GB773150A - Improvements in or relating to the preparation of steroid compounds - Google Patents

Abstract

3b ,12b - Dihydroxy - 11 - oxo - 23 - bromo-5a , 22a-spirostan is prepared by hydrolysing an 11,23-dibromo-hecogenin ester with caustic alkali in solution in aqueous tertiary butanol or aqueous dioxan. The caustic alkali is preferably sodium or potassium hydroxide, a suitable concentration of caustic alkali being between 0.5 and 15 per cent by weight, preferably between 2.5 and 10 per cent by weight, of the reaction mixture. The hydrolysis may be carried out at a temperature between 70 DEG C. and the boiling point of the solvent used. The above process may be modified in that the 11,23-dibromo-hecogenin ester is prepared by dibrominating hecogenin ester at the 11- and 23-positions in solution in dioxan, and aqueous caustic alkali is then added to the reaction mixture to carry out the desired hydrolysis to form 3b ,12b - dihydroxy - 11 - oxo - 23 - bromo-5a ,22a-spirostan. The 11,23-dibromohecogenin ester or hecogenin ester used in the above process may be the acetate. The above processes may be extended to prepare diesters of 3b ,12b - dihydroxy - 11 - oxo - 5a ,22a - spirostan by esterifying the 3b ,12b -dihydroxy-11-oxo-23-bromo-5a ,22a-spirostan, e.g. by heating with acetic anhydride and pyridine, and the product is debrominated by treatment with zinc and acetic acid. A number of detailed examples are given illustrating the above processes, in addition 3b ,12b - dihydroxy - 11 - oxo - 23 - bromo-5a ,22a-spirostan is debrominated with zinc and acetic acid and is then acetylated to form 3b -12b - diacetoxy - 11 - oxo - 5a ,22a - spirostan. Reference has been directed by the Comptroller to Specification 721,953.