Alkylated steroids. Part 2. 16α,17α-Dimethylpregnanes functionalised in ring C
Abstract
An improved process for the preparation of 16α,17α-dimethylpregnanes (1b)–(9b) from pregn-16-en-20-ones has been developed and applied to ring C functionalised steroids (1a)–(9a) as a route to corticosteroid analogues. Good to excellent yields of the 16α,17α-dimethyl derivatives were achieved in all cases except with 11β-hydroxy-compounds and this was overcome by using the acetate. Two by-products, formed in variable amounts, were the 16α-methyl and 16α,17α,21-trimethyl derivatives (c) and (d) respectively.