An aromatization reaction of a 13α-methyl steroid

Abstract

Whilst treatment of 6β,7β-dihydroxy-3α,5α-cycloandrostan-17-one with hydrogen bromide in glacial acetic acid affords, inter alia, the 13β,14β-cis-C/D-fused anthrasteroid, the corresponding 13α-methyl epimer affords the enantiomeric 13α,14α-anthrasteroid without isomerization at C-14. The stereochemistry of the anthrasteroid was established by n.o.e. measurements. Repetition using deuterium bromide led to extensive deuteriation. The major aromatic steroid that was formed in each case was an estratriene.