Compounds related to provitamin D₃ (II). The sulphur analogue of provitamin D₃

Abstract

Abstract The preparation of the sulphur analogue of provitamin D 3 is described. Bromination of S‐acetyl‐cholestene‐5‐thiol‐3, followed by elimination of hydrogen bromide, did not give good results. The synthesis has been realised by applying these reactions to cholesteryl rhodanide; 7‐dehydrocholesteryl rhodanide so obtained submitted to selective reduction by means of LiAlH 4 afforded cholestadiene‐5,7‐thiol‐3. Bis‐(7‐dehydrocholesteryl‐3)‐disulphide, which may be prepared from 7‐dehydrocholesteryl rhodanide, could also be reduced by means of LiAlH 4 to the same sulphur analogue of provitamin D 3 .