Synthesis of E- and Z-o-Methoxy-Substituted 2,3-Diphenyl Propenoic Acids and Its Methyl Esters

A series of stereoisomeric o-methoxy-substituted 2,3-diphenyl propenoic acids and their methyl esters have been synthesized. The E isomers were prepared by a modified Perkin condensation (substituted benzaldehyde, phenylacetic acid, Et3N/acetic anhydride). The difficult to access Z isomers were obtained conveniently in good yields when the appropriate coumarin derivatives were allowed to react with KOH and CH3I in DMSO.