Metal-catalyzed nitrile hydration reactions: The specific contribution of ruthenium (original) (raw)
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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.
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 …, 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.
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.
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.
Ruthenium-Catalyzed Hydration of Nitriles and Transformation of delta-Keto Nitriles to Ene-lactams
Journal of Organic Chemistry, 1992
I Energies in hartrees. Full MP2. CFrozen core MP2. from 1c.l' Moreover, the isotope effects calculated at the MP2/3-21G level (kH/kD = 1.063) and the MP2/6-31G* level (kH/kD = 1.040) are much larger than at the RHF level and in much better agreement with experiment1 The increase in the calculated isotope effect cannot be attributed to an increase in through-space bonding between C1 and C4 at the MP2 level, since, on going from the RHF to the MP2 optimized structure for 1, r14 increases.ls If, as suggested by the results of our calculations on 1, there is some delocalization of the electrons in the C4-H bond in the carbocation, weakening this bond should provide increased stabilization for the cation. This is what was observed experimentally by Adcock et al. on replacing H at C4 by metalloidal substituents.' That the observed rate accelerations are, in fact, a result of enhanced double hyperconjugation can be seen from comparison of the optimized geometries ) and calculated energies for the Csubstituted, bridgehead cations 2 and 3 with those for the corresponding alkanes, 2-H and 3-H.
ACS Catalysis, 2014
Several rhodium(I) complexes, [RhCl(COD)-(PR 3 )], containing potentially cooperative phosphine ligands, have been synthesized and evaluated as catalysts for the selective hydration of organonitriles into amides in water. Among the different phosphines screened, those of general composition P(NR 2 ) 3 led to the best results. In particular, complex [RhCl(COD){P(NMe 2 ) 3 }] was able to promote the selective hydration of a large range of nitriles in water without the assistance of any additive, showing a particularly high activity with heteroaromatic and heteroaliphatic substrates. Employing this catalyst, the antiepileptic drug rufinamide was synthesized in high yield by hydration of 4-cyano-1-(2,6difluorobenzyl)-1H-1,2,3-triazole. For this particular transformation, complex [RhCl(COD){P(NMe 2 ) 3 }] resulted more effective than related ruthenium catalysts. Figure 1. Cooperative effects of functionalized phosphines in Rucatalyzed nitrile hydrations. Research Article pubs.acs.org/acscatalysis