Friedel–Crafts alkylation of benzene with α,β-unsaturated amides

A variety of α,β-unsaturated amides (RHCCH2CONR′2, R=H, Me, Ar; R′=H or Et) readily condense with benzene at room temperature in the presence of an excess of aluminum chloride to give the corresponding 3-phenylpropionamides in excellent yields. This simple, one-pot procedure proved to be efficient and very clean. The mechanism of these and related reactions is discussed and the participation of superelectrophilic dicationic intermediates is suggested.