Regeneration of a Steroid C13 Angular Methyl Group from a Functionalized Precursor : Application to the Preparation of C 18-²H₃ Steroids and C 18-²H₃ D-Homosteroids

Abstract

3β-Acetoxypregn-5-eno-18,20-lactone has been converted into 3β,20β-dimethoxypregn-5-ene (6) by using electrochemical deoxygenation of a C13 formyl intermediate as a key reaction. The electrochemicalreduction is also shown to be applicable to multiple deuterium labelling of the C13 angular methyl group in high isotopic purity.A facile preparation of 3β -hydroxy-17α-methyl-D-homoandrost-5-en-17a-one (10) and its respective C18-²H₃ analogue from the ether (6) is described.