Synthesis of polyhydroxysterols (IV): synthesis of 24-methylene-cholesta-3beta,5alpha,6beta,19-tetrol, a cytotoxic natural hydroxylated sterol.

The cytotoxic, polyhydroxylated sterol 24-methylene-cholesta-3beta,5alpha,6beta,19-tetrol (1), previously isolated from the soft corals Nephthea albida and N. tiexieral verseveldt, was synthesized using stigmasterol as the starting material by 10 steps in 9% overall yield. The spectral data and physical constants of 1 were identical with those of the natural product. This is the first report of the synthesis of 1.