618-36-0Relevant articles and documents
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Scott,Wrixon
, p. 2339,2366 (1971)
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Key Parameters for the Synthesis of Active and Selective Nanostructured 3d Metal Catalysts Starting from Coordination Compounds – Case Study: Nickel Mediated Reductive Amination
Klarner, Mara,Blach, Patricia,Wittk?mper, Haiko,de Jonge, Niels,Papp, Christian,Kempe, Rhett
, p. 3257 - 3261 (2021)
The design of nanostructured catalysts based on earth-abundant metals that mediate important reactions efficiently, selectively and with a broad scope is highly desirable. Unfortunately, the synthesis of such catalysts is poorly understood. We report here on highly active Ni catalysts for the reductive amination of ketones by ammonia employing hydrogen as a reducing agent. The key functions of the Ni-salen precursor complex during catalyst synthesis have been identified: (1) Ni-salen complexes sublime during catalyst synthesis, which allows molecular dispersion of the metal precursor on the support material. (2) The salen ligand forms a nitrogen-doped carbon shell by decomposition, which embeds and stabilizes the Ni nanoparticles on the γ-Al2O3 support. (3) Parameters, such as flow rate of the pyrolysis gas, determine the carbon supply for the embedding process of Ni nanoparticles.
Indirect reduction of CO2and recycling of polymers by manganese-catalyzed transfer hydrogenation of amides, carbamates, urea derivatives, and polyurethanes
Liu, Xin,Werner, Thomas
, p. 10590 - 10597 (2021/08/20)
The reduction of polar bonds, in particular carbonyl groups, is of fundamental importance in organic chemistry and biology. Herein, we report a manganese pincer complex as a versatile catalyst for the transfer hydrogenation of amides, carbamates, urea derivatives, and even polyurethanes leading to the corresponding alcohols, amines, and methanol as products. Since these compound classes can be prepared using CO2as a C1 building block the reported reaction represents an approach to the indirect reduction of CO2. Notably, these are the first examples on the reduction of carbamates and urea derivatives as well as on the C-N bond cleavage in amides by transfer hydrogenation. The general applicability of this methodology is highlighted by the successful reduction of 12 urea derivatives, 26 carbamates and 11 amides. The corresponding amines, alcohols and methanol were obtained in good to excellent yields up to 97%. Furthermore, polyurethanes were successfully converted which represents a viable strategy towards a circular economy. Based on control experiments and the observed intermediates a feasible mechanism is proposed.
Direct reductive amination of ketones with ammonium salt catalysed by Cp*Ir(iii) complexes bearing an amidato ligand
Dai, Zengjin,Pan, Ying-Min,Wang, Shou-Guo,Yin, Qin,Zhang, Xumu
supporting information, p. 8934 - 8939 (2021/11/04)
A series of half-sandwich Ir(iii) complexes1-6bearing an amidato bidentate ligand were conveniently synthesized and applied to the catalytic Leuckart-Wallach reaction to produce racemic α-chiral primary amines. With 0.1 mol% of complex1, a broad range of ketones, including aryl ketones, dialkyl ketones, cyclic ketones, α-keto acids, α-keto esters and diketones, could be transformed to their corresponding primary amines with moderate to excellent yields (40%-95%). Asymmetric transformation was also attempted with chiral Ir complexes3-6, and 16% ee of the desired primary amine was obtained. Despite the unsatisfactory enantio-control achieved so far, the current exploration might stimulate more efforts towards the discovery of better chiral catalysts for this challenging but important transformation.
