The Photo-Beckmann Rearrangement of 3α,5-Cyclo-5α-cholestan-6-one Oxime

Abstract Photolysis of 3α,5-cyclo-5α-cholestan-6-one oxime affords two isomeric lactams with cyclopropane rings arising from photo-Beckmann rearrangement although the yields are poor. The result gives further support to our view on the C→N migration process in photo-Beckmann rearrangement. The major part of the products of the reaction consisted of the parent ketone and several products probably derived from it. The results are compared with those obtained in our photolysis of 5α-cholestan-6-one oxime and the isomeric 5β-cholestan-6-one oximes. The poor yields of the lactams is probably ascribable to the presence of the cyclopropane ring in this conjugated cyclopropyl ketone oxime.