Ruthenium-Catalyzed Dehydrogenative β‑Benzylation of 1,2,3,4-Tetrahydroquinolines with Aryl Aldehydes: Access to Functionalized Quinolines

A new benzylation protocol, enabling straightforward access to β-benzylated quinolines, has been demonstrated. By employing readily available [RuCl₂(<i>p</i>-cymene)]₂ as a catalyst and O₂ as a sole green oxidant, various 1,2,3,4-tetrahydro­quinolines were efficiently converted in combination with aryl aldehydes into desired products in a step- and atom-economic fashion together with the advantages of excellent functional group tolerance and chemoselectivity, offering an important basis for the transformation of saturated <i>N</i>-heterocycles into functionalized <i>N</i>-heteroaromatics via a dehydrogenative cross-coupling strategy. Mechanistic investigations support that the reaction undergoes a monodehydrogenation-triggered β-benzylation mode

Aerobic Copper-Catalyzed Halocyclization of Methyl <i>N</i>‑Heteroaromatics with Aliphatic Amines: Access to Functionalized Imidazo-Fused <i>N</i>‑Heterocycles

A new aerobic copper-catalyzed halocyclization reaction of methyl <i>N</i>-heteroaromatics and aliphatic amines has been developed, which enables straightforward access to functionalized imidazo-fused <i>N</i>-heterocycles with the merits of good functional tolerance, use of easily available copper salts as the catalysts, lithium halides as the halogen sources, and O₂ as a sole oxidant. Due to the reaction features’ selective introduction of halogen functionalities to the newly formed imidazo ring, further extensions of the developed chemistry toward synthetic diversity, including effective access to functional materials, are easily envisioned

Ruthenium-Catalyzed Straightforward Synthesis of 1,2,3,4-Tetrahydronaphthyridines via Selective Transfer Hydrogenation of Pyridyl Ring with Alcohols

Through a ruthenium-catalyzed selective hydrogen transfer coupling reaction, a novel straightforward synthesis of 1,2,3,4-tetrahydronaphthyridines from <i>o</i>-aminopyridyl methanols and alcohols has been developed. The synthetic protocol proceeds in an atom- and step-economic fashion together with the advantages of operational simplicity, broad substrate scope, production of water as the only byproduct, and no need for external reducing reagents such as high pressure H₂ gas, offering a highly practical approach for accessing this type of structurally unique products

Aerobic Copper-Catalyzed Synthesis of Benzimidazoles from Diaryl- and Alkylamines via Tandem Triple C–H Aminations

Through radical-induced tandem triple C–H aminations with free amines as the aminating agents, we herein present a precedent on aerobic copper-catalyzed synthesis of 5-diarylamino benzimidazoles, a class of optoelectronic device analogues by combining two molecules of diarylamines and one molecule of alkylamine in one single operation. The developed chemistry proceeds with the merits of a natural abundant copper/O₂ catalyst system, readily available feedstocks, broad substrate scope, good functional group tolerance, exclusive regio- and chemoselectivity, high step and atom efficiency, which offers an important basis for further construction of functional products that are inaccessible or difficult to prepare with the existing methods by employing catalytic tandem C–H amination strategy