Palladium-Catalyzed [3+2] Cycloaddition of Carbon Dioxide and Trimethylenemethane under Mild Conditions

Carbon dioxide undergoes a Pd-catalyzed [3+2] cycloaddition with trimethylenemethane (TMM) under mild conditions (1 atm, 75 °C, 30 min) to produce a γ-butyrolactone product in 63% yield, when the Pd−TMM complex is generated from 2-(acetoxymethyl)-3-(trimethylsilyl)propene. The reaction reported here is more rapid than the all-carbon [3+2] cycloaddition, and only the γ-butyrolactone is produced in a competition experiment. With substituted substrates, the reaction is completely regioselective, producing the product derived from the kinetic Pd−TMM complex.