Concise and stereoselective synthesis of (+/-)-Hagen's gland lactone

Abstract

The synthesis of (+/-)-Hagen's gland lactone 1 has been completed in three steps in 44% from commercially available starting materials. The work is highlighted by a straightforward preparation of butenolide through an epoxide opening using 2-lithiofuran and a concise and stereoselective synthesis of furano-gamma-lactone by a novel DBU-promoted sequential isomerization/intramolecular oxa-Michael addition of a hydroxybutenolide.