ChemInform Abstract: Aqueous and Biphasic Nitrile Hydration Catalyzed by a Recyclable Ru(II) Complex under Atmospheric Conditions (original) (raw)
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Metal-catalyzed nitrile hydration reactions: The specific contribution of ruthenium
Journal of Organometallic Chemistry, 2014
The hydration of nitriles is an atom economical route to generate primary amides of great academic and industrial significance. From an academic perspective, considerable progress has been made toward the development of transition metal catalysts able to promote this hydration process under mild conditions. In this context, with regard to activity, selectivity, functional group compatibility and modes of reactivity, the most versatile nitrile hydration catalysts discovered to date are based on ruthenium complexes. Herein, a comprehensive account of the different homogeneous ruthenium catalysts described in the literature is presented. Heterogeneous ruthenium-based systems are also discussed.
Self-Assembled Bidentate Ligands for Ruthenium-Catalyzed Hydration of Nitriles
Organometallics, 2007
NoVel bis(acetylacetonato)ruthenium(II) complexes bearing the 6-diphenylphosphino-N-piValoyl-2-aminopyridine and 3-diphenylphosphinoisoquinolone ligands were synthesized. Molecular structures of these complexes were studied in solution and also in the solid state, and unusual hydrogen-bonding patterns were identified. The prepared compounds constitute actiVe catalysts for the hydration of nitriles to amides under neutral conditions.
ChemistrySelect, 2018
An efficient protocol for direct transformation of aldehydes into of nitrile and amide derivatives using Ru(Cl)‐salen complex as a solvent selective homogeneous catalyst is developed. The catalyst has also been explored for hydration of nitrile to synthesize the primary amides in an aqueous medium. Additionally, a mechanistic pathway for the dehydration of aldoxime to nitrile and hydration of nitrile to amide was studied using gas chromatography. The catalyst has been fully characterized by using spectroscopic techniques such as IR spectroscopy, MALDI‐TOF mass analysis and 1H NMR technique. A simple work up procedure, lower catalyst to substrate ratio, and good to excellent yields of the products, higher turnover number and turnover frequency makes the protocol more advantageous and feasible.
Journal of the …, 2003
The indenylruthenium hydride complex (η 5 -C9H7)Ru(dppm)H was found to be active in catalyzing the hydration of nitriles to amides. The chloro analogue (η 5 -C9H7)Ru(dppm)Cl was, however, found to be inactive. Density functional theory calculations at the B3LYP level provide explanations for the effectiveness of the hydride complex and the ineffectiveness of the chloro complex in the catalysis. It is learned that the presence of a Ru-H‚‚‚H-OH dihydrogen-bonding interaction in the transition state lowers the reaction barrier in the case of (η 5 -C9H7)Ru(dppm)H, but in the chloro system, the corresponding transition state does not contain this type of interaction and the reaction barrier is much higher. A similar dihydrogenbond-promoting effect is believed to be responsible for the catalytic activity of the hydrotris(pyrazolyl)borato (Tp) ruthenium complex TpRu(PPh 3)(CH3CN)H in CH3CN hydration. The chloro analogue TpRu(PPh3)(CH3CN)Cl shows no catalytic activity.
Catalysts
A new synthetic method for obtaining [RhCl(cod)(NHC)] complexes (1–4) (cod = η4-1,5-cyclooctadiene, NHC = N-heterocyclic carbene: IMes, SIMes, IPr, and SIPr, respectively) is reported together with the catalytic properties of 1–4 in nitrile hydration. In addition to the characterization of 1–4 in solution by 13C NMR spectroscopy, the structures of complexes 3, and 4 have been established also in the solid state with single-crystal X-ray diffraction analysis. The Rh(I)-NHC complexes displayed excellent catalytic activity in hydration of aromatic nitriles (up to TOF = 276 h−1) in water/2-propanol (1/1 v/v) mixtures in air.
Journal of the American Chemical Society, 2003
The indenylruthenium hydride complex (η 5-C9H7)Ru(dppm)H was found to be active in catalyzing the hydration of nitriles to amides. The chloro analogue (η 5-C9H7)Ru(dppm)Cl was, however, found to be inactive. Density functional theory calculations at the B3LYP level provide explanations for the effectiveness of the hydride complex and the ineffectiveness of the chloro complex in the catalysis. It is learned that the presence of a Ru-H‚‚‚H-OH dihydrogen-bonding interaction in the transition state lowers the reaction barrier in the case of (η 5-C9H7)Ru(dppm)H, but in the chloro system, the corresponding transition state does not contain this type of interaction and the reaction barrier is much higher. A similar dihydrogenbond-promoting effect is believed to be responsible for the catalytic activity of the hydrotris(pyrazolyl)borato (Tp) ruthenium complex TpRu(PPh 3)(CH3CN)H in CH3CN hydration. The chloro analogue TpRu(PPh3)(CH3CN)Cl shows no catalytic activity.
Chemistry (Weinheim an der Bergstrasse, Germany), 2017
A Ni(II) complex 1 containing pyridyl- and hydroxy-functionalized N-heterocyclic carbenes (NHC) is synthesized and its catalytic utility for selective nitrile hydration to amide under base-free condition is evaluated. The title compound exploits hemilabile pyridyl unit to interact with a catalytically relevant water molecule via hydrogen-bonding and promote nucleophilic water attack to the nitrile. A wide variety of nitriles are hydrated to the corresponding amides including pharmaceutical drugs Rufinamide, Rifater and Piracetam. Synthetically challenging α-hydroxyamides are accessed from cyanohydrins under neutral conditions. Related catalysts that lack the pyridyl unit (2 and 4) are not active whereas those containing both the pyridyl and the hydroxy or only the pyridyl pendant (1 and 3) show substantial activity. A linkage isomer 1' where hydroxy group is bound to the metal instead of the pyridyl was isolated under different crystallization conditions insinuating ligand hemil...