Novel vitamin D3 analogues.

摘要

Vitamin D3 analogues of the formula: wherein R<1> is hydrogen atom and R<2> is hydroxy, or R<1> is hydroxy and R<2> is hydrogen atom, X is hydrogen atom, hydroxy or a hydroxy protected by a hydroxy-protecting group, and R<3> is hydrogen atom or a hydroxy-protecting group, which have vitamin D3-like activities such as activity of controlling calcium metabolism and tumor cell differentiation-inducing activity.