(22E)-5,7,22-Ergostatriene-1.alpha.,3.beta.,25-triol and the 24-epimer thereof which are new intermediates for the synthesis of 1.alpha.,25-dihydroxyvitamin D.sub.2 and the 24-epimer thereof. A new process for the preparation of 1.alpha.,25-dihydroxyvitamin D.sub.2 and the 24-epimer thereof is also described which comprises irradiation of (22E)-5,7,22-ergostatriene-1.alpha.,3.beta.,25-triol or the 24-epimer thereof followed by isomerization.
(22E)-5,7,22-Ergostatriene-1.alpha.,3.beta.,25-triol及其24-表异构体是合成1.alpha.,25-二羟基
维生素D.sub.2及其24-表异构体的新中间体。还描述了一种制备1.alpha.,25-二羟基
维生素D.sub.2及其24-表异构体的新工艺,该工艺包括对(22E)-5,7,22-ergostatriene-1.alpha.,3.beta.,25-triol或其24-表异构体进行辐照,然后进行异构化。