Patent ID: 8841283

Claim:
Process for the preparation of 6β,7β,15β,16β-dimethylen-3-oxo-17α-pregn-4-ene-21,17-carbolactone (Drospirenone, 5) from a compound of formula 2 wherein R is a hydroxyl protective group selected from the group consisting of a silyl derivative Q 3 Si—, wherein each Q, independently from one another, represents (C 1 -C 6 )alkyl, (C 6 -C 10 )aryl, (C 1 -C 4 )alkylaryl or (C 1 -C 4 )alkoxyaryl, said process comprising the following sequential steps a)-c): a) removing the hydroxyl protective group of the compound of formula 2 to give compound 17α-(3-hydroxypropyl)-6β,7β,15β,16β-dimethylen-5β-androstane-3β,5,17β-triol of formula 3 b) reacting the compound of formula 3 with an oxidizing agent selected from 1,3,5-trichloro-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione (TCCA) in the presence of a base or with 1-hydroxy-1,2-benziodoxol-3(1H)-one 1-oxide (IBX) to give a compound of formula 4 c) eliminating water from positions C4-C5 of the compound 4, whereby Drospirenone 5 is obtained; or the following sequential steps a′)-b′): a′) removing the hydroxyl protective group of the compound of formula 2 as above defined to give the 17α-(3-hydroxypropyl)-6β,7β,15β,16β-dimethylen-5β-androstane-3β,5,17β-triol of formula 3 b′) reacting the compound of formula 3 with the oxidizing agent 1,3-dichloro-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione (DCCA), or an alkaline metal salt thereof, in the presence of an acid with concomitant elimination of water from the positions C4-C5 to afford Drospirenone 5; or the following sequential steps a″)-d″): a″) reacting a compound of formula 2 with an oxidizing agent selected from TCCA or IBX to give a compound of formula 6 wherein R is selected from the group consisting of a silyl derivative Q 3 Si—, wherein each Q, independently from one another, represents (C 1 -C 6 )alkyl, (C 6 -C 10 )aryl, (C 1 -C 4 )alkylaryl or (C 1 -C 4 )alkoxyaryl; b″) removing the hydroxyl protective group from the compound obtained in step a″), whereby compound 7 is obtained c″) reacting compound 7 with an oxidizing agent selected from TCCA or IBX to give the compound of formula 4 d″) eliminating water from the positions C4-C5 of compound 4, whereby Drospirenone 5 is obtained.