Calciferol and its relatives. Part XVIII. Total synthesis of 1 α-hydroxyvitamin D3

Abstract

(3S,5R)-1-Ethynyl-2-methyl-3,5-bistrimethylsilyloxycyclohexene (7), prepared from the optically active lactone 2-methylcyclohexene-3,5-carbolactone (1), was combined with 9α-chloro-des-AB-cholestan-8-one {5α-chloro-1β-[(1R)-1,5-dimethylhexyl]-7aβ-methyl-trans-perhydroindan-4-one}(8) to give the chlorohydrin (9), from which, in turn, 1α-hydroxyprecalciferol₃ diacetate (11), and 1α-hydroxyvitamin D₃(12; R = H) were obtained.