Configuration and conformation of the A-ring of 1-methyl steroids

A detailed NMR analysis of epimeric pairs of 1-methylated steroids in the A/B cis and Δ 4-series has confirmed earlier configurational assignments. One-methyl steroids in the A/B trans series and the 1-methyl hydrocortisone synthesized therefrom are revised from the α to β-configuration. One-β-methyl-5α and 1β-methyl-Δ 4 steroids were judged to be distorted from the normal chair-formed A-ring conformation, the former into the twist and the latter into the alternative half-chair form.