Calculations concerning the reactivity of enolate ions of ketones towards radicals.

PIERINI, ADRIANA B.; BOROSKY, GABRIELA L.; BAUMGARTNER, MARÍA T.

Londres

Congreso; 5th World Congress of Theoretically Oriented Chemists, WATOC?99; 1999

WATOC

The coupling reaction of a carbon centred radical with a carbanionic nucleophile is a crucial step for the formation of a C-C bond in nucleophilic substitution mechanisms that take place through electron transfer steps. In studies of the reactions of aromatic and aliphatic radicals with carbanions derived from ketones, this step had been found to be determined by the HOMO energy of the carbanion and the DEp of the system (SOMO of the formed radical anion ? HOMO of the nucleophile).1 This DEp has been related to the lost in resonance energy of the p system.             Ab initio, semiempirical and density functional studies has been performed for the calculation of the potential energy surface of the reaction of enolate ions of ketones with a carbon radical. Relative reactivities have been analysed according to the calculated energies of the system. Known experimental results have been considered for the validation of the theoretical calculations. 1 G. L. Borosky, A. B. Pierini and R. A. Rossi, J. Org. Chem., 1992, 57, 247; R. A. Rossi, A. B. Pierini and G. L. Borosky, J. Chem. Soc., Perkin Trans. II, 1994, 2577.