Solvent effects on the asymmetric Diels-Alder reaction between cyclopentadiene and (-)-menthyl acrylate revisited with the three-layer hybrid local self-consistent field/molecular mechanics/self-consistent reaction field method

The construction of the three-layer hybrid local self-consistent field/molecular mechanics/self-consistent reaction field method is detailed. This method is specifically devoted to the study of the reactivity of large chemical systems in solution. The solvent, modeled by a polarizable continuum, surrounds the whole solute molecule. Solute-solvent interactions are taken into account by means of the self-consistent reaction field approach. The solute system is treated by both quantum and molecular mechanics, the former being principally applied to the reactive part, i.e., the part undertaking bond forming or breaking, the latter being reserved for the ancillary encumbering groups. The connection between the molecular mechanics and the quantum mechanics part is accomplished by a strictly localized bond orbital that remains frozen within the local self-consistent field framework. As a test system, the asymmetric Diels-Alder reaction between cyclopentadiene and (-)-menthyl acrylate is studied for the first time with steric interactions and electrostatic solvent effects taken into account simultaneously. The results indicate that the coupling of both interactions leads to conclusions that could not have been guessed from separate calculations.