Combined quantum chemical and MM-approach to the endo/exo selectivity of diels-alder reactions in polar media

Abstract

The endo/exo selectivity of Diels-Alder reactions in water and methanol is studied with semiempirical methods using the SCRF approach and a combined quantum chemical (transition state) and molecular mechanics (solvent molecules) method (QC/MM) to determine the effect of protic solvents on the transition state energies. Evidently, the number of hydrogen bonds that causes strong Coulomb interaction, discriminates heats of formation of transition states. The results indicate that the s-cis/s-trans conformation of acrylates controls the endo/exo selectivity.