new method for the preparation of 20 - keto hydroxysterou00efden 21alfa - and intermediate acting.

摘要

The invention relates to a new process for the preparation of compounds (I): IMAGE where R1 is alkyl (1-3c), R2 is alkyl (1-12c) and R3 is alkyl (1-4c), starting with the corresponding derivative 17 beta -CN 17 alpha -OR4, where R4 is an easily cleavable ether residue, as well as intermediates. Compounds (I) are known and described in European Patent No. 7823.