Synthesis of cis-3,4-diaryl α-methylene-γ-butyrolactams via sonochemical Barbier-type reaction

A series of cis-3,4-diaryl α-methylene-γ-butyrolactams were synthesized by the addition reaction of 3-phenylallyl bromide with N-tosyl aldimine via sonochemical Barbier-type reaction condition and then followed by the in situ intramolecular amidation. The cis-3,4-diaryl α-methylene-γ-butyrolactam was obtained as the sole regio- and stereoisomeric product when N-tosyl aldimine was used as the substrate whereas the monoaryl α-methylene-γ-butyrolactam was also generated when N-phenyl aldimine was used.