Preparation of 16.alpha.-methyl steroids

Abstract

A process for the preparation of a compound of the formula ##STR1## in which rings A and B are a remainder: ##STR2## in which the 3-ketone function is optionally protected in the form of a ketal, thioketal, hemithioketal or enol ether, or a remainder: ##STR3## wherein R is methyl or --CH.sub.2 --OR', R' is hydrogen or ether remainder or ester remainder, R.sub.1 and R.sub.2 together form a second bond, or R.sub.1 and R.sub.2 form together an epoxide in beta position, or R.sub.1 is hydrogen, ketone or .alpha.- or .beta.- hydroxy, free or protected in the form of an ether or ester and R.sub.2 is hydrogen, or R.sub.1 is hydrogen and R.sub.2 is .alpha.-hydroxy function, or R.sub.1 is .beta.-hydroxy, free or protected in the form of an ether or ester and R.sub.2 is .alpha.-fluorine or bromine and R.sub.3 is hydrogen or .alpha. or .beta. fluorine or methyl comprising reacting a compound of the formula ##STR4## in which A, B, R, R.sub.1, R.sub.2 and R.sub.3 have the above meaning with a methylation agent in the presence of a copper-based catalyst to form the 16 .alpha.-methylated enolate, hydrolyzing the latter to obtain the corresponding enol and reacting the latter with an oxidizing agent to obtain the compound of formula I.

Dependencies are inferred from the claim text.