GB737701A - Steroid ketals - Google Patents

Abstract

The invention comprises a 17a -hydroxypregnane - 1,20 - dione 20 - ketal having the general formula <FORM:0737701/IV (b)/1> wherein R1 is hydrogen or an acyl radical of an unsubstituted monocarboxylic hydrocarbon acid containing from one to eight carbon atoms, inclusive, and wherein R is hydrogen or a lower alkyl radical containing from one to six carbon atoms and n is 1 or 2, and the preparation thereof by mixing together an alkane-1,2-diol or alkane-1,3-diol containing from two to eight carbon atoms inclusive, e.g. ethylene glycol, propane-1,2-diol, propane-1,3-diol, butane-1,2-diol, pentane-1,2-diol, 3-methylpentane-1,2-diol, hexane-1,3 - diol or octane - 1,2 - diol, and a 3-acyloxy or hydroxy - 17a - hydroxypregnane-11,20-dione in the presence of an acid catalyst, e.g. m- and p-toluene sulphonic acids, naphthalenesulphonic acid, benzenesulphonic acid, o-chlorobenzenesulphonic acid, hydrochloric acid and sulphuric acid. The reaction may be effected in an organic solvent between 20 DEG and 200 DEG C. In examples R1 is hydrogen, acetyl and benzoyl. 3b - Acetoxy - 17a - hydroxypregnane - 11,20-dione is obtained by acetylating 3b -hydroxypregnane-11,20-dione, treating the 3b -acetate thus formed with acetic anhydride in the presence of p-toluene sulphonic acid to produce 3a ,11,20-triacetoxy-9(11), 17(20)-pregnadiene, the enol acetate of which is epoxidized at the 17(20-position with peracetic acid and the resulting epoxide is saponified with sodium hydroxide to produce 3b ,17a -dihydroxypregnane-11,20-dione, followed by acetylation.