| abstract |
The invention relates to a process for the preparation of drospirenone starting from 15,16-methylene-androst-4,6-diene-3,17-dione by reaction with a strong base and subsequent reaction with the reaction product of butyllithium and 1-bromopropyl-3 -trimethylsilyl ether to 15,16-methylene-17β-hydroxy-17α- (propyl-3-trimethylsilyloxy) -androst-4,6-dien-3-one, cleavage of the trimethylsilyl protecting group, oxidative ring closure and subsequent methylene addition to drospirenone. Furthermore, the invention relates to a synthesis route from Prasteron drospirenone on the above reaction sequence. |