The regioselecti
vity of ring-forming radical reactions is in
vestigated within the framework of the so-called spin-polarized conceptual density functional theory. Two different types of cyclizations were studied.First, a series of model reactions of alkyl- and acyl-substituted radicals were in
vestigated. Next, attentionwas focused on the radical cascade cyclizations of
N-alkenyl-2-aziridinylmethyl radicals (a three-stepmechanism). In both of these reactions, the approaching radical (carbon or nitrogen centered) adds to acarbon-carbon double bond within the same molecule to form a radical ring compound. In this process,the number of electrons is changing from a local point of
view (a charge transfer occurs from one partof the molecule to another one) at constant global spin number
Ns (both the reactant and the product ringcompound are in the doublet state). It is shown that the experimentally obser
ved regioselecti
vitiesfor these ring-closure steps can be predicted using the spin-polarized Fukui functions for radicalattack,
(
r).
