Photoinduced molecular transformations. Part 126. Photo-double ring contraction of 4a-homo-5α-cholest-3-en-1-one, a steroidal β,γ-unsaturated cyclic ketone, involving photochemical 1,3-acyl migration

Abstract

Both direct and sensitized irradiation of 4a-homo-5α-cholest-3-en-l -one in tert-butyl alcohol with Pyrex-filtered light resulted in a photorearrangement to 1α-vinyl-3,4-bisnor-5α,10α-cholestane via a photochemical 1,3-acyl shift, followed by a photochemical loss of carbon monoxide from the resulting 2α-vinyl-4-nor-5α-cholestan-1-one.