METHOD FOR PREPARING 17A-ESTER 21-HALO PREGNANES

摘要

A method for preparing 17.alpha.-ester-21-halo pregnanes, which comprises reacting 17.alpha.,21-cyclic orthoesters of 17.alpha.,21-dihydroxy pregnanes with a halo compound in the presence of an organic polar solvent, enables the simultaneous halogenation at 21 position and esterification at 17.alpha.-position of said 17.alpha.,21-cyclic orthoesters to proceed at one step in a short time without any unfavorable side-reactions.