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 meth ods. 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 agre ement with the experimental data. For the reactions with substituted d erivatives of ethylene, the results show that acrylonitrile reacts wit h cyclopentadiene with virtually no stereoselectivity, while for acrol ein, the formation of the endo product is predicted to be the most fav orable from the values of activation Gibbs energies. (C) 1997 John Wil ey & Sons, Inc.