Density functional study of Diels-Alder reactions between cyclopentadiene and substituted derivatives of ethylene

Diels-Alder reactions of cyclopentadiene with ethylene, acrylonitrile, and acrolein were theoretically studied using density functional methods. The results obtained were compared with those corresponding to ab initio methods. Density functional methods, using the B-LYP nonlocal functional, or hybrid methods, yield energy barriers in excellent agreement with the experimental data. For the reactions with substituted derivatives of ethylene, the results show that acrylonitrile reacts with cyclopentadiene with virtually no stereoselectivity, while for acrolein, the formation of the endo product is predicted to be the most favorable from the values of activation Gibbs energies.