Dihydropyran as a Template for Lactone Synthesis

Abstract

3,4‐Dihydro‐2H‐pyran (DHP) was efficiently transformed into 4‐thiophenyl‐3,4‐dihydro‐2H‐pyran. This intermediate was converted to the corresponding 1,3‐O,S‐allylic carbanion with t‐butyllithium and selectively alkylated at the carbon α to the sulfur with alkyl halides, an epoxide, and an aldehyde. An one‐pot oxidative elimination of the sulfur fragment using vanadium pentoxide generates the desired β‐substituted α,β‐unsaturated δ‐valero lactone.