title: Non-symmetrically substituted phenoxazinones from laccase-mediated oxidative cross-coupling of aminophenols: an experimental and theoretical insight.
abstract: Oxidative cross-coupling reactions of substituted o-aminophenols were catalyzed by a commercial laccase to produce non-symmetrically substituted phenoxazinones for the first time. Identification by (1)H-, (13)C- and (31)P-NMR, and by HPLC-PDA and HPLC-MS/MS of exclusively two kinds of substituted phenoxazinones out of four potential heterocyclic frameworks was confirmed by a DFT study. The redox-properties of the substrates, their relative rates of conversion and the rigid docking of selected substrates led to a revisited mechanistic pathway for phenoxazinones biosynthesis. Our suggestions concern both the first formal two-electron oxidation by laccase and the first intermolecular 1,4-conjugated addition which secures the observed regioselectivity.
authors.affiliation: Institute of Condensed Matter and Nanosciences, Organic and Medicinal Chemistry, Université catholique de Louvain, Louvain-la-Neuve, Belgium.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Bruyneel
authors.forename: Georges
authors.initials: G
authors.lastname: Dive
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Marchand-Brynaert
mesh_terms: D000627:Aminophenols / Q000737:chemistry* / Q000378:metabolism; D001688:Biological Products / Q000737:chemistry; D042845:Laccase / Q000378:metabolism*; D008958:Models, Molecular; D015394:Molecular Structure; D010078:Oxazines / Q000138:chemical synthesis*; D010084:Oxidation-Reduction; D013237:Stereoisomerism; D013379:Substrate Specificity; D055454:Trametes / Q000201:enzymology*
chemical_list: D000627:Aminophenols; D001688:Biological Products; D010078:Oxazines; C020456:phenoxazinone; D042845:Laccase