Method for preparing 17 .alpha.-ester-21-halo pregnanes
申请人:Taisho Pharmaceutical Co., Ltd.
公开号:US04113680A1
公开(公告)日:1978-09-12
One-step method for preparing 17 .alpha.-ester-21-halo pregnanes by reacting 17 .alpha., 21-cyclic orthoesters of 17 .alpha., 21-dihydroxy pregnanes with a halo compound in the presence of an organic polar solvent, simultaneously resulting in halogenation at 21-position and esterification at 17 .alpha.-position of said 17 .alpha., 21-cyclic orthoesters, the reaction proceeding in a short period of time without, or substantially without, any unfavorable side-reactions.