Intermediates in the synthesis of vitamin D derivatives.

摘要

Compounds of the general formula
wherein R represents a hydrogen atom or a hydroxyl protecting group, Y represents a hydrogen atom or an optionally protected hydroxyl group, X represents the residue of a dienophile and either R¹ represents a halogen atom a hydrocarbylsulphonyloxy group or a group of the formula -Z-R³ (in which Z represents -O-, -S-, -SO-, -NR^4- or -CR⁴R⁵- and R³, R⁴ and R⁵, which may be the same or different, each represent a hydrogen atom or a straight or branched aliphatic group having 1-12 carbon atoms and which may optionally carry one or more substituents) and R² represents a hydrogen atom or R¹ and R² together represent an oxo group or an optionally substituted alkylidene group, except that R¹ and R² together with the group -CH(CH₃)CH- to which they are attached do not represent a group having the branched 17p-hydrocarbyl side chain skeleton of vitamin D₂ or vitamin D₃ of use in the preparation of novel vitamin D analogues.