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- ItemAmbient Hydrogenation and Deuteration of Alkenes Using a Nanostructured Ni-Core-Shell Catalyst(Weinheim : Wiley-VCH, 2021) Gao, Jie; Ma, Rui; Feng, Lu; Liu, Yuefeng; Jackstell, Ralf; Jagadeesh, Rajenahally V.; Beller, MatthiasA general protocol for the selective hydrogenation and deuteration of a variety of alkenes is presented. Key to success for these reactions is the use of a specific nickel-graphitic shell-based core–shell-structured catalyst, which is conveniently prepared by impregnation and subsequent calcination of nickel nitrate on carbon at 450 °C under argon. Applying this nanostructured catalyst, both terminal and internal alkenes, which are of industrial and commercial importance, were selectively hydrogenated and deuterated at ambient conditions (room temperature, using 1 bar hydrogen or 1 bar deuterium), giving access to the corresponding alkanes and deuterium-labeled alkanes in good to excellent yields. The synthetic utility and practicability of this Ni-based hydrogenation protocol is demonstrated by gram-scale reactions as well as efficient catalyst recycling experiments. © 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH
- ItemGeneral and selective synthesis of primary amines using Ni-based homogeneous catalysts(Cambridge : RSC, 2020) Murugesan, Kathiravan; Wei, Zhihong; Chandrashekhar, Vishwas G.; Jiao, Haijun; Beller, Matthias; Jagadeesh, Rajenahally V.The development of base metal catalysts for industrially relevant amination and hydrogenation reactions by applying abundant and atom economical reagents continues to be important for the cost-effective and sustainable synthesis of amines which represent highly essential chemicals. In particular, the synthesis of primary amines is of central importance because these compounds serve as key precursors and central intermediates to produce value-added fine and bulk chemicals as well as pharmaceuticals, agrochemicals and materials. Here we report a Ni-triphos complex as the first Ni-based homogeneous catalyst for both reductive amination of carbonyl compounds with ammonia and hydrogenation of nitroarenes to prepare all kinds of primary amines. Remarkably, this Ni-complex enabled the synthesis of functionalized and structurally diverse benzylic, heterocyclic and aliphatic linear and branched primary amines as well as aromatic primary amines starting from inexpensive and easily accessible carbonyl compounds (aldehydes and ketones) and nitroarenes using ammonia and molecular hydrogen. This Ni-catalyzed reductive amination methodology has been applied for the amination of more complex pharmaceuticals and steroid derivatives. Detailed DFT computations have been performed for the Ni-triphos based reductive amination reaction, and they revealed that the overall reaction has an inner-sphere mechanism with H2metathesis as the rate-determining step. © The Royal Society of Chemistry 2020.
- ItemUltra-small cobalt nanoparticles from molecularly-defined Co-salen complexes for catalytic synthesis of amines(Cambridge : RSC, 2020) Senthamarai, Thirusangumurugan; Chandrashekhar, Vishwas G.; Gawande, Manoj B.; Kalevaru, Narayana V.; Zbořil, Radek; Kamer, Paul C.J.; Jagadeesh, Rajenahally V.; Beller, MatthiasWe report the synthesis of in situ generated cobalt nanoparticles from molecularly defined complexes as efficient and selective catalysts for reductive amination reactions. In the presence of ammonia and hydrogen, cobalt-salen complexes such as cobalt(ii)-N,N′-bis(salicylidene)-1,2-phenylenediamine produce ultra-small (2-4 nm) cobalt-nanoparticles embedded in a carbon-nitrogen framework. The resulting materials constitute stable, reusable and magnetically separable catalysts, which enable the synthesis of linear and branched benzylic, heterocyclic and aliphatic primary amines from carbonyl compounds and ammonia. The isolated nanoparticles also represent excellent catalysts for the synthesis of primary, secondary as well as tertiary amines including biologically relevant N-methyl amines. This journal is © The Royal Society of Chemistry.
- ItemA General Catalyst Based on Cobalt Core–Shell Nanoparticles for the Hydrogenation of N-Heteroarenes Including Pyridines(Weinheim : Wiley-VCH, 2020) Murugesan, Kathiravan; Chandrashekhar, Vishwas G.; Kreyenschulte, Carsten; Beller, Matthias; Jagadeesh, Rajenahally V.Herein, we report the synthesis of specific silica-supported Co/Co3O4 core–shell based nanoparticles prepared by template synthesis of cobalt-pyromellitic acid on silica and subsequent pyrolysis. The optimal catalyst material allows for general and selective hydrogenation of pyridines, quinolines, and other heteroarenes including acridine, phenanthroline, naphthyridine, quinoxaline, imidazo[1,2-a]pyridine, and indole under comparably mild reaction conditions. In addition, recycling of these Co nanoparticles and their ability for dehydrogenation catalysis are showcased. © 2020 The Authors. Published by Wiley-VCH GmbH