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 O2 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.