Palladium-Catalyzed Oxidative Wacker Cyclizations in Nonpolar Organic Solvents with Molecular Oxygen: A Stepping Stone to Asymmetric Aerobic Cyclizations

A variety of Pd-catalyzed oxidative nucleophile/alkene cyclizations proceeds in excellent yield under simple aerobic conditions in nonpolar media (Pd catalyst, pyridine, and O_2 in toluene). Nucleophiles for these cyclizations include phenols, carboxylic acids, amides, and primary alcohols. Additionally, enantioselective catalysis is feasible with a Pd-sparteine system (see picture). Enantioselectivities of up to 90 % ee are observed for simple phenol/alkene cyclizations