Calculated linear free energy relationships in the course of the Suzuki-Miyaura coupling reaction

Concerning the Suzuki-Miyaura coupling reaction, we report detailed theoretical study of thermodynamic data (at the B3PW91/LANL2DZ level with polarization functions added and including dispersion force corrections) concerning each step of the catalytic cycle. In each case, we have observed a Hammett plotting of delta E or delta G versus sigma(p) of substituent of various reagents, which accounts for multiple-substituent effects. Therefore, these calculations predict the influence of the electron-donor/electron-acceptor character of each substituents on the thermodynamic requirements for reaction. Our major conclusion is that the transmetalation between a palladium hydroxo complex and an arylboronic acid is preferable to the transmetalation with a palladium bromo complex. Moreover, the alkaline hydrolysis of palladium bromo complex appears as a strong exothermic reaction. Concerning the reductive elimination step alternative processes have been investigated. The overall process giving rise to biphenyls appears as a very strong exothermic reaction (similar to-110 kcal/mol in ideal gas; similar to-95 kcal/mol using water as solvent). (c) 2014 Elsevier Ltd. All rights reserved.