Zinc–acetic acid reduction of the steroid 4-en-3-one: novel conversion of the 4-en-3-one into the 2-en-4-one via a vinyl chloride

Abstract

Transposition of a steroid 4-en-3-one to the 2-en-4-one has been carried out. 4-Chlorotestosterone acetate on Zn–HOAc reduction yields a mixture of the C-5 epimers of the 4-chloro-3-ene together with a C-3 dimer. The vinyl chlorides, after epoxidation followed by rearrangement and elimination, give the 2-en-4-one. A synthesis of 17β-hydroxy-5α-androst-2-en-4-one and 17β-hydroxy-5α-estr-2-en-4-one is described.