-methylene-16β-fluoroandrost-4-ene-3,17-dione; 4-acetoxy-6-methylene-7α-methyl-16α-fluoroandrost-4-ene -3,17-dione; 4-acetoxy-6-methylene-7α-methyl-16β-fluoroandrost-4-en -3,17-dione; 4-acetoxy-6-methylenandrosta-1,4-diene -3,17-dione; 4-acetoxy-6-methylene-7α-methylandrosta-1,4-diene-3,17 dione; 4-acetoxy-6-methylene-16α-fluoroandrosta-1,4 -diene-3,17-dione; 4-acetocy-6-methylene-16β-fluoroandrosta-1,4-die e-3,17-dione; 4-acetoxy-6-methylene-7α-methyl-16α-fluoroandrosta-1,4-diene-3,17 dione; 4-acetoxy-6-methylene-7α-methyl-16β-fluoroan drosta- 1,4-diene-3,17-dione; 1-methyl-4-acetoxy-6-methylenandrosta-1,4-die e-3,17-dione; 1,7α-dimethyl-4-acetoxy-6-methylenand rosta-1,4-diene-3,17-dione; 1-methyl-4-acetoxy-6-methylene-16α-fluo oandrosta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-ace toxy-6-methylene-16α-fluoroandrosta-1,4-diene-3,17-dione; 1,7α-dime hyl-4-acetoxy-6-methylene-16β-fluoroandrosta-1,4-diene- 3,17-dione; 4-acetylthio-6-methylenandrost -4-ene-3,17-dione; 4-acetylthio-6-methylene-7α-methylandrost-4-ene- ,17-dione; 4-acetylthio-6-methylene-16α-fluoroandro st-4-ene-3,17-dione; 4-acetylthio-6-methylene-16β-fluoroandrost-4-e e-3,17-dione; 4-acetylthio-6-methylene-7α-methyl-16 α-fluoroandrost-4-ene-3,17-dione; 4-acetylthio-6-methylene-7α-methy -16β-fluoroandrost-4-ene-3,17-dione; 4-acetylthio-6 -methylenandrosta-1,4-diene-3,17-dione; 4-acetylthio-6-methylene-7α methylandrosta-1,4-diene-3,17-dione; 4-acetylthio-6-methylene-16α-fluoroandrosta-1,4-diene-3,17-dione; /DL>4-acethylthio-6-methylene-16β-fluoroandrosta-1,4-di ene-3,17-dione; 4-acetylthio-6-methylene-7α-methyl-16α-fluoroandros a-1,4-diene-3,17-dione; 4-acetylthio-6-methylene-7α -methyl-16β-fluoroandrosta-1,4-diene-3,17-dione; 1-methyl-4-acetylt io-6-methylenandrosta-1,4-diene-3,17-dione; 1,7α-di methyl-4-acetylthio-6-methylenandrosta-1,4-diene-3,17-dione; 1-meth l-4-acetylthio-6-methylene-16α-fluoroandrosta-1,4-diene -3,17-dione; 1-methyl-4-acetylthio-6-methylene-16β-fluoroandrosta-1 4-diene-3,17-dione; 1,7α-dimethyl-4-acetylthio-6-me thylene-16α-fluoroandrosta-1,4-dione-3,17-dione; and 1,7α-dimethyl-4-acetylthio-6-methylene-16β-fluoroandrosta-1,4-d ene-3,17-dione. EXAMPLE X 4-methoxy-6-methylenandrost-4-ene-3,17-dione (I, R = OCH₃, R₁ = R₂ = R₃ = R₄ = H, (x) = single bond) . To a solution of 4-hydroxy-6-methylenandrost-4-ene-3,17-dione (0.315 g, 1 mmole) in benzene (10 ml) potassium tert-butoxide (0.224 g, 2 mmole) is added and the mixture heated to reflux for 30 minutes. After cooling, iodomethane (0.710 g, 5 mmole) is added and the mixture boiled for a further 2 hours. Then the organic solution is washed with water, dried and evaporated in vacuum. Flash column chromatography of the residue on silical gel using n-hexane/ethyl acetate 60:40 affords 0.247 g (75% yield) of the title compound, m.p. 196-198°C. Elemental analysis : Calculated % (found %) C 76.83 (76.40) H 8.59 (8.50) NMR (CDl₃,δ): 0.90 (3H, s) 1.14 (3H, s) 3.60 (3H, s) 5.10 (1H, dd) 5.30 (1H, dd) In analogous fashion and starting from the appropriate 4-hydroxy derivative all the other compounds mentioned in Example V can be prepared. EXAMPLE X1 Tablets each weighing 0.150 g and containing 25 mg of the active substance, can be manufactured as follows: Composition (for 10,000 tablets) 4-methoxy-6-methylenandrost-4-ene-3,17-dione 250g Lactose 800 g Corn starch 415 g Talc powder 30 g Magnesium stearate 5 g The 4-methoxy-6-methylenandrost-4-ene-3,17-dione, the lactose and half the corn starch are mixed; the mixture is then forced through a sieve of 0.5 mm mesh size. Corn starch (10 g) is suspended in warm water (90 ml) and the resulting paste is used to granulate the powder. The granulate is dried, comminuted on a sieve of 1.4 mm mesh size, then the remaining quantity of starch, talc and magnesium stearate is added, carefully mixed and processed into tablets. EXAMPLE XII Capsules, each dosed at 0.200 g and containing 20 mg of the active substance can be prepared with the following composition for 500 capsules: 4-hydro xy-6-methylenandrost-4-ene-3,17-dione 10 g Lactose 80 g Corn starch 5 g Magnesium stearate 5 g This formulation can be encapsulated in two-piece hard gelatin capsules and dosed at 0.200 g for each capsule.

Claims: 1. A compound of formula (I) whereineach of R₁, R₂ and R₃, independently, is hydrogen or C₁-C₆ alkyl; R₄ is hydrogen or fluorine;the symbol ---- indicates that (x) may be either a single bond or a double bond;R is 1) a group -OR₅ wherein R₅ is a) hydrogen; b) C₁-C₆ alkyl; c) a phenyl or benzyl group, each unsubstituted or ring-substituted by one or more substituents chosen from C₁-C₄ alkyl, halogen, trifluoromethyl, nitro, amino, hydroxy and C₁-C₄ alkoxy; d) a group - COR₆ wherein R₆ is (i) a C₁-C₂₂ saturated or C₂-C₂₂ unsaturated aliphatic hydrocarbon radical; (ii) a C₄-C₇ monocycloalkyl group; or (iii) a phenyl or benzyl group, ech unsubstituted or ring substituted as reported above; or e) a hydroxy protecting group; 2) a group - SR₇ wherein R₇ either has one of the meanings (a) to (d) indicated above for R₅ or is a group -SR₈ wherein R₈ is (iv) C₁-C₆ alkyl; (v) a phenyl or benzyl group, each unsubstituted or ring-substituted as reported above; or (vi) a steroidic residue of formula wherein R₁, R₂, R₃, R₄ and (x) are as defined above 3) the group -N₃; or 4) a group wherein each of R₉ and R₁₀, independently, is hydrogen or C₁-C₆ alkyl;and the pharmaceutically acceptable salts thereof. 2. Each compound of formula (I) according to claim 1 wherein each of R₁, R₂ and R₃, independently, is hydrogen or C₁-C₆ alkyl;R₄ is hydrogen or fluorine;(x) represents a single bond or a double bond; andR is a group -OR₅ or a group -SR₇ wherein R₅ or, respectively, R₇ is hydrogen, C₁-C₆ alkyl or a group -COR₆ wherein R₆ is C₁-C₁₇ alkyl. 3. A compound according to claim 2 selected from the group consisiting of:4-hydroxy-6-methylenandrost-4-ene-3,17-dione;4-hydroxy-6-m thylene-7α-methylandrost-4-ene-3,17-dione;4-hydrox y-6-methylene-16α-fluoroandrost-4-ene-3,17-dione;4-hydroxy-6-methy ene-16β-fluorandrost-4-ene-3,17-dione;4-hydroxy-6- methylene-7α-methyl-16α-fluoroandrost-4-ene-3,17-dione;4-hydroxy-6 methylene-7α-methyl-16β-fluoroandrost-4-ene-3,17-dione; 4-methoxy-6-methylandrost-4-ene-3,17-dione;4-methoxy-6-methyl ne-7α-methylandrost -4- ene-3,17-dione;4-methoxy-6-methylene-16α-fluoroandrost-4-ene-3,17- ione;4-methoxy-6-methylene-16β-fluoroandrost-4-ene -3,17-dione;4-methoxy-6-methylene-7α-methyl-16α-fluoroandrost-4-en -3,17-dione;4-methoxy-6-methylene-7α-methyl-16β-fl uoroandrost-4-ene-3,17-dione;4-acetoxy-6-methylenandrost-4-ene-3,1 -dione;4-acetoxy-6-methylene-7α-methylandrost -4- ene-3,17-dione;4-acetoxy-6-methylene-16α-fluoroandrost-4-ene-3,17- ione;4-acetoxy-6-methylene-16β-fluoroandrost-4-ene -3,17-dione;4-acetoxy-6-methylene-7α-methyl-16α-fluoroandrost-4-en -3,17-dione;4-acetoxy-6-methylene-7α-methyl-16β-fl uoroandrost-4-ene-3,17-dione;4-hydroxy-6-methylenandrosta-1,4-dien -3,17-dione;4-hydroxy-6-methylene-7α-methylandrost a-1,4-diene-3,17-dione;4-hydroxy-6-methylene-16α-fluoroandrosta-1, -diene-3,17-dione;4-hydroxy-6-methylene-16β-fluoro androsta-1,4- diene-3,17-dione; 4-hydroxy-6-methylene-7α-methyl-16α-fluoroandrosta-1,4-diene-3,17 dione;4-hydroxy-6-methylene-7α-methyl-16β-fluoroan drosta-1,4-diene-3,17-dione;4-methoxy-6-methylenandrosta-1,4-diene 3,17-dione;4-methoxy-6-methylene-7α-methylandrosta -1,4-diene-3,17-dione;4-methoxy-6-methylene-16α-fluoroandrosta-1,4 diene-3,17-dione;4-methoxy-6-methylene-16β-fluoroa ndrosta-1,4-diene-3,17-dione;4-methoxy-6-methylene-7α-methyl-16α-f uoroandrosta-1,4-diene 3,17-dione;4-methoxy-6-methylene-7α- methyl-16β- fluoroandrosta-1,4-diene-3,17-dione;4-acetoxy-6-methylenandrosta-1 4-diene-3,17-dione;4-acetoxy-6-methylene-7α-methyl androsta-1,4-diene-3,17-dione;4-acetoxy-6-methylene-16α-fluoroandr sta-1,4-diene-3,17-dione;4-acetoxy-6-methylene-16β -fluoroandrosta-1,4-diene-3,17-dione;4-acetoxy-6-methylene-7α-meth l-16α-fluoroandrosta-1,4-diene-3,17-dione;4-acetox y-6-methylene-7α-methyl-16β-fluoroandrosta-1,4-diene-3,17-dione;1- ethyl-4-hydroxy-6-methylenandrosta-1,4-diene-3,17-dione ;1,7α-dimethyl-4-hydroxy-6-methylenandrosta-1,4-diene-3,17-dione;< DL> 1-methyl-4-hydroxy-6-methylene-16α-fluoroandrosta-1, 4-diene-3,17-dione;1-methyl-4-hydroxy-6-methylene-16β-fluoroandros a-1,4-diene-3,17-dione; 1,7α-dimethyl-4-hydroxy-6-methylene-16α-fluoroandrosta-1,4-diene- ,17-dione;1,7α-dimethyl-4-hydroxy-6-methylene-16β- fluoroandrosta-1,4-diene-3,17-dione;1-methyl-4-methoxy-6-metylenan rosta-1,4-diene-3,17-dione;1,7α-dimethyl-4-methoxy -6-methylenandrosta-1,4-diene-3,17-dione;1-methyl-4-methoxy-6-meth lene-16α-fluoroandrosta-1,4-diene-3,17-dione;1-met hyl-4-methoxy-6-methylene-16β-fluoroandrosta-1,4-diene-3,17-dione; ,7α-dimethyl-4-methoxy-6-methylene-16α-fluoroandrosta-1 ,4-diene-3,17-dione;1,7α-dimethyl-4-methoxy-6-methylene-16β-fluoro ndrosta-1,4-diene-3,17-dione;1-methyl-4-acetoxy-6- methylenandrosta-1,4-diene-3,17-dione;1,7α-dimethyl-4-acetoxy-6-me hylenandrosta-1,4-diene-3,17-dione;1-methyl-4-acet oxy-6-methylene-16α-fluoroandrosta-1,4-diene-3,17-dione;1-methyl-4 acetoxy-6-methylene-16β-fluoroandrosta-1,4-diene-3,17-d ione;1,7α-dimethyl-4-acetoxy-6-methylene-16α-fluoroandrosta-1,4-di ne-3,17-dione;1,7α-dimethyl-4-acetoxy-6-methylene- 16β-fluoroandrosta-1,4-diene-3,17-dione;4-mercapto-6-methylenandro t-4-ene-3,17-dione; 4-mercapto-6-methylene-7α-methylandrost-4-ene-3,17-dione;4-m rcapto-6-methylene-16α-fluoroandrost-4-ene-3,17-dione; 4-mercapto-6-methylene-16β-fluoroandrost-4-ene-3,17-dione;4-me capto-6-methylene-7α-methyl-16α-fluoroandrost-4-ene-3,1 7-dione;4-mercapto-6-methylene-7α-methyl-16β-fluoroandrost-4-ene-3 17-dione;4-acetylthio-6-methylenandrost-4-ene-3,17 -dione;4-acetylthio-6-methylene-7α-methylandrost-4-ene-3,17-dione; /DL>4-acetylthio-6-methylene-16α-fluoroandrost-4-ene-3, 17-dione;4-acetylthio-6-methylene-16β-fluoroandrost-4-ene-3,17-dio e;4-acetylthio-6-methylene-7α-methyl-16α-fluoroand rost-4-ene-3,17-dione;4-acetylthio-6-methylene-7α-methyl-16β-fluor androst-4-ene-3,17-dione;4-ethylthio-6-methylenand rost-4-ene-3,17-dione;4-ethylthio-6-methylene-7α-methylandrost-4-e e-3,17-dione;4-ethylthio-6-methylene-16α-fluoroand rost-4-ene-3,17-dione;4-ethylthio-6-methylene-16β-fluoroandrost-4- ne-3,17-dione;4-ethylthio-6-methylene-7α-methyl-16 α-fluoroandrost-4-ene-3,17-dione;4-ethylthio-6-methylene-7α-methyl 16β-fluoroandrost-4-ene-3,17-dione;4-mercapto-6-me thylenandrosta-1,4-diene-3,17-dione;4-mercapto-6-methylene-7α-meth landrosta-1,4-diene-3,17-dione;4-mercapto-6-methyl ene-16α-fluoroandrosta-1,4-diene-3,17-dione; 4-mercapto-6-methylene-16β-fluoroandrosta-1,4-diene-3,17-dione; 4-mercapto-6-methylene-7α-methyl-16α-fluoroandrosta-1,4-diene-3,1 -dione;4-mercapto-6-methylene-7α-methyl-16β-fluoro androsta-1,4-diene-3,17-dione;4-acetylthio-6-methylenandrosta-1,4- iene-3,17-dione;4-acetylthio-6-methylene-7α-methyl androsta - 1,4-diene3,17-dione;4-acetylthio-6-methylene-16α-fluoroandrosta-1, -diene3,17-dione;4-acetylthio-6-methylene-16β-fluo roandrosta-1,4-diene-3,17-dione;4-acetylthio-6-methylene-7α-methyl 16α-fluoroandrosta-1,4-diene-3,17-dione;4-acetylth io-6-methylene-7α-methyl-16β-fluoroandrosta-1,4-diene-3,17-dione;4 ethylthio-6-methylenandrosta-1,4-diene-3,17-dione; 4-ethylthio-6-methylene-7α-methylandrosta-1,4-diene-3,17-dione;4-e hylthio-6-methylene-16α-fluoroandrosta-1,4-diene-3,17-d ione;4-ethylthio-6-methylene-16β-fluoroandrosta-1,4-diene-3,17-dio e;4-ethylthio-6-methylene-7α-methyl-16α-fluoroandr osta-1,4-diene-3,17-dione;4-ethylthio-6-methylene-7α-methyl-16β-fl oroandrosta-1,4-diene-3,17-dione; 1-methyl-4-mercapto-6-methylenandrosta-1,4-diene-3,17-dione; ,7α-dimethyl-4-mercapto-6-methylenandrosta-1,4-diene-3, 17-dione;1-methyl-4-mercapto-6-methylene-16α-fluoroandrosta-1,4-di ne-3,17-dione;1-methyl-4-mercapto-6-methylene-16β- fluoroandrosta-1,4-diene-3,17-dione;1,7α-dimethyl-4-mercapto-6-met ylene-16α-fluoroandrosta-1,4-diene-3,17-dione;1,7α -dimethyl-4-mercapto-6-methylene-16β-fluoroandrosta-1,4-diene-3,17-dion ;1-methyl-4-acetylthio-6-methylenandrosta-1,4-dien e-3,17-dione;1,7α-dimethyl-4-acethylthio-6-methylenandrosta-1,4-di ne-3,17-dione;1-methyl-4-acetylthio-6-methylene-16 α-fluoroandrosta-1,4-diene-3,17-dione;1-methyl-4-acetylthio-6-meth lene-16β-fluoroandrosta-1,4-diene-3,17-dione;1,7α- dimethyl-4-acetylthio-6-methylene-16α-fluoroandrosta-1,4-diene-3,17-dio e;1,7α-dimethyl-4-acetylthio-6-methylene-16β-fluor oandrosta-1,4-diene-3,17-dione1-methyl-4-ethylthio-6-methylenandro ta-1,4-diene-3,17-dione; 1,7α-dimethyl-4-ethylthio-6-methylenandrosta-1,4-diene-3,17-dione 1-methyl-4-ethylthio-6-methylene-16α-fluoroandrost a-1,4-diene-3,17-dione;1-methyl-4-ethylthio-6-methylene-16β-fluoro ndrosta-1,4-diene-3,17-dione;1,7α-dimethyl-4-ethyl thio-6-methylene-16α-fluoroandrosta-1,4-diene-3,17-dione; and1,7α-dimethyl-4-ethylthio-6-methylene-16β-fluoroandrosta-1,4-di ne-3,17-dione. 4. A compound of formula (I) according to claim 1 wherein each of R₁, R₂ and R₃, independently, is hydrogen or C₁-C₆ alkyl;R₄ is hydrogen or fluorine;(x) represents a single bond or a double bond; andR is a group wherein one of R₉ and R₁₀ is hydrogen and the other is hydrogen or C₁-C₆ alkyl;and the pharmaceutically acceptable salts thereof. 5. A compound according to claim 4 selected from the group consisting of:4-amino-6-methylene-7α-methylandrost -4- ene-3,17-dione;4-amino-6-methylene-16α-fluoroandrost-4-ene-3,17-di ne;4-amino-6-methylene-16β-fluoroandrost-4-ene-3,1 7-dione;4-amino-6-methylene-7α-methyl-16α-fluoroandrost-4-ene-3,17 dione;4-amino-6-methylene-7α-methyl-16β-fluoroandr ost-4-ene-3,17-dione; 4-amino-6-methylenandrosta-1,4-diene-3,17-dione;4-amino-6-me hylene-7α-methylandrosta-1,4-diene-3,17-dione;4-am ino-6-methylene-16α-fluoroandrosta-1,4-diene-3,17-dione;4-amino-6- ethylene-16β-fluoroandrosta-1,4-diene-3,17-dione;4 -amino-6-methylene-7α-methyl-16α-fluoroandrosta-1,4-diene-3,17-dione; 4-amino-6-methylene-7α-methyl-16β-fluoroandrosta-1,4- diene-3,17-dione;1-methyl-4-a mino-6-methylenandrosta-1,4-diene-3,17-dione;1,7α-dimethyl-4-amino 6-methylanandrosta-1,4-diene-3,17-dione;1-methyl-4 -amino-6-methylene-16α-fluoroandrosta-1,4-diene-3,17-dione;1-methy -4-amino-6-methylene-16β-fluoroandrosta-1,4-diene-3,17- dione;1,7α-dimethyl-4-amino-6-methylene-16α-fluoroandrosta-1,4-die e-3,17-dione;1,7α-dimethyl-4-amino-6-methylene-16β -fluoroandrosta-1,4-diene-3,17-dione;and the pharmaceutically acceptable salts thereof. 6. A process for the preparation of a compound of formula (I) according to claim 1, or a pharmaceutically acceptable salt thereof, the process comprising: A) treating a compound of formula (II) wherein R₁, R₂, R₃, R₄ and (x) are as defined in claim 1, by solvolysis such as to obtain a compound of formula (I) wherein R is a group -OR₅ wherein R₅ is hydrogen, C₁-C₆ alkyl or phenyl or benzyl group unsubstituted or ring-substituted as defined in claim 1; or B) etherifying a compound of formula (I) wherein R is -OH such as to obtain a compound of formula (I) wherein R is a group -OR₅ wherein R₅ is C₁-C₆ alkyl or a hydroxy protecting group; or C) reacting a compound of formula (II) with a compound of formula (III) R′₇-SH (III)wherein R′₇ is hydrogen, C₁-C₆ alkyl or a phenyl or benzyl group unsubstituted or ring-substituted as indicated in claim 1, so obtaining a compound of formula (I) wherein R is a group -SR₇ wherein R₇ either has one of the meanings reported above for R′₇ or is a group -SR₈ wherein R₈ is a steroidic residue as defined in claim 1 under (vi) in which R₁, R₂, R₃, R₄ and (x) are the same as in the starting compound of formula (II); or D) acylating a compound of formula (I) wherein R is -OH or, respectively -SH, with a reagent carrying a -COR₆ moiety, wherein R₆ is as defined in claim 1, so obtaining a compound of formula (I) wherein R is a group -OR₅ or, respectively, a group -SR₇ wherein R₅ and, respectively, R₇ are a group -COR₆ wherein R₆ is as defined in claim 1; or E) reacting a compound of formula (I) wherein R is -SH with a compound of formula (IV) R₈ - SH (IV)wherein R₈ is a defined in claim 1, so obtaining a compound of formula (I) wherein R is -SR₇ wherein R₇ is a group -SR₈ in which R₈ is as defined in claim 1; or F) reacting a compound of formula (II) with a compound of formula (V) M - N₃ (V) wherein M is an alkali metal or ammonium cation or a tri-C₁-C₆-alkylsilyl group, so obtaining a compound of formula (I) wherein R is the group -N₃; or G) reducing a compound of formula (I) wherein R is the group -N₃, so obtaining a compound of formula (I) wherein R is a group wherein R₉ and R₁₀ are both hydrogen; or H) alkylating a compound of formula (I) wherein R is a group wherein R₉ and R₁₀ are both hydrogen, so obtaining a compound of formula (I) wherein R is a group wherein at least one of R₉ and R₁₀ is C₁-C₆ alkyl;and, if desired,salifying a compound of formula (I) containing a salifiable group or obtaining a free compound from a salt and/or, if desired, separating a mixture of isomers of formula (I) into the single isomers. 7. A pharmaceutical composition comprising a pharmaceutically acceptable carrier and/or diluent and, as active substance, a compound of formula (I) according to claim 1 or a pharmaceutically acceptable salt thereof. 8. A compound of formula (I) or a salt thereof according to claim 1 for use as aromatase inihibitor and in the treatment of hormone-dependent tumors and of prostatic hyperplasia. 9. A pharmaceutical composition according to claim 7 for use as aromatase inhibitor and in the treatment of hormone-dependent tumors and of prostatic hyperplasia. 10.The use of a compound of formula (I) or a salt thereof according to claim 1 in the preparation of a pharmaceutical composition according to claim 7 having activity in inhibiting aromatase and in the treatment of hormone-dependent tumors and prostatic hyperplasia. CLAIMS FOR THE FOLLOWING CONTRACTING STATES: AT, ES AND GR 1. A process for the preparation of a compound of formula (I) whereineach of R₁, R₂ and R₃, independently, is hydrogen or C₁-C₆ alkyl; R₄ is hydrogen or fluorine;the symbol ---- indicates that (x) may be either a single bond or a double bond;R is 1) a group -OR₅ wherein R₅ is a) hydrogen; b) C₁-C₆ alkyl; c) a phenyl or benzyl group, each unsubstituted or ring-substituted by one or more substituents chosen from C₁-C₄ alkyl, halogen, trifluoromethyl, nitro, amino, hydroxy and C₁-C₄ alkoxy; d) a group - COR₆ wherein R₆ is (i) a C₁-C₂₂ saturated or C₂-C₂₂ unsaturated aliphatic hydrocarbon radical; (ii) a C₄-C₇ monocycloalkyl group; or (iii) a phenyl or benzyl group, each unsubstituted or ring substituted as reported above; or e) a hydroxy protecting group; 2) a group - SR₇ wherein R₇ either has one of the meanings (a) to (d) indicated above for R₅ or is a group -SR₈ wherein R₈ is (iv) C₁-C₆ alkyl; (v) a phenyl or benzyl group, each unsubstituted or ring-substituted as reported above; or (vi) a steroidic residue of formula wherein R₁, R₂, R₃, R₄ and (x) are as defined above 3) the group -N₃; or 4) a group wherein each of R₉ and R₁₀, independently, is hydrogen or C₁-C₆ alkyl;or a pharmaceutically acceptable salt thereof, which process comprises: A) treating a compound of formula (II) wherein R₁, R₂, R₃, R₄ and (x) are as defined above, by solvolysis such as to obtain a compound of formula (I) wherein R is a group -OR₅ wherein R₅ is hydrogen, C₁-C₆ alkyl or a phenyl or benzyl group unsubstituted or ring-substituted as defined above; or B) etherifying a compound of formula (I) wherein R is -OH such as to obtain a compound of formula (I) wherein R is a group -OR₅ wherein R₅ is C₁-C₆ alkyl or a hydroxy protecting group; or C) reacting a compound of formula (II) with a compound of formula (III) R′₇-SH (III)wherein R′₇ is hydrogen, C₁-C₆ alkyl or phenyl or benzyl group unsubstituted or ring-substituted as indicated above, so obtaining a compound of formula (I) wherein R is a group -SR₇ wherein R₇ either has one of the meanings reported above for R′₇ or is a group -SR₈ wherein R₈ is a steroidic residue as defined above under (vi) in which R₁, R₂, R₃, R₄ and (x) are the same as in the starting compound of formula (II); or D) acylating a compound of formula (I) wherein R is -OH or, respectively -SH, with a reagent carrying a -COR₆ moiety, wherein R₆ is as defined above, so obtaining a compound of formula (I) wherein R is a group -OR₅ or, respectively, a group -SR₇ wherein R₅ and, respectively, R₇ are a group -COR₆ wherein R₆ is as defined above; or E) reacting a compound of formula (I) wherein R is -SH with a compound of formula (IV) R₈ - SH (IV) wherein R₈ is a defined above, so obtaining a compound of formula (I) wherein R is -SR₇ wherein R₇ is a group -SR₈ in which R₈ is as defined above; or F) reacting a compound of formula (II) with a compound of formula (V) M - N₃ (V)wherein M is an alkali metal or ammonium cation or a tri-C₁-C₆-alkylsilyl group, so obtaining a compound of formula (I) wherein R is the group -N₃; or G) reducing a compound of formula (I) wherein R is the group -N₃, so obtaining a compound of formula (I) wherein R is a group wherein R₉ and R₁₀ are both hydrogen; or H) alkylating a compound of formula (I) wherein R is a group wherein R₉ and R₁₀ are both hydrogen, so obtaining a compound of formula (I) wherein R is a group wherein at least one of R₉ and R₁₀ is C₁-C₆ alkyl;and, if desired, salifying a compound of formula (I) containing a salifiable group or obtaining a free compond from a salt and/or, if desired, separating a mixture of isomers of formula (I) into the single isomers 2. A process according to claim 1, wherein each of R₁, R₂ and R₃, independently, is hydrogen or C₁-C₆ alkyl;R₄ is hydrogen or fluorine;(x) represents a single bond or a double bond; andR is a group -OR₅ or a group -SR₇ wherein R₅ or, respectively, R₇ is hydrogen, C₁-C₆ alkyl or a group -COR₆ wherein R₆ is C₁-C₁₇ alkyl. 3. A process according to claim 1 wherein each of R₁, R₂ and R₃, independently, is hydrogen or C₁-C₆ alkyl;R₄ is hydrogen or fluorine;(x) represents a single bond or a double bond; andR is a group wherein one of R₉ and R₁₀ is hydrogen and the other is hydrogen or C₁-C₆ alkyl.

Inventors: BUZZETTI, FRANCO, COLOMBO, MARISTELLA, DI SALLE, ENRICO, LOMBARDI, PAOLO
Applicants: FARMITALIA CARLO ERBA S.R.L.
Application year: 1987
Main classification: C07J1
IPC codes: A61K31, C07J71, C07J41, A61P35, C07J31, C07J1