The influence of non-covalent interaction of PHCl2 on the activation energy of Aza-Diels-Alder Reaction

Using DFT calculations, the combination of X2C=NNH2 (X= F, Cl, Br) and 1,3-butadiene to form asix-membered was investigated. At first, the effect of various substituents of X2C=NNH2 (X= F, Cl, Br) and then theeffect of non-covalent interaction of PHCl2 with X2C=NNH2 on the activation barriers of these reactions were studied.It was shown that X=F decreases the activation barriers of these reactions more than other substituents (X= Cl or Br).Also, the energy barriers for these reactions are substantially lowered by non-covalent interaction PHCl2 withX2C=NNH2. The PHCl2 retards the formation of the incipient N-C bond from imine to diene while simultaneouslyaccelerating the C-C bond formation.