Photoinduced transformations. Part 41. Photo-Beckmann rearrangement of some cholestan-3-one oximes with methyl groups attached to the α-carbon

Abstract

Methylation of 4,4-dimethyl-5α-cholestan-3-one with methyl iodide and base gave 2α,4,4-trimethyl-5α-cholestan-3-one and 2,2,4,4-tetramethyl-5α-cholestan-3-one as the major products. The photoreactions of 4,4-dimethyl-5α-cholestan-3-one oxime and 2α,4,4-trimethyl-5α-cholestan-3-one oxime afforded the corresponding 3-aza- and 4-aza-lactams, respectively, arising by a Beckmann-type rearrangement. In these photorearrangements no products resulting from α-fission are formed. These results contrast with those of the acid-catalysed reaction in which products resulting from second-order Beckmann rearrangement predominate.