Non-symmetrically substituted phenoxazinones from laccase-mediated oxidative cross-coupling of aminophenols: an experimental and theoretical insight
作者:Frédéric Bruyneel、Georges Dive、Jacqueline Marchand-Brynaert
DOI:10.1039/c1ob05795b
日期:——
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 1H-, 13C- and 31P-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.
在一种商用漆酶的催化下,取代的邻氨基苯酚发生氧化交叉偶联反应,首次生成了非对称取代的苯并噁嗪酮。通过 1H-、13C- 和 31P-NMR 以及 HPLC-PDA 和 HPLC-MS/MS,在四种潜在杂环框架中只鉴定出两种取代的苯并噁嗪酮,并通过 DFT 研究予以确认。底物的氧化还原特性、其相对转化率以及选定底物的刚性对接导致重新审视了苯并噁嗪酮生物合成的机理途径。我们的建议涉及漆酶的第一次正式双电子氧化和第一次分子间 1,4- 共轭加成,这确保了观察到的区域选择性。