Spin-Polarized Conceptual Density Functional Theory Study of the Regioselectivity in Ring Closures of Radicals

• Published in: Journal of organic chemistry 2007-01, Vol.72 (2), p.348-356
• Main Authors: Pintér, B, De Proft, F, Van Speybroeck, V, Hemelsoet, K, Waroquier, M, Chamorro, E, Veszprémi, T, Geerlings, P
• Format: Article
• Language: English
• Subjects: Chemistry; Cyclization; Exact sciences and technology; Free Radicals - chemical synthesis; Free Radicals - chemistry; Kinetics and mechanisms; Models, Chemical; Organic chemistry; Quantum Theory; Reactivity and mechanisms; Stereoisomerism
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo0613885

The regioselectivity of ring-forming radical reactions is investigated 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 investigated. Next, attention was focused on the radical cascade cyclizations of N-alkenyl-2-aziridinylmethyl radicals (a three-step mechanism). In both of these reactions, the approaching radical (carbon or nitrogen centered) adds to a carbon−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 part of the molecule to another one) at constant global spin number N s (both the reactant and the product ring compound are in the doublet state). It is shown that the experimentally observed regioselectivities for these ring-closure steps can be predicted using the spin-polarized Fukui functions for radical attack, ( r ).