The aldol stage of the Perkin reaction

Abstract

The interaction of benzaldehyde, phenylacetic acid, acetic anhydride, and triethylamine at room temperature leads to a mixture of α-phenyl-trans-cinnamic acid and the diastereomeric 3-acetoxy-2,3-diphenylpropionic acids. At –24° the acetoxy-acids are the main product, with the erythro-isomer predominant. No isomerisation could be detected under the conditions used. Some suggestions have been made with regard to the mechanism of the aldol stage of the Perkin reaction.