NEW PROCESS FOR PRODUCING 17-BETHA-HYDROXY-17-ALPHA-METHYL-2-OXA-5-ALPHA-ANDROSTAN-3-ON, AS WELL AS INTERMEDIATE THEREOF

The invention relates to a new process for the synthesis of 17beta-hydroxy-17alpha-methyl-2-oxa-5alpha-androstane-3-one of formula (I). The process according to the invention is as follows: the 17beta-hydroxy-17alpha-ethyl-1,3-seco-2-nor-5alpha-androstane-1,3-diacid of formula (III) is transformed into the ring-closed 17beta-hydroxy-17alpha-methyl-1,3-seco-2-nor-5alpha-androstane-1,3-diacid anhydride of formula (II) in an inert solvent or without solvent with a C2-C3 alkan acid anhydride or a substituted carbodiimide of formula R1-N=C=N-R2- wherein R1 and R2 independently are C1-C6 alkyl group, C1-C6 alkyl group substituted by tertiary or quaternary amino group or 1-3 phenyl group, C5-C6 cycloalkyl group, aryl group substituted by 1-3 methoxy, tertiary amino, nitro, C1-C4 alkyl group or 1-3 halogen atom-and the obtained compound of formula (II) is reduced regioselectively by a complex alkali metal hydride in an inert solvent The new 17beta-hydroxy-17alpha-methyl-1,3-seco-2-nor-5alpha-androstane-1,3-diacid anhydride of formula (II) is also the subject of the invention.