A DFT study on palladium-catalyzed decarboxylative intramolecular aziridination reaction mechanism

The mechanism of palladium-catalyzed intramolecular decarboxylative aziridination reaction from 4H-isoxazol-5-one leading to 1-azabicyclo[3.1.0]hex-2-ene has been studied computationally with the aid of density functional theory (DFT). Full free energy profiles are computed for different reaction pathways. The catalytic cycle was found to include four steps: oxidative addition, decarboxylation, olefin insertion and reductive elimination. The DFT calculations indicated that the decarboxylation is the rate-determining step for palladium-catalyzed intramolecular decarboxylative aziridination reaction with an overall barrier of 32.9 kcal/mol from intermediate 4 to transition state TS6, which is in well agreement with previous calculations on palladium-catalyzed decarboxylative coupling reactions.