The oxidation of phenols is the subject of extensive investigation, but there are few catalytic aerobic examples that are chemo- and regioselective. Here we describe conditions for the ortho-oxygenation or oxidative coupling of phenols under copper (Cu)-catalyzed aerobic conditions that give rise to ortho-quinones, biphenols or benzoxepines. We demonstrate that each product class can be accessed selectively by the appropriate choice of Cu(I) salt, amine ligand, desiccant and reaction temperature. In addition, we evaluate the effects of substituents on the phenol and demonstrate their influence on selectivity between ortho-oxygenation and oxidative coupling pathways. These results create an important precedent of catalyst control in the catalytic aerobic oxidation of phenols and set the stage for future development of catalytic systems and mechanistic investigations.

The importance of aromatic C-O, C-N, and C-S bonds necessitates increasingly efficient strategies for their formation. Herein, we report a biomimetic approach that converts phenolic C-H bonds into C-O, C-N, and C-S bonds at the sole expense of reducing dioxygen (O2) to water (H2O). Our method hinges on a regio- and chemoselective copper-catalyzed aerobic oxygenation to provide ortho-quinones. ortho-Quinones are versatile intermediates, whose direct catalytic aerobic synthesis from phenols enables a mild and efficient means of synthesizing polyfunctional aromatic rings.

Keywords: Atom-economy / Homogeneous catalysis / C-H activation / Heteroaryl halides / Isoxazole / Palladium 4-Arylisoxazoles can be easily prepared by a palladium-catalysed C-H bond activation/arylation of 3,5-disubstituted isoxazoles using aryl or heteroaryl bromides. Good yields were generally obtained by using 0.1-0.5 mol-% of the airstable PdCl 2 complex as the catalyst. A range of functional groups such as acetyl, formyl, ester, fluoro, nitro, trifluoro-

PEG400 is described herein as a suitable medium for the condensation of various 2‐amino pyridines with α‐bromo ketones. 2‐Arylimidazo[1,2‐a]pyridines were synthetized in a short time through microwave irradiation in moderate to excellent yields. After optimization, a convenient one‐pot process enabled access to 2,3‐diarylimidazo[1,2‐a]pyridines by using a reduced amount of palladium catalyst without ligand for the C–H arylation step in the same environmentally‐sound medium.