Ireland–Claisen rearrangement of steroidal Δ23-22-alcohols: an application to Δ22,25-24-alkyl steroid synthesis

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 Δ22,25-24-alkyl steroid synthesis. The proposed approach is based on the Ireland–Claisen rearrangement of Δ23-22-alcohols followed by C-25 silylation of the formed ester and Peterson olefination as the final step.