Diels-alder reactions of 2-azabutadienes with aldehydes: ab inition and density functional theoretical study of the reaction mechanism, regioselectivity, acid catalysis, and stereoselectivity

摘要

The Diels-Alder reaction of 2-azabutadiene with aldehydes has been studied using high level ab inition molecular orbital and density functional methods. Multiconfigurational calculations were carried out on the concerted and stepwise mechanisms. At the CASPT2F/6-31G*//CASSCF/6-31G* level of theory, the [π4s+π2s]-cycladdition of 2-azabutadiene with formaldehyde is predicted to be a concerted reaction, in good agreement with the experimental evidence.