Cu‐Catalyzed Chemoselective Reduction of N ‐Heteroaromatics with NH 3 · BH 3 in Aqueous Solution

Transfer Hydrogenation of N- and O-Containing Heterocycles Including Pyridines with H3N-BH3 Under the Catalysis of the Homogeneous Ruthenium Precatalyst

In this study, we report a transfer hydrogenation protocol that utilizes borane-ammonia (H3N-BH3) as the hydrogen source and a commercially available RuCl3·xH2O precatalyst for the selective aromatic reduction of quinolines, quinoxalines, pyridines, pyrazines, indoles, benzofurans, and furan derivatives to form the corresponding alicyclic heterocycles in good to excellent isolated yields. Applications of this straightforward protocol include the efficient preparation of useful key pharmaceutical intermediates, such as donepezil and flumequine, including a biologically active compound.

Core-Shell Nano-Cobalt Catalyzed Chemoselective Reduction of N-Heteroarenes with Ammonia Borane

An easily prepared core-shell heterogeneous nanocobalt catalyst was reported, which could achieve selective reduction of N-heteroarenes with ammonia borane under mild conditions and ambient atmosphere. Various quinoline, quinoxaline, naphthyridine, isoquinoline, acridine, and phenanthroline derivatives were hydrogenated with high selectivity and efficiency. Notably, substrates bearing sensitive functional groups under molecular hydrogen reduction conditions, such as cyano, ester, and halogens were well tolerated by the catalytic system. Moreover, with our novel method several bioactive molecules were prepared. Also, this catalyst could be applied in the liquid organic hydrogen storage system by reversible hydrogenation and dehydrogenation of heteroarene in high efficiencies.

Rh-Catalyzed diastereoselective addition of arylboronic acids to α-keto N-tert-butanesulfinyl aldimines: synthesis of α-amino ketones

Herein we present a diastereoselective addition of arylboronic acids to α-keto N-tert-butanesulfinyl aldimines catalyzed by a Rh(i) catalyst.

Chemoselective reduction of α,β-unsaturated ketones to allylic alcohols under catalyst-free conditions

A strategy of chemoselective reduction of α, β-unsaturated ketones was developed in our group. H3N·BH3 would prefer to coordinate with CO bond, forming six-membered ring, and ketones were hydrogenated via concerted double-hydrogen-transfer process.

Switching Selectivity in Copper-Catalyzed Transfer Hydrogenation of Nitriles to Primary Amine-Boranes and Secondary Amines under Mild Conditions

A simple and efficient copper-catalyzed selective transfer hydrogenation of nitriles to primary amine-boranes and secondary amines with an oxazaborolidine-BH₃ complex is reported. The selectivity control was achieved under mild conditions by switching the solvent and the copper catalysts. More than 30 primary amine-boranes and 40 secondary amines were synthesized via this strategy in high selectivity and yields of up to 95%. The strategy was applied to the synthesis of ¹⁵N labeled in 89% yield.

Regioselective Cross-Coupling of Isatogens with Boronic Acids to Construct 2,2-Disubstituted Indolin-3-one Derivatives

Herein we present a transition-metal-free cross-coupling reaction of isatogens with boronic acids through a 1,4-metalate shift of a boron "ate" complex. This coupling reaction provides a feasible method to deliver valuable 2,2-disubstituted indolin-3-one derivatives with excellent regioselectivity, which exhibit operational simplicity, good functional group tolerance, and a broad substrate scope.

Modular Synthesis of Polysubstituted Quinolin-3-amines by Oxidative Cyclization of 2-(2-Isocyanophenyl)acetonitriles with Organoboron Reagents

Polysubstituted quinolin-3-amines are vital structural motifs because of their broad biological activities as well as versatile transformational abilities. However, they are not easily accessible. We disclose a protocol with Mn(III) acetate as a mild one-electron oxidant promoting a radical process to construct polysubstituted quinolin-3-amines. 2-(2-Isocyanophenyl)acetonitriles and organoboron reagents are suitable substrates for this reaction. The remarkable advantages of this protocol are the practical method, mild approach, high reaction efficiency, and good compatibility of functional groups, providing straightforward access to functional quinoline derivatives.