Some transformations of 6α-Bromocholest-4-en-3β-ol and its 3-Acetate. A convenient synthesis of 3,6-Dialkoxysteroids

Abstract

The term "ambiallylic" is introduced to describe the system -C-C=C-C- in which X and Y are functional groups. The novel reactivity of some ambiallylic systems, including 6a-bromocholest-4-en-3β-ol and its 3-acetate, is discussed. During chromatography over Florisil 6α-bromocholest-4-en-3β-ol was con- verted to a mixture of cholest-4-en-3-one, cholest-5-en-3-one, and cholest-4-ene- 3β,6β-diol, together with other unidentified products. Chromatography of 6α-bromo- cholest-4-en-3β-ol 3-acetate over Florisil led to extensive decomposition; the only product identified was cholest-5-ene-3β,4β-diol 4-acetate. Treatment of 6α-bromocholest-4-en-3β-ol 3-acetate with methanol or ethanol containing pyridine gave 6α-methoxy- or 6β-ethoxy-cholest-4-en-3β-ol 3-acetate, which upon further reaction with methanol or ethanol containing hydrochloric acid afforded 3β,6β-dimethoxy-, 3β-ethoxy-6β-methoxy-, 3β-methoxy-6β-ethoxy-, or 3β,6β-diethoxy-cholest-4-ene, respectively.