A flexible route for the stereoselective synthesis of trisubstituted γ-butyrolactones,
namely (+)-blastomycinone and its analogs, is devised by the Sharpless asymmetric
epoxidation and the regioselective ring opening reaction with dibutylcopper lithium
as the key steps to introduce the requisite alkyl chain.
(+)-blastomycinone - (-)-3-epi-blastomycinone - Sharpless asymmetric epoxidation - dibutylcopper lithium - Wittig
olefination