Room-Temperature Electroreductiveα-Alkylation of N-Heteroarenes with Styrenes

Despite their interesting applications,direct and diverse syntheses of aryl-fused 2-alkyl cyclic amines still remain challenging.Here,the concept of incorporating a C–C coupling process into the N-heteroaryl reduction was successfully applied to fulfill such a synthetic purpose.Due to our use of controllable electroreduction coupled with proton abstraction,we can report a room-temperature reductiveα-alkylation of the inert N-heteroarenes with abundantly available styrenes in an undivided Zn(+)/C(−)cell.This proceeds with good substrate compatibility and operational simplicity,utilizes cost-effective sacrificial Zn-anode,exhibits high selectivity,and does not need pressurized H2 gas and transition-metal catalysts.This current work offers a useful platform for direct construction of valuable aryl-fused 2-alkyl cyclic amines that are difficult to access with conventional methods.

Asymmetric Hydrogenation of Tetrapyridine-Type N-Heteroarenes Using Phosphine-Free Ruthenium Diamine Catalysts

Chiral ruthenium-catalyzed enantioselective hydrogenation of tetrapyridine-type N-heteroarenes was firstly developed.The partial reduction of adjacent tetraheteroaromatic substrates proceeded smoothly in the presence of phosphine-free chiral cationic ruthenium diamine complexes,affording unprecedented high reactivity,enantioselecitivity and diastereoselectivity(up to 93%yield,>99%ee and 92:8 dr).The potential application of chiral tetradentate pyridine-amine products as chiral ligands has been demonstrated in the Cu-catalyzed asymmetric Friedel–Crafts alkylation reaction between indoles and nitroalkenes.

Manganese-Catalyzed Regioselective Hydroboration of Quinolines via Metal-Ligand Cooperation

Selective reduction of readily available N-heteroarenes is important in both organic synthesis and chemical biology.Herein,we describe ligand-controlled regiodivergent hydroboration of quinolines using well-defined amido-manganese catalysts,with an emphasis on the rarely reported 1,4-regioselectivity.Mechanistic studies showed that 1,2-hydroboration of quinoline was kinetically favorable and reversible,whereas 1,4-hydroboration was under thermodynamic control.Using a 1-methyimidazolebased pincer amido-manganese complex as the catalyst,cooperative C-H…N andπ…πnoncovalent interactions between the 1-methyimidazole moiety and quinoline substrates enabled kinetic accessibility of 1,4-hydroboration,giving thermodynamically favored 1,4-hydroborated quinolines as the major products.On this basis,Mn-catalyzed 1,4-hydroboration of a series of substituted quinolines proceeded smoothly in high yields.A high turnover number of 2500 was achieved in this reaction with satisfying regioselectivity.This transformation could be further applied to the C3-selective functionalization of quinolines,highlighting the synthetic utility of this methodology.In contrast,using a pyridine-based pincer amido-manganese complex as the catalyst,which lacked the C-H…N interaction,the free-energy barrier for 1,4-hydroboration significantly increased through a N-B…N interaction between the“HMn-NB”species and quinoline,resulting in the kinetically favored 1,2-hydroboration product with excellent regioselectivity.

Seeing Is Believing:A Wavy N-Heteroarene with 20 Six-Membered Rings Linearly Annulated in a Row

Structurally well-defined arenes with higher numbers of linearly-fused six-member rings(n≥10)are important and highly desirable not only because of their experimental challenges but also due to their fundamental interests and the curiosity of their structure-property relationships.In this research,we successfully synthesized a novel large N-heteroarene(N20)with 20 linearly-fused six-membered rings,which is the longest N-heteroarene(4.7 nm)confirmed by single-crystal X-ray diffraction(SCXRD)analysis so far.The as-prepared arene displays a wave-like framework rather than a rigid plane.Moreover,N20 shows high molar absorptivity of 364,000 M^(−1) cm^(−1) with its fluorescence extended to the near-infrared region.

Photocatalytic Decarboxylative Minisci Reaction Catalyzed by Palladium-Loaded Gallium Nitride

The decarboxylative Minisci reaction is a versatile tool for the direct C-H alkylation of heteroarenes,where stoichiometric amounts of oxidants or expensive,precious metal reagents are commonly used.Herein,we reported a photodriven decarboxylative Minisci reaction enabled by a gallium nitride-based heterogeneous photocatalyst under mild conditions.This method can be effectively applied to a broad substrate scope of acids,including primary,secondary,and tertiary carboxylic acids and N-heteroarenes effectively.The practicability and robustness of the approach are demonstrated for the functionalization of biologically active compounds.