title: Heterolytic (2 e) vs Homolytic (1 e) Oxidation Reactivity: N-H versus C-H Switch in the Oxidation of Lactams by Dioxirans.
abstract: Dioxiranes are powerful oxidants that can act via two different mechanisms: 1) homolytic (H abstraction and oxygen rebound) and 2) heterolytic (electrophilic oxidation). So far, it has been reported that the nature of the substrate dictates the reaction mode independently from the dioxirane employed. Herein, we report an unprecedented case in which the nature of the dioxirane rules the oxidation chemoselectivity. In particular, a switch from C-H to N-H oxidation is observed in the oxidation of lactams moving from dimethyl dioxirane (DDO) to methyl(trifluoromethyl)dioxirane (TFDO). A physical organic chemistry study, which combines the oxidation with two other dioxiranes methyl(fluoromethyl)dioxirane, MFDO, and methyl(difluoromethyl)dioxirane, DFDO, with computational studies, points to a diverse ability of the dioxiranes to either stabilize the homo or the heterolytic pathway.
authors: CNR-ICCOM, UOS Bari, Via Orabona 4, 70126, Bari, Italy.
authors: Cosimo
authors: C
authors: Annese
authors: CNR-ICCOM, UOS Bari, Via Orabona 4, 70126, Bari, Italy.|Dipartimento di Chimica, Università di Bari "A. Moro", Via Orabona 4, 70126, Bari, Italy.
authors: Lucia
authors: 0000-0002-4960-728X
authors: L
authors: D'Accolti
authors: CNR-ICCOM, UOS Bari, Via Orabona 4, 70126, Bari, Italy.
authors: Caterina
authors: C
authors: Fusco
authors: Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy.
authors: Giulia
authors: 0000-0001-8304-0443
authors: G
authors: Licini
authors: Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy.
authors: Cristiano
authors: 0000-0003-1749-7482
authors: C
authors: Zonta
mesh_terms: D004852:Epoxy Compounds / Q000737:chemistry*; D054879:Halogenation; D007769:Lactams / Q000737:chemistry*; D008745:Methylation; D016877:Oxidants / Q000737:chemistry*; D010084:Oxidation-Reduction; D013816:Thermodynamics
chemical_list: D004852:Epoxy Compounds; D007769:Lactams; D016877:Oxidants; C061799:dioxirane
keywords: MP2 calculations; chemoselectivity; dioxiranes; lactams; oxidation