A novel aromatisation reaction of 11-oxolanostanes

Abstract

Oxidation of 11-oxolanostan-3β-yl acetate (1a) with selenium dioxide in acetic acid is accompanied by a C-nor-D-homo rearrangement of the steroid skeleton with aromatisation of ring D and formation of 9β-hydroxy-4,4,15-trimethyl-11-oxo-14(13→12)abeo-5α-cholesta-12,14,16-trien-3β-yl acetate (2a). Analogous aromatic products are obtained from 3β,7α- and 3β,7β-diacetoxy-11-oxolanostanes (1b and c), respectively, methyl 3β-acetoxy-11-oxo-25,26,27-trinorlanostan-24-oate (1e) and methyl 3β-acetoxy-24-methyl-11-oxolanostan-21-oate (1f), under the same conditions.