Theoretical Study of the Mechanism of Palladium-Catalyzed Arylation of Alkenyl Carboxylates

Palladium-catalyzed cross-coupling of an organometallic nucleophile is one of the most important C-C bond forming methods in almost all areas of synthetic chemistry. We investigate the potential energy surfaces of the Pd-catalyzed arylation of alkenyl carboxylates using density functional theory and try to elucidate their mechanisms. The reactions involving Pd(0)/(II) and only Pd(0) are studied in detail. The results show that these two kinds of reactions have feasible reaction pathways under mild condition. The most feasible reaction channels are Pathways A and C through a three-membered ring transition state with the highest energy barriers of 21.4 kcal/mol relative to the reactant, indicating that they can occur even at room temperature. When C6H5 free radical is produced, the energy barrier of Pathway B is the highest with a value of 33.5 kcal/mol relative to the reactant, which can occur under the experimental condition with a temperature of 60 degrees C.