Steroids. Part XII. Westphalen-type rearrangements of 5α-hydroxy-4α-methyl- and 5α-hydroxy-4β-methyl-steroids

Abstract

Westphalen-type rearrangements of the 6α- and 6β-acetoxy-5α-hydroxy-4β-methyl compounds (10) and (7), the 5α-hydroxy-4β-methyl-6-oxo-compound (8), and the 6β-acetoxy-5α-hydroxy-4α-methyl compound (14) are reported. The 6α-acetoxy-5α-hydroxy-4α-methyl compound (12) is dehydrated to give the Δ⁴-compound (27), and the 5α-hydroxy-4α-methyl-6-oxo-compound (15) gives the 5α-acetate (29) and the Δ⁴-compound (28). These results and rate data for the reactions of compounds (10) and (14) suggest the possibility of the rearrangement proceeding with a synchronous methyl migration and C(5)–O cleavage.