Palladium(II)-Catalyzed Aerobic Intermolecular Cyclization of Acrylic Acid with Alkenes to α-Methylene-γ-butyrolactones

The methodology in this article is a palladium(II)/copper(II)- or palladium(II)-catalyzed intermolecular cyclization of acrylic acid with alkenes to produce α-methylene-γ-butyrolactone derivatives using molecular oxygen as an environmentally benign oxidant. In this system, the carboxylato, especially trifluoroacetato, or trimethylacetato ligand, plays a quite important role to afford a high catalytic activity by suppressing the deposition of palladium(0) black.