Calciferol and its relatives. Part 24. A synthesis of vitamin D4

Abstract
8α-Phenylsulphonyl-des-AB-ergostane (16), prepared from des-AB-ergost-8-ene, formed a lithium derivative which reacted with the benzoyloxy-aldehyde (8) to give, after treatment with trimethylchlorosilane, a mixture of β-silyloxy-sulphones. Reduction with lithium amalgam, followed by removal of the benzoyl group, gave vitamin D4(2).