Arene–Ruthenium(II) Complexes Containing Inexpensive Tris(dimethylamino)phosphine: Highly Efficient Catalysts for the Selective Hydration of Nitriles into Amides
摘要:
The catalytic hydration of nitriles into amides, in water under neutral conditions, has been studied using a series of arene-ruthenium(II) derivatives containing the commercially available and inexpensive ligand tris(dimethylamino)phosphine. Among them, best results were obtained with the complex [RuCl2(eta(6)-C6Me6){P(NMe2)(3)}], which selectively provided the desired amides in excellent yields and short times (TOF values up to 11 400 h(-1)). The process was operative with both aromatic, heteroaromatic, aliphatic, and alpha,beta-unsaturated organonitriles and showed a high functional group tolerance. The stability of [RuCl2(eta(6)-C6Me6){P(NMe2)(3)}] in water was evaluated, observing its progressive decomposition into the less-active dimethylamine nithenium(II) complex [RuCl2(eta(6)-C6Me6)(NHMe2)] by hydrolysis of the coordinated P(NMe2)(3) ligand. The X-ray crystal structure determination of the toluene complex [RuCl2(eta(6)-C6H5Me){P(NMe2)(3)}] is also included.
Cyanohydrin Hydration with [Ru(η6-p-cymene)Cl2PR3] Complexes
摘要:
The catalytic hydration of cyanohydrins to their corresponding alpha-hydroxyamides provides a route to industrially useful alpha-hydroxy amides, alpha-hydroxy esters, alpha-hydroxy carboxylic acids, and their acrylic derivatives. However, until now, no homogeneous nitrile hydration catalyst has been capable of complete conversion of cyanohydrins to their corresponding amides because cyanohydrins degrade to produce cyanide, which poisons the catalyst. Because the cyanohydrin degradation is an equilibrium process, it was hypothesized that a faster nitrile hydration catalyst would be capable of hydrating the cyanohydrin before degradation occurs. Secondary coordination sphere effects were used to develop a faster catalyst based on the [Ru(eta(6)-arene)Cl-2(PR3)] scaffold. A series of [Ru(eta(6)-p-cymene)Cl-2(PR3)] complexes, where R = NMe2, OMe, Et, was synthesized, and their activity toward cyanohydrin hydration was determined. The complex [Ru(eta(6)-p-cymene)Cl-2(P(NMe2)(3))] is an excellent catalyst, and the unprecedented complete conversion of a cyanohydrin to its corresponding amide using a homogeneous catalyst was achieved with glycolonitrile and lactonitrile.
Mechanistic Investigations and Secondary Coordination Sphere Effects in the Hydration of Nitriles with [Ru(η<sup>6</sup>-arene)Cl<sub>2</sub>PR<sub>3</sub>] Complexes
作者:Spring Melody M. Knapp、Tobias J. Sherbow、Robert B. Yelle、Lev N. Zakharov、J. Jerrick Juliette、David R. Tyler
DOI:10.1021/om301079u
日期:2013.2.11
investigated. Ligands that are capable of acting as hydrogenbondacceptors with the entering water molecule result in faster rates and higher yields than non-hydrogen-bonding ligands. The faster rates are attributable to the H-bonding-facilitated deprotonation of the water as the oxygen of the water bonds to the coordinated nitrile. DFT calculations on the proposed H-bonding intermediates support this interpretation
使用的[Ru(η腈至酰胺水合反应的机理6 -arene)氯2(PR 3)]配合物作为催化剂进行了研究(η 6 -arene = C 6 H ^ 6,p -cymene,C 6我6 ; R = NMe 2,OMe,OEt,Et,iPr)。实验表明,该机理涉及以下一般反应顺序:腈配体取代氯化物配体;水对分子间亲核的攻击,形成酰胺化物中间体;生成的酰胺离解。研究了次级配位球相互作用对水合反应速率和收率的影响。能够与进入的水分子充当氢键受体的配体比非氢键配体产生更快的速率和更高的产率。较快的速率归因于水的氧键合至配位的腈,因此水的氢键促成的去质子化。拟议的氢键中间体的DFT计算支持这种解释。大多数均相催化剂不会水合氰醇,因为氰醇溶液中存在平衡量的氰化物。氰化物会使催化剂中毒。由于其由于次级配位球效应而增加的催化反应性,因此[Ru(η6-芳烃)Cl 2(P(NMe 2)3)]催化剂可显着提高氰醇
Arene–Ruthenium(II) Complexes Containing Inexpensive Tris(dimethylamino)phosphine: Highly Efficient Catalysts for the Selective Hydration of Nitriles into Amides
The catalytic hydration of nitriles into amides, in water under neutral conditions, has been studied using a series of arene-ruthenium(II) derivatives containing the commercially available and inexpensive ligand tris(dimethylamino)phosphine. Among them, best results were obtained with the complex [RuCl2(eta(6)-C6Me6)P(NMe2)(3)}], which selectively provided the desired amides in excellent yields and short times (TOF values up to 11 400 h(-1)). The process was operative with both aromatic, heteroaromatic, aliphatic, and alpha,beta-unsaturated organonitriles and showed a high functional group tolerance. The stability of [RuCl2(eta(6)-C6Me6)P(NMe2)(3)}] in water was evaluated, observing its progressive decomposition into the less-active dimethylamine nithenium(II) complex [RuCl2(eta(6)-C6Me6)(NHMe2)] by hydrolysis of the coordinated P(NMe2)(3) ligand. The X-ray crystal structure determination of the toluene complex [RuCl2(eta(6)-C6H5Me)P(NMe2)(3)}] is also included.
Synthesis and Characterization of the Trihalophosphine Compounds of Ruthenium [RuX<sub>2</sub>(η<sup>6</sup>-cymene)(PY<sub>3</sub>)] (X = Cl, Br, Y = F, Cl, Br) and the Related PF<sub>2</sub>(NMe<sub>2</sub>) and P(NMe<sub>2</sub>)<sub>3</sub> Compounds; Multinuclear NMR Spectroscopy and the X-ray Single Crystal Structures of [RuBr<sub>2</sub>(η<sup>6</sup>-cymene)(PF<sub>3</sub>)], [RuBr<sub>2</sub>(η<sup>6</sup>-cymene)(PF<sub>2</sub>{NMe<sub>2</sub>})], and [RuI<sub>2</sub>(η<sup>6</sup>-cymene)(P{NMe<sub>2</sub>}<sub>3</sub>)]
作者:Ahmed M. A. Boshaala、Stephen J. Simpson、Jochen Autschbach、Shaohui Zheng
DOI:10.1021/ic800611h
日期:2008.10.20
(31)P, and (19)F NMR spectra have been obtained where appropriate together with ((1)H-(1)H) correlation spectroscopy (COSY) and ((13)C-(1)H)-HETCORR spectra of selected compounds. The variation of (1)J((31)P-(19)F) with the nature of the auxiliary ligand (X) in the PF3 and PF2(NMe2) complexes has been examined both experimentally and computationally using a natural localized molecular orbital-natural bond