Starting from stigmasterol (2), 24-methylenecholest-4-en-3β, 6β-diol (1), a cytotoxic natural dihydroxylated sterol, was synthesized via 10 steps in 20% overall yield. The introduction of a side-chain of sterol was achieved by solid-liquid phase-transfer Wittig reaction using (3- methyl-2-oxo) butyltriphenylarsonium bromide (12) and K2CO3. Construction of the steroidal nucleus was finished by the addition of 3β-acetoxycholest-5, 6-en-24-one (7) with NBA in ...