Theoretical study of 1,3-dipolar cycloaddition reactions of diphenylnitrilimine with highly fluorinated dipolarophiles

The 1,3-dipolar cycloaddition reactions of diphenylnitrilimine with various fluorinated dipolarophiles have been investigated with the use of ab initio molecular orbital calculations to elucidate the mechanistic aspects of the reaction based on the kinetic and frontier molecular orbital (FMO) theoretical points of views. Structure optimizations were performed with the RHF/3-21G, RHF/6-31G* and density functional B3LYP/6-31G* methods. The transition state geometries and energy barriers depend on the level of calculations. The results provide a good prediction of the relative rates observed experimentally. Regioselectivity of the products of the reaction is also predicted reliably by the calculations. The perturbative analysis shows a strong HOMO (dipole)-LUMO (dipolarophile) interaction as the principal reason for the reactivity in these 1,3-dipolar cycloaddition reactions. (C) 2001 Elsevier Science B.V. All rights reserved.