An expedient stereoselective synthesis of (E)-α,β-unsaturated esters and thioesters using FeCl3·6H2O

Abstract

Facile and convenient synthesis of α,β-unsaturated esters and thioesters from alkylidene derivatives of Meldrum’s Acid is described. This method uses catalytic amount of FeCl3·6H2O (0.001–0.005equiv) with alcohols/thiols (1equiv) in dry CH3NO2 followed by catalytic amount of piperidine. A variety of α,β-unsaturated esters and thioesters have been synthesized with high E-stereoselectivity in good to excellent yields. The application of this methodology is demonstrated by gram scale synthesis of octinoxate, a sunscreen agent, and other p-methoxycinnamate esters.