Abstract Aromatic aldehydes react with triphenylphosphine and ethyl trichloroacetate or trichloroacetonitrile to give the corresponding benzylidene dichlorides or α-chlorocinnamic acid derivatives. The chemo-and regioselectivity of these reactions depend on both the substituent in the aromatic ring and reaction conditions. The product configuration was determined on the basis of the coupling constants 2 J CH and 3 J CH in the 13 C NMR ...