Vitamin D3 derivative and production process thereof

摘要

A vitamin D3 derivative represented by the following formula: wherein, R is, independently, a hydrogen atom, tri(C1 to C7 hydrocarbon)silyl group, C2 to C8 acyl group, or group forming an acetal bond together with an oxygen atom of a hydroxyl group, A is where, R<1> is a methyl group or methylene group, and when R<1> is a methylene group, the bond between the R<1> and the 3-position of the lactone ring is a double bond, R<2> is a hydrogen atom or C1 to C3 alkyl group, R<3> is a hydrogen atom, or R<2> and R<3> together indicate a substitutable single methylene group.