C-hydroxyalkylation ofN-arylanilines with polyfluorocarbonyl compounds. Theoretical study

Abstract

Quantum chemical AM1 calculations with full geometry optimization are carried out forN-methylaniline (2), tetrahydroquinoline (3), indoline (4) molecules, as well as for the products and reaction intermediates of their C-hydroxyalkylation with hexafluoroacetone (1). Enthalpies of formation, frontier orbital energies, and atomic charge distributions are determined for all systems examined. These values are used to estimate the relative stabilities of adducts formed by donor-acceptor interaction between amino- and carbonyl groups using the Klopman perturbation theory. The complexes of1 with2 and1 with4 are concluded to have the longest and shortest lifetimes, respectively. The results of the theoretical study allow one to explain the experimentally observed increase in the propensity forortho-C-hydroxyalkylation in the series2<3<4. The reduction of the ability of methyl trifluoropyruvate to undergoortho-C-hydroxyalkylation is shown to be a consequence of the greater stabilities of its arylamine complexes.