Cyclisation of unsaturated bases derived by Hofmann degradation of perhydroazepines: a convenient synthesis of aza-steroids from steroidal ketoximes

Abstract

The steroidal perhydroazepines obtained by reduction of the Beckmann rearrangement products of cyclic ketoximes of the 5α-cholestane series yielded methine bases on Hofmann degradation. In most cases these unsaturated bases were cyclised in boiling acetic acid to give quaternary salts which are derivatives of aza-steroids containing 2-methylpiperidine residues.