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

Abstract

This paper is dedicated to the 70th anniversary of Huazhong University of Science and Technology, and to Prof. Matthias Beller on the occasion of his 60th birthday.An easily prepared core-shell heterogeneous nanocobalt catalyst was reported, which could achieve selective reduction of Nheteroarenes 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.

Lanthanide/B(C6F5)3-Promoted Hydroboration Reduction of Indoles and Quinolines with Pinacolborane

“…Catalytic transfer hydrogenation using hydrogen donors other than molecular hydrogen is a promising alternative method because of its versatility, operational simplicity, and safety. A wide variety of hydrogen-atom donors, e.g., alcohols, water, silanes, the HCOOH/Et 3 N azeotrope, Hantzsch esters, ammonia–borane, and diboron reagents, can be used in the catalytic transfer hydrogenation of indoles and quinolines. Pinacolborane (HBpin) is a useful reagent in organic synthesis and has been used in many important transformations such as hydroboration and C–H borylation.…”

Development of a Cobalt Catalyst from ZIF‐67 and Application in the Hydrogenation of N‐Heteroarenes

“…Many methods have been used to prepare these compounds. For example, a variety of hydrogen sources such as hydrogen, [3][4][5] alcohols, [6] formates, [7] silanes, [8] and Hantzsch esters [9] have been used for the chemoselective reduction of quinoline derivatives (Scheme 1a). Among them, direct hydrogenation of nitrogen-containing heteroarenes is an efficient route.…”

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

“…Despite great achievements in employing AB as a hydrogen donor in TH reactions, its application in the reduction of (hetero)­arenes is less developed. So far, electron-deficient Borane–Lewis acids (B­(C 6 F 3 ) 3 ) , including palladium, rhodium, nickel, manganese, copper, , the zirconium–hydride complex, and cobalt-based , catalysts are reported (Figure b). However, most of these systems are mainly limited to quinolines, quinoxalines, indoles, 2,6-disubstituted pyridines, and a few pyridines bearing hydroxyl and amine groups.…”