Copper-Catalyzed Oxidative Multicomponent Annulation Reaction for Direct Synthesis of Quinazolinones via an Imine-Protection Strategy.

Via an imine-protection strategy, we herein present an unprecedented copper-catalyzed oxidative multicomponent annulation reaction for direct synthesis of quinazolinones. The construction of various products is achieved via formation of three C-N and one C-C bonds in conjunction with the benzylic functionalization. The merits of easily available feedstocks, naturally abundant catalyst, good functional group and substrate compatibility, and release of H2O as the byproduct make the developed chemistry a practical way to access quinazolinones.

Site-Specific Oxidative C-H Chalcogenation of (Hetero)Aryl-Fused Cyclic Amines Enabled by Nanocobalt Oxides.

By employing reusable nanocobalt oxides as the catalysts, a site-specific oxidative C-H chalcogenation of (hetero)aryl-fused cyclic amines with various thiols and diselenides is presented for the first time. The reaction proceeds selectively at the sites of the (hetero)aryl rings para to the N atom, and enables access to a wide array of chalcogenyl N-heteroarenes. The merits of the transformation involve high step- and atom-efficiency, excellent substrate and functional compatibility, operational simplicity, and the use of a naturally abundant Co/O2 system. The present work has offered a fundamental basis for the selective synthesis of functional N-heteroarenes from readily available feedstocks.

Direct α-C-H amination using various amino agents by selective oxidative copper catalysis: a divergent access to functional quinolines.

Herein, we present, for the first time, direct dehydrogenative α-C-H amination of tetrahydroquinolines (THQs) using various amino agents by selective aerobic copper catalysis, which enables divergent access to 2-aminoquinolines, the core structures of numerous functional products. In which, the catalyst system preferentially oxidizes the tetrahydroquinolines between two amino reactants, and the presence of TEMPO significantly enhances the capability of the first oxidation of THQs and makes it a kinetically controlled process, thus favoring the C-N bond-forming step. The developed chemistry features broad substrates, excellent functional tolerance, high chemo-selectivity, and no need for pre-preparation of specific aminating agents, which offers a practical way for diverse and atom-economic synthesis of 2-aminoquinolines that are difficult to prepare or inaccessible with the existing C-H amination approaches.