Derivatization of azaarenes can create molecules of biological importance, but reductive functionalization of weakly reactive azaarenes remains a challenge. Here the authors show a dearomative, diastereoselective annulation of azaarenes, via ruthenium(II) reductive catalysis, proceeding with excellent selectivity, mild conditions, and broad substrate and functional group compatibility. Mechanistic studies reveal that the products are formed via hydride transfer-initiated β-aminomethylation and α-arylation of the pyridyl core in the azaarenes, and that paraformaldehyde serves as both the C1-building block and reductant precursor, and the use of Mg(OMe)2 base plays a critical role in determining the reaction chemo-selectivity by lowering the hydrogen transfer rate. The present work opens a door to further develop valuable reductive functionalization of unsaturated systems by taking profit of formaldehyde-endowed two functions.

Here, we describe the development of a MOF-derived hierarchically porous ZrO2-supported iridium catalyst (Ir-N@HP-mesoZrO2), featuring sufficient accessible catalytic sites even with ultralow iridium loading. Such a catalyst was successfully applied to selective and direct construction of julolidines via catalytic reductive annulation of readily available quinolines and conjugated enones, proceeding with good substrate and functional group compatibility, reusable catalyst, high step and atom efficiency, and easy applicability for the fabrication of functional molecules. The present work opens a door to further develop useful transformations by merging hydrogen transfer-mediated substrate activation with in situ incorporation of a coupling sequence under heterogeneous reductive catalysis.

Despite the extensive applications, selective and diverse access to N,N′-diarylethane-1,2-diamines remains, to date, a challenge. Here, by developing a bifunctional cobalt single-atom catalyst (CoSA-N/NC), we present a general method for direct synthesis of such compounds via selective reductive coupling of cheap and abundant nitroarenes and formaldehyde, featuring good substrate and functionality compatibility, an easily accessible base metal catalyst with excellent reusability, and high step and atom efficiency. Mechanistic studies reveal that the N-anchored cobalt single atoms (CoN4) serve as the catalytically active sites for the reduction processes, the N-doped carbon support enriches the HCHO to timely trap the in situ formed hydroxyamines and affords the requisite nitrones under weak alkaline conditions, and the subsequent inverse electron demand 1,3-dipolar cycloaddition of the nitrones and imines followed by hydrodeoxygenation of the cycloadducts furnishes the products. In this work, the concept of catalyst-controlled nitroarene reduction to in situ create specific building blocks is anticipated to develop more useful chemical transformations.

Despite the widespread applications of α-hydroxyalkyl cyclic amines, direct and diverse access to such a class of unique vicinal amino alcohols still remains, to date, a challenge. Here, through a strategy of electroreductive α-hydroxyalkylation of inactive N-heteroarenes with ketones or electron-rich arylaldehydes, we describe a room temperature approach for the direct construction of α-hydroxyalkyl cyclic amines, which features a broad substrate scope, operational simplicity, high chemoselectivity, and no need for pressurized H 2 gas and transition metal catalysts. The zinc ion generated from anode oxidation plays a crucial role in the activation of both reactants by decreasing their reduction potentials. The strategy of electroreduction in combination with substrate activation by Lewis acids in this work is anticipated to develop more useful transformations.

Ag eneral catalytic hydrogen transfer-mediated afunctionalization of 1,8-naphthyridines is reported for the first time that benefits from ahydrogen transfer-mediated activation mode for non-activated pyridyl cores.T he pyridyl a-site selectively couples with the C8-site of various tetrahydroquinolines (THQs) to affordn ovel a-functionalized tetrahydro 1,8naphthyridines,aclass of synthetically useful building blocks and potential candidates for the discovery of therapeutic and bio-active products.T he utilization of THQs as inactive hydrogen donors (HDs) appears to be ak ey strategy to overcome the over-hydrogenation barrier and address the chemoselectivity issue.T he developed chemistry features operational simplicity,r eadily available catalyst and good functional group tolerance,a nd offers as ignificant basis for further development of new protocols to directly transform or functionalize inert N-heterocycles.Hydrogen transfer-mediated carbon-carbon and carbonheteroatom bond formations have emerged as powerful tools in synthetic organic chemistry,since they enable key steps in creation of various functionalized products. [1] Forexample,in addition to the hydrogen-borrowing methodologies extensively employed for N-alkylation [2] and C-alkylation, [3] Krische has demonstrated outstanding contributions on the coupling of alcohols with C À Cd ouble/triple bonds. [4] With the use formic acid as the hydrogen donor (HD), the Bruneau group has reported the non-directed C(sp 3 )ÀHb ond alkylation of saturated cyclic amines. [5] In addition, Li and the coworkers have illustrated the conversion of phenol derivatives into amines in the presence of HCO 2 Na. [6] Despite these significant achievements,the strategy of selective trapping of the transient partially hydrogenated N-heteroarenes remains ac hallenge,a lthough it would offer aw ay to access functionalized molecules that are inaccessible or difficult to prepare with existing methods.Thep yridyl ring is ubiquitous in bioactive molecules, functional materials,d yes,a grochemicals,p harmaceuticals, and natural products.H ence,t he direct transformation of pyridyl ring into functionalized frameworks is of significant importance.H owever,s uch ag oal, without the assistance of directing groups [7] or pre-installation of functionalities, [8] remains highly challenging.A sp art of our continuous research interest in construction of N-heterocycles by hydrogen transfer strategies, [9] we have recently demonstrated adirect reductive quinolyl b-C À Halkylation using formic acid as the hydrogen donor (HD). [10] Encouraged by this work, we set out to realize the direct a-functionalization of N-heteroarenes via ahydrogen transfer-mediated activation mode for non-activated pyridyl core.A ss hown in Scheme 1, in the presence of asuitable HD and catalyst (Cat), the first transfer hydrogenation (TH) of pyridyl ring of 2 would afford an allylic amine A and its tautomers (enamine B and imine C). Then, the nucleophile 1 (NuH) would undergo a-addition to imine C,t hereby releasing the...