PROCESS FOR PREPARING HIGH PURITIY ALLOPREGNANOLONE AND INTERMEDIATES THEREOF

The invention relates to an efficient and industrially applicable process for the preparation and purification of allopregnanolone and intermediates thereof without the assistance of column chromatography. This is done by stereoinversion of the corresponding 3-beta.-OH compound to produce the corresponding 3.alpha.-carboxylic acid ester followed by work-up (precipitation from an organic solvent/water mixture and crystallisation from an apolar organic solvent), followed which may be followed by mild hydrolysis of the ester to produce the free 3.alpha-OH compound allopregnanolone. The post Mitsonobu work-up reduces the level of the 2(3)-ene elimination impurity I and the mild ester hydrolysis minimises the production of the 17.alpha.- epimeric impurity II.