Synthesis of 3,4-disubstituted α-methylene-γ-lactones via sonochemical Barbier-type reaction

A series of 3,4-disubstituted α-methylene-γ-lactones were synthesized by the addition reaction of allylic bromide with aldehyde via sonochemical Barbier-type reaction condition and then followed by the in situ intramolecular esterification. The α-methylene-γ-lactone was produced as the sole product when THF/PhH solvent mixture was used whereas the allylation adduct was generated as the major product when solvent DMF was used.