Qua ntum mechanical study on t he mechanism of Le wis acid-catalyzed ene reactions of formaldehyde

Ene re actions are additions of electrophilic double or triple bonds (enophils) to alkenes (enes) with concomitant transfer of an allylic hydrogen ( Eq. (۱)). D espite the synthetic value of Lewis acid-catalyzed ene reactions, a clear mechani stic underst anding of these reactions has been elusive. In his work, we investigated this mechanism using the quantum mechanical appro ach. More specifically, for the rate determining step [۱], being not very clear experimentally, a mechanism was propos ed which is compatible with experim ental evidence.Comp utational details: All o f the presen t calculations have been performed with the B۳LYP [۲] hybrid density functional level using the G۰ ۹ package. The ۶-۳۱۱++G(d,p) basis set was e mployed. The gas phase optimized geometries used to apply the solvent effects, where the valuable PC M [۴] model was employed. We assumed that the change of the molecular geometry upon solvation has a negligible effect on th e thermodynamic parameters. Thu s, the opti mized geometries calculated in gas phase were used. Basically, the o ptimized structures in solvent should be used for frequency calculatio ns, but to reduce computational cost, optimized structures in gas phase could be used as an approximation for this purpose.

کلیدواژه ها:

Mechanism ، Ene reactions ، Density functional theory