Synthesis of (E)-α,β-Unsaturated Esters from 2,2-Dichloroesters and Aldehydes

Significance

Although a vast number of synthetic methods are available for the synthesis of α,β-unsaturated esters from aldehydes, most of them do not offer complete stereoselectivity for the C=C bond formation. Herein, a new interesting protocol for this reaction is presented, which uses 2,2-dichloroesters and active manganese as reducing agent. The process gives exclusively E-isomers, also in the case of α,β-disubstituted acrylates, where the stereocontrol is especially difficult. In many cases, this methodology competes favorably with the conventional Wittig reaction.