Ireland-Claisen rearrangement of steroidal triangle open~(23)-22-alcohols: an application to triangle open~(22,25)-24-alkyl steroid synthesis

摘要

A new method for the preparation of a 1,4-diene system in the steroid side chain, providing the possibility of stereocontrol at C-3 has been described. Its usefulness has been examined for triangle open~(22,25)-24-alkyl steroid synthesis. The proposed approach is based on the Ireland-Claisen rearrangement of griagle open~(23)-22-alcohols followed by C-25 silylation of the formed ester and Peterson olefination as the final step.