Process for producing vitamin d derivatives

摘要

A process for producing a compound represented by general formula (II) by the reaction of an epoxy compound represented by general formula (I) with an alcohol under a basic condition, wherein R1 represents hydrogen or a protective group; R2 represents hydrogen or hydroxy; R3, R4, R5 and R6 represent such groups that a pair of R3 and R4 and a pair of R5 and R6 form each a double bond, or a pair of R4 and R5 forms a double bond while R3 and R6 are bonded to a dienophile capable of protecting conjugated double bonds; and R7 represents lower alkyl, cycloalkyl or optionally protected lower hydroxyalkyl. This process is one for synthesizing an intermediate of a vitamin D derivative in an imptroved yield without the necessity for complicated procedure of protection and is also suited for mass production.