Process for preparing vitamin D3 derivatives.

摘要

Prepn. of specific epimers of 1-alpha,25,26-trihydroxy-22-ene -cholecalciferol (I) comprises (a) reacting a ylide cpd. of formula (II) with an epoxide cpd. of formula (III) to give a phosphine cpd. of formula (IV), (b) reacting (IV) with a specific epimer of an aldehyde of formula (V) to give a specific epimer of a cpd. of formula (VI), (c) reacting (VI) to give a specific epimer of formula (VII) and (d) isomerising (VII) to give a specific epimer of formula (I), X = a hydroxy protecting gp., Y = a silyl-contg. hydroxy protecting gp.