Search Results
Towards a general ruthenium-catalyzed hydrogenation of secondary and tertiary amides to amines
2016, Cabrero-Antonino, Jose R., Alberico, Elisabetta, Junge, Kathrin, Junge, Henrik, Beller, Matthias
A broad range of secondary and tertiary amides has been hydrogenated to the corresponding amines under mild conditions using an in situ catalyst generated by combining [Ru(acac)3], 1,1,1-tris(diphenylphosphinomethyl)ethane (Triphos) and Yb(OTf)3. The presence of the metal triflate allows to mitigate reaction conditions compared to previous reports thus improving yields and selectivities in the desired amines. The excellent isolated yields of two scale-up experiments corroborate the feasibility of the reaction protocol. Control experiments indicate that, after the initial reduction of the amide carbonyl group, the reaction proceeds through the reductive amination of the alcohol with the amine arising from collapse of the intermediate hemiaminal.
General and selective synthesis of primary amines using Ni-based homogeneous catalysts
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.
Ultra-small cobalt nanoparticles from molecularly-defined Co-salen complexes for catalytic synthesis of amines
2020, Senthamarai, Thirusangumurugan, Chandrashekhar, Vishwas G., Gawande, Manoj B., Kalevaru, Narayana V., Zbořil, Radek, Kamer, Paul C.J., Jagadeesh, Rajenahally V., Beller, Matthias
We 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.