A practical, efficient, and atom economic alternative to the Wittig and Horner-Wadsworth-Emmons reactions for the synthesis of (E)-α,β- unsaturated esters from aldehydes

We describe a highly efficient new methodology for the synthesis of (E)-α,β-unsaturated esters from aldehydes. In our DMAP-catalyzed reaction, both aromatic as well as aliphatic aldehydes furnish the desired products highly regio- and stereoselectively if treated with commercially available or synthetically easily accessible malonic acid half ester. A large scale application in the synthesis of p-methoxycinnamates, which are of use as sunscreen ingredients, is described.