CYCLOADDITION OF ACRYLONITRILE TO ALLENE - COMPUTED REACTION-PATH (AM1) AND INTRAMOLECULAR SECONDARY ISOTOPE EFFECT

The reaction path for cycloaddition of acrylonitrile to allene was com puted using the AM1 Hamiltonian with limited configuration interaction (C.I. = 4). Cycloaddition is found to proceed stepwise via a biradica l intermediate, in confirmation of the conclusion reached by Dolbier a nd Dai on the basis of the intramolecular and intermolecular H/D kinet ic isotope effects on the reaction. A transition state theory calculat ion of the ratio of the two isotopomeric products obtained from cycloa ddition of acrylonitrile with gem-dideuteroallene is in good agreement with the experimental observations. A parallel set of computations on the cycloaddition of fluoroethylene to allene yielded similar results .