1737-26-4Relevant academic research and scientific papers
Asymmetric hydrogenation of aromatic ketones catalyzed by (1S,2S)-DPEN-modified Ru-PPh3/γ-Al2O3 catalyst
Tang, Bo,Xiong, Wei,Liu, De-Rong,Jia, Yun,Wang, Jin-Bo,Chen, Hua,Li, Xian-Jun
, p. 1397 - 1401 (2008)
The asymmetric hydrogenations of acetophenone and its derivatives over the (1S,2S)-DPEN-modified Ru-PPh3/γ-Al2O3 were investigated. The effects of reaction conditions on the asymmetric hydrogenation of acetophenone are dis
Synthesis and structures of ruthenium-NHC complexes and their catalysis in hydrogen transfer reaction
Chen, Chao,Lu, Chunxin,Zheng, Qing,Ni, Shengliang,Zhang, Min,Chen, Wanzhi
, p. 1786 - 1795 (2015)
Ruthenium complexes [Ru(L1)2(CH3CN)2](PF6)2 (1), [RuL1(CH3CN)4](PF6)2 (2) and [RuL2(CH3CN)3](PF6)2 (3) (L1= 3-methyl- 1-(pyrimidine-2-yl)imidazolylidene, L2 = 1,3-bis(pyridin-2-ylmethyl)benzimidazolylidene) were obtained through a transmetallation reaction of the corresponding nickel-NHC complexes with [Ru(p-cymene)2Cl2]2 in refluxing acetonitrile solution. The crystal structures of three complexes determined by X-ray analyses show that the central Ru(II) atoms are coordinated by pyrimidine- or pyridine-functionalized N-heterocyclic carbene and acetonitrile ligands displaying the typical octahedral geometry. The reaction of [RuL1(CH3CN)4](PF6)2 with triphenylphosphine and 1,10-phenanthroline resulted in the substitution of one and two coordinated acetonitrile ligands and afforded [RuL1(PPh3)(CH3CN)3](PF6)2 (4) and [RuL1(phen)(CH3CN)2](PF6)2 (5), respectively. The molecular structures of the complexes 4 and 5 were also studied by X-ray diffraction analysis. These ruthenium complexes have proven to be efficient catalysts for transfer hydrogenation of various ketones.
Hydrogenation of aryl ketones using palladium nanoparticles on single-walled carbon nanotubes in an ionic liquid
Lee, Jae Kwan,Kim, Mahn-Joo
, p. 499 - 501 (2011)
Single-walled carbon nanotubes (SWNTs) are used as supporting materials for palladium (Pd) nanoparticles generated in situ in ionic liquid (IL); Pd nanocatalysts on SWNTs exhibit superior reactivity for hydrogenation of aryl ketones in IL under mild conditions (1 atm of H2 (g) and room temperature) and can be reused above 10 times without any loss of catalytic activity.
Cationic iron(II) complexes of the mixed cyclopentadienyl (Cp) and the N-heterocyclic carbene (NHC) ligands as effective precatalysts for the hydrosilylation of carbonyl compounds
Kumar, Dharmendra,Prakasham,Bheeter, Linus Paulin,Sortais, Jean-Baptiste,Gangwar, Manoj,Roisnel, Thierry,Kalita, Alok Ch,Darcel, Christophe,Ghosh, Prasenjit
, p. 81 - 87 (2014)
A series of iron(II) complexes of N-heterocyclic carbene ligands was synthesized and fully structurally characterized. Specifically, the benzimidazole based {Cp[1,3-di-R-benzimidazol-2-ylidene]-Fe(CO)2}I [R = Et (1b), i-Pr (2b) and n-Bu (3b)] a
N-heterocyclic carbenes of iridium(I): Ligand effects on the catalytic activity in transfer hydrogenation
Zinner, Sandra C.,Rentzsch, Christoph F.,Herdtweck, Eberhardt,Herrmann, Wolfgang A.,Kuehn, Fritz. E.
, p. 7055 - 7062 (2009)
New Ir-NHC complexes based on different heterocyclic moieties like imidazole, benzimidazole and imidazolidine are presented and tested in transfer hydrogenation catalysis. A broad range of steric and electronic properties of NHC ligands is covered to give an idea for catalyst design from the experimental point of view.
Reductions with Organosilanes. Primary and Secondary Isotope Effects in the Reduction of p-Trifluoromethylacetophenone with Organosilanes.
Smonou, Ioulia
, p. 2071 - 2074 (1994)
The kinetic primary and secondary isotope effects in the reduction of p-trifluoromethylacetophenone with triethylsilane-etherated boron trifluoride were studied.
Highly electron-rich pincer-type iron complexes bearing innocent bis(metallylene)pyridine ligands: Syntheses, structures, and catalytic activity
Gallego, Daniel,Inoue, Shigeyoshi,Blom, Burgert,Driess, Matthias
, p. 6885 - 6897 (2014)
The first neutral bis(metallylene)pyridine pincer-type [ENE] ligands (E = SiII, GeII) were synthesized, and their coordination chemistry and reactivity toward iron was studied. First, the unprecedented four-coordinate complexes κ2E,E'-[ENE]FeCl2 were isolated. Unexpectedly and in contrast to other related pyridine-based pincer-type Fe(II) complexes, the N atom of pyridine is reluctant to coordinate to the Fe(II) site due to the enhanced α-donor strength of the E atoms, which disfavors this coordination mode. Subsequent reduction of κ2Si,Si'-[SiNSi]FeCl2 with KC8 in the presence of PMe3 or direct reaction of the [ENE] ligands using Fe(PMe3)4 produced the highly electron-rich iron(0) complexes [ENE]Fe(PMe3)2. The reduction of the iron center substantially changes its coordination features, as shown by the results of a single-crystal X-ray diffraction analysis of [SiNSi]Fe(PMe3)2. The iron center, in the latter, exhibits a pseudosquare pyramidal (PSQP) coordination environment, with a coordinative (pyridine)-Rfnet→Fe bond, and a trimethylphosphine ligand occupying the apical position. This geometry is very unusual for Fe(0) low-spin complexes, and variable-temperature 1H and 31P NMR spectra of the [ENE]Fe(PMe3)2 complexes revealed that they represent the first examples of configurationally stable PSQP-coordinated Fe(0) complexes: even after heating at 70 °C for >7 days, no changes are observed. The substitution reaction of [ENE]Fe(PMe3)2 with CO resulted in the isolation of [ENE]Fe(CO)2 and the hitherto unknown κ2E,E'-[ENE]Fe(CO)2L (L = CO, PMe3) complexes. All complexes were fully characterized (NMR, MS, XRD, IR, and 57Fe M?ssbauer spectroscopy), showing the highest electron density on the iron center for pincer-type complexes reported to date. DFT calculations and 57Fe M?ssbauer spectroscopy confirmed the innocent behavior of these ligands. Moreover, preliminary results showed that these complexes can serve as active precatalysts for the hydrosilylation of ketones.
Simple Ligand Modifications with Pendent OH Groups Dramatically Impact the Activity and Selectivity of Ruthenium Catalysts for Transfer Hydrogenation: The Importance of Alkali Metals
Moore, Cameron M.,Bark, Byongjoo,Szymczak, Nathaniel K.
, p. 1981 - 1990 (2016)
Remarkable differences in selectivity and activity for ruthenium-catalyzed transfer hydrogenation are described that are imparted by pendent OH groups. Kinetic experiments, as well as the study of control complexes devoid of OH groups, reveal that the pendent OH groups serve to orient the ketone substrate through ion pairing with an alkali metal under basic conditions. The deprotonation of the OH groups was found to modulate the electronics at the metal center, providing a more electron rich ruthenium center. The effects of the ion pairing between alkali metals and the pendent alkoxide groups were highlighted by demonstrating chemoselective transfer hydrogenation of ketones in the presence of olefins. The results illustrate that a simple ligand modification (installation of OH groups) imparts dramatic changes to catalysis. Pendent OH groups turn on catalysis through electronic perturbations at the metal site under basic conditions and can also change the mechanism of catalysis, the latter of which can be used to promote chemoselective reductions.
Hydrosilylation of Aldehydes and Ketones Catalyzed by a 2-Iminopyrrolyl Alkyl-Manganese(II) Complex
Cruz, Tiago F. C.,Veiros, Luís F.,Gomes, Pedro T.
supporting information, p. 1195 - 1206 (2022/01/11)
A well-defined and very active single-component manganese(II) catalyst system for the hydrosilylation of aldehydes and ketones is presented. First, the reaction of 5-(2,4,6-iPr3C6H2)-2-[N-(2,6-iPr2C6H3)formimino]pyrrolyl potassium (KL) and [MnCl2(Py)2] afforded the binuclear 2-iminopyrrolyl manganese(II) pyridine chloride complex [Mn2{κ2N,N′-5-(2,4,6-iPr3C6H2)-NC4H2-2-C(H)═N(2,6-iPr2C6H3)}2(Py)2(μ-Cl)2] 1. Subsequently, the alkylation reaction of complex 1 with LiCH2SiMe3 afforded the respective (trimethylsilyl)methyl-Mn(II) complex [Mn{κ2N,N′-5-(2,4,6-iPr3C6H2)-NC4H2-2-C(H)═N(2,6-iPr2C6H3)}(Py)CH2SiMe3] 2 in a good yield. Complexes 1 and 2 were characterized by elemental analysis, 1H NMR spectroscopy, Evans' method, FTIR spectroscopy, and single-crystal X-ray diffraction. While the crystal structure of complex 1 has been identified as a binuclear entity, in which the Mn(II) centers present pentacoordinate coordination spheres, that of complex 2 corresponds to a monomer with a distorted tetrahedral coordination geometry. Complex 2 proved to be a very active precatalyst for the atom-economic hydrosilylation of several aldehydes and ketones under very mild conditions, with a maximum turnover frequency of 95 min-1, via a silyl-Mn(II) mechanistic route, as asserted by a combination of experimental and theoretical efforts, the respective silanes were cleanly converted to the respective alcoholic products in high yields.
Regiodivergent Reductive Opening of Epoxides by Catalytic Hydrogenation Promoted by a (Cyclopentadienone)iron Complex
Tadiello, Laura,Gandini, Tommaso,Stadler, Bernhard M.,Tin, Sergey,Jiao, Haijun,de Vries, Johannes G.,Pignataro, Luca,Gennari, Cesare
, p. 235 - 246 (2022/01/03)
The reductive opening of epoxides represents an attractive method for the synthesis of alcohols, but its potential application is limited by the use of stoichiometric amounts of metal hydride reducing agents (e.g., LiAlH4). For this reason, the corresponding homogeneous catalytic version with H2 is receiving increasing attention. However, investigation of this alternative has just begun, and several issues are still present, such as the use of noble metals/expensive ligands, high catalytic loading, and poor regioselectivity. Herein, we describe the use of a cheap and easy-To-handle (cyclopentadienone)iron complex (1a), previously developed by some of us, as a precatalyst for the reductive opening of epoxides with H2. While aryl epoxides smoothly reacted to afford linear alcohols, aliphatic epoxides turned out to be particularly challenging, requiring the presence of a Lewis acid cocatalyst. Remarkably, we found that it is possible to steer the regioselectivity with a careful choice of Lewis acid. A series of deuterium labeling and computational studies were run to investigate the reaction mechanism, which seems to involve more than a single pathway.
