title: Kinetic and theoretical study of 4-exo ring closures of carbamoyl radicals onto C=C and C=N bonds.
abstract: Carbamoyl radicals were generated from oxime oxalate amides, and the kinetics of their 4-exo cyclizations onto C=C and C=NO bonds, leading to beta-lactam-containing species, were studied by EPR spectroscopy. DFT computations with model carbamoyl radicals predicted 4-exo ring closures onto C=NO bonds to be facile, especially when tert-butyl substituents were present. The reverse ring-opening reactions were predicted to have much higher activation energies. Experimental evidence also favored slow reverse ring opening.
authors.affiliation: School of Chemistry, University of St. Andrews, St. Andrews, Fife, UK KY16 9ST.
authors.forename: Gino A
authors.initials: GA
authors.lastname: Dilabio
authors.forename: Eoin M
authors.initials: EM
authors.lastname: Scanlan
authors.forename: John C
authors.initials: JC
authors.lastname: Walton