Nitrogen-doped Carbon Supported Nanocobalt for the Synthesis of Functionalized Triazines via Oxidative Cleavage of Biomass Derived vicinal Diols as Carbon Synthons

Porous Organic Polymer Supported Nano Ruthenium Catalysts for Cascade Aromatization of Quinoxalin-2(1H)-one and C-H Annulation with Alkynes

Selective C-H annulation with alkynes is one of the most useful tools to synthesize heterocycles. Herein, we developed novel porous organic polymers supported ruthenium (POPs-Ru) as highly efficient catalysts for cascade aromatization of quinoxalin-2(1H)-one and C-H annulation with alkynes. Both terminal and internal alkynes were successfully transferred to furo[2,3-b]quinoxaline derivatives with good functional group tolerance and high regioselectivity by using POPs-Ru catalysts. Furthermore, the catalyst exhibited high activity and could be reused at least five times without obvious deactivation of this coupling reaction. This study offers an important platform for the immobilization of molecular metal catalysts for C-H functionalization.

Construction of Spirocyclic Pyrrolo[1,2-a]quinoxalines via Palladium-Catalyzed Hydrogenative Coupling of Phenols and Nitroarenes

The replacement of fossil resources with biomass resources in the construction of N-heterocycles is rapidly attracting research interest. Herein, we report palladium-catalyzed selective hydrogenative coupling of nitroarenes and phenols based on a transfer hydrogenation strategy, allowing straightforward access to spirocyclic pyrrolo- and indolo-fused quinoxalines, a class of compounds found in numerous natural alkaloids. The synthetic protocol is characterized by a broad substrate scope and the utilization of biomass-derived reactants and commercially available catalysts. In such transformations, high-pressure and explosive hydrogen are not required. This report provides a new protocol for converting biomass-derived phenols into value-added nitrogen-containing chemicals.

Nitrogen-Doped Carbon Supported Nanocobalt Catalyst for Hydrogen-Transfer Dearomative Coupling of Quinolinium Salts and Tetrahydroquinolines

A nitrogen-doped carbon supported nanocobalt catalyst was developed and successfully applied for the hydrogen-transfer coupling of quinolinium salts and tetrahydroquinoline compounds. The selective coupling of the C6 sites of tetrahydroquinolines (THQs) with the α sites of quinoline salts generated a series of 2-substituted N-alkyl-tetrahydroquinolines. This catalytic conversion method, which can be employed to synthesize various functionalized tetrahydroquinolines, has several advantages that include excellent hydrogen transfer selectivity, a reusable and inexpensive catalyst, and environmental friendliness.