Photo-induced transformations. Part LXI. Syntheses of some six-membered and eight-membered lactams of the B-homo- and A-nor-B,B-dihomocholestane series by the photo-Beckmann rearrangement

Abstract

The syntheses of 3-aza-B-homo-5α-cholestan-4-one, 4-aza-B-homo-5α-cholestan-3-one, 6-aza-A-nor-B,B-dihomo-5α- and 5β-cholestan-7-one, and 7-aza-A-nor-B,B-dihomo-5α- and 5β-cholestan-6-one by the photo-Beckmann rearrangement of the oximes of A-nor-B-homo-5α-cholestan-3-one and A-nor-B-homo-5α and 5β-cholestan-6-one are described. An A/Btrans ring-junction stereochemistry of the parent ketones was deduced by estimating the relative stabilities of the principal conformers of the A/Bcis- and trans-isomers of the A-nor-B-homocholestan-3-ones and A-nor-B-homocholestan-6-ones by molecular mechanics calculations.