An β-Aroylacrylic acid ethyl ester such as ethyl (E)-4-(3, 4-dimethoxyphenyl)-4-oxo-2- butenoate (1) can be obtained in good yield and with excellent purity by way of the Friedel– Crafts reaction in which 1, 2-dimethoxybenzene (2) is treated with maleic anhydride (3) and aluminum chloride in the presence of diethyl sulfate (4) under mild conditions.
