13524-04-4Relevant articles and documents
Synthesis, Structure, Reactivity, and Catalytic Activity of Cyclometalated (Phosphine)- and (Phosphinite)ruthenium Complexes
Sun, Ruichen,Chu, Xiaodan,Zhang, Shaowei,Li, Tongyu,Wang, Zhuo,Zhu, Bolin
, p. 3174 - 3183 (2017)
Reactions of naphthyl- and o-methylphenyl-substituted phosphines with [RuCl2(p-cymene)]2 resulted in the corresponding phosphine-substituted ruthenium dichlorides (1a,b and 3). When the reactions of aryl-substituted phosphines or pho
Iridium(i) N-heterocyclic carbene complexes of benzimidazol-2-ylidene: Effect of electron donating groups on the catalytic transfer hydrogenation reaction
Guelcemal, Sueleyman,Goekce, Aytac Guerhan,Cetinkaya, Bekir
, p. 7305 - 7311 (2013)
Two new [Ir(NHC)(COD)Cl] (NHC = N-heterocyclic carbene; COD = 1,5-cyclooctadiene) iridium complexes (2a,b) have been prepared by the reaction of [Ir(COD)Cl]2 with in situ prepared NHC-Ag carbene transfer agents in dichloromethane at ambient temperature. They have been fully characterized by 1H, 13C NMR, and elemental analysis. X-ray diffraction studies on single crystals of 2a and 2b confirm the square planar geometry. Complexes of type [Ir(NHC)(CO)2Cl] [NHC = 1,3-diisopropyl(5,6- dimethyl)benzimidazol-2-ylidene] 3 were also synthesized to compare σ-donor/π-acceptor strength of NHC ligands. Transfer hydrogenation (TH) reactions of various aldehydes and ketones have been studied using complexes 2a and 2b as catalysts. The 5,6-dimethyl substituted iridium complex (2b) showed the highest catalytic activity for the TH reaction.
Cyclometalated ruthenium(II) complexes as highly active transfer hydrogenation catalysts
Baratta, Walter,Da Ros, Paolo,Del Zotto, Alessandro,Sechi, Alessandra,Zangrando, Ennio,Rigo, Pierluigi
, p. 3584 - 3588 (2004)
Quantitative conversion: Reaction of the 14-electron complex [RuCl 2{(2,6-Me2C6H3)PPh2} 2] with CH2O in the presence of NEt3 gave a five-coordinate cyclometalated complex with a δ-agostic interaction of one ortho-methyl group (see X-ray crystal structure), Displacement of one phosphane group with 2-(amino-methyl)pyridine gave a highly active catalyst for the quantitative conversion of ketones into alcohols.
Pure phosphotriesters as versatile ligands in transition metal catalysis: efficient hydrosilylation of ketones and diethylzinc addition to aldehydes
Bouhachicha,Ngo Ndimba,Roisnel,Lalli,Argouarch
, p. 4767 - 4770 (2017)
This work aims to highlight the underrated role played by pure phosphotriester (or phosphate) ligands in catalysis, when compared to other phosphorus-containing donors such as phosphane oxides or phosphites. To probe this and to enlarge the very narrow catalytic scope of these Lewis bases, easily accessible mono- and bidentate phosphotriesters were tested as donors in two important transition metal-based catalytic transformations: the zinc-catalyzed hydrosilylation of ketones and the titanium-promoted diethylzinc addition to aldehydes. In both cases, the reactions were successful and the corresponding alcohols were obtained in high yields.
Uncatalyzed hydrogen-transfer reductions of aryl ketones
Srinivasan,Manisankar
, p. 1338 - 1347 (2011)
A simple, convenient, and environmentally benign procedure has been developed for exclusive reduction of aryl ketones by hydrogen transfer with sec-BuOH as hydrogen donor in the presence of KOH without supercritical conditions, ligands, and any catalytic utility.
Practical approach to the Meerwein-Ponndorf-Verley reduction of carbonyl substrates with new aluminum catalysts
Ooi, Takashi,Ichikawa, Hayato,Maruoka, Keiji
, p. 3610 - 3612 (2001)
Simple mixing of Al(OiPr)3 with the requisite ligand 1 in CH2Cl2 at room temperature smoothly generates the new, powerful aluminum catalyst 2, which efficiently catalyzes Meerwein-Ponndorf-Verley (MPV) reduction of various carbonyl substrates under mild conditions (see scheme). Scale-up experiments highlight the potential of the new MPV reduction procedure for practical use.
Synthesis of 2-aminomethylpiperidine ruthenium(II) phosphine complexes and their applications in transfer hydrogenation of aryl ketones
Tuerkmen, Hayati
, p. 731 - 735 (2012)
The complex trans,cis-[RuCl2(PPh3)2(ampi)] (2) was prepared by reaction of RuCl2(PPh3)3 with 2-aminomethylpiperidine(ampi) (1). [RuCl2(PPh 2(CH2)nPPh2)(ampi) (n = 3, 4, 5)] (3-5) were synthesized by displacement of two PPh3 with chelating phosphine ligands. All complexes (2-5) were characterized by 1 H, 13C, 31P NMR, IR and UV-visible spectroscopy and elemental analysis. They were found to be efficient catalysts for transfer hydrogen reactions. Copyright
Mechanistic investigation of the hydrogenation of ketones catalyzed by a ruthenium(II) complex featuring an N-heterocyclic carbene with a tethered primary amine donor: Evidence for an inner sphere mechanism
O, Wylie W.N.,Lough, Alan J.,Morris, Robert H.
, p. 1236 - 1252 (2011)
The complex [Ru(p-cymene)(m-CH2NH2)Cl]PF6 (1) catalyzes the H2-hydrogenation of ketones in basic THF under 25 bar of H2 at 50 °C with a turnover frequency (TOF) of up to 461 h-1 and a maximum conversion of 99%. When the substrate is acetophenone, the TOF decreases significantly as the catalyst to substrate ratio is increased. The rate law was then determined to be rate = k H[Ru]tot[H2]/(1 + Keq[ketone]), and [1] is equal to [Ru]tot if catalyst decomposition does not occur. This is consistent with the heterolytic splitting of dihydrogen at the active ruthenium species as the rate-determining step. In competition with this reaction is the reversible addition of acetophenone to the active species to give an enolate complex. The transfer to the ketone of a hydride and proton equivalent that are produced in the heterolytic splitting reaction yields the product in a fast, low activation barrier step. The kinetic isotope effect was measured using D2 gas and acetophenone-d3, and this gave values (kH/kD) of 1.33 ± 0.15 and 1.29 ± 0.15, respectively. The ruthenium hydride complex [Ru(p-cymene)(m-CH 2NH2)H]PF6 (2) was prepared, as this was postulated to be a crucial intermediate in the outer-sphere bifunctional mechanism. This is inactive under catalytic conditions unless it is activated by a base. DFT computations suggest that the energy barriers for the addition of dihydrogen, heterolytic splitting of dihydrogen, and concerted transfer of H+/H- to the ketone for the outer-sphere mechanism would be respectively 18.0, 0.2, and 33.5 kcal/mol uphill at 298 K and 1 atm. On the other hand, the energy barriers for an inner-sphere mechanism involving the decoordination of the amine group of the NHC ligand, the heterolytic splitting of dihydrogen across a Ru-O(alkoxide) bond, and hydride migration to the coordinated ketone, are respectively 15.5, 17.5, and 15.6 kcal/mol uphill at 298 K and 1 atm. This is more consistent with the experimental observation that the heterolytic splitting of dihydrogen is the turnover-limiting step. This was confirmed by showing that an analogous complex with a tethered teritiary amine group has comparable activity for the H2-hydrogenation of acetophenone. The related complex [Os(p-cymene)(m-CH2NH 2)Cl]PF6 (6) was synthesized by a transmetalation reaction with [Ni(m-CH2NH2)2](PF6) 2 (5) and [Os(p-cymene)Cl2]2, and its catalytic activity toward hydrogenation of acetophenone was also investigated.
Enhancing cofactor regeneration of cyanobacteria for the light-powered synthesis of chiral alcohols
Fan, Jianhua,Zhang, Yinghui,Wu, Ping,Zhang, Xiaoyan,Bai, Yunpeng
, (2021/11/24)
Cyanobacteria Synechocystis sp. PCC 6803 was exploited as green cell factory for light-powered asymmetric synthesis of aromatic chiral alcohols. The effect of temperature, light, substrate and cell concentration on substrate conversions were investigated. Under the optimal condition, a series of chiral alcohols were synthesized with conversions up to 95% and enantiomer excess (ee) > 99%. We found that the addition of Na2S2O3 and Angeli's Salt increased the NADPH content by 20% and 25%, respectively. As a result, the time to reach 95% substrate conversion was shortened by 12 h, which demonstrated that the NADPH regeneration and hence the reaction rates can be regulated in cyanobacteria. This blue-green algae based biocatalysis showed its potential for chiral compounds production in future.
Cinchona-Alkaloid-Derived NNP Ligand for Iridium-Catalyzed Asymmetric Hydrogenation of Ketones
Zhang, Lin,Zhang, Ling,Chen, Qian,Li, Linlin,Jiang, Jian,Sun, Hao,Zhao, Chong,Yang, Yuanyong,Li, Chun
supporting information, p. 415 - 419 (2022/01/12)
Most ligands applied for asymmetric hydrogenation are synthesized via multistep reactions with expensive chemical reagents. Herein, a series of novel and easily accessed cinchona-alkaloid-based NNP ligands have been developed in two steps. By combining [Ir(COD)Cl]2, 39 ketones including aromatic, heteroaryl, and alkyl ketones have been hydrogenated, all affording valuable chiral alcohols with 96.0-99.9% ee. A plausible reaction mechanism was discussed by NMR, HRMS, and DFT, and an activating model involving trihydride was verified.
