scholarly journals Insight into catalyst speciation and hydrogen co-evolution during enantioselective formic acid-driven transfer hydrogenation with bifunctional ruthenium complexes from multi-technique operando reaction monitoring

2019 ◽  
Vol 220 ◽  
pp. 45-57 ◽  
Author(s):  
Daniel B. G. Berry ◽  
Anna Codina ◽  
Ian Clegg ◽  
Catherine L. Lyall ◽  
John P. Lowe ◽  
...  
Keyword(s):  
Formic Acid ◽  
Maximum Rate ◽  
Hydrogen Transfer ◽  
Ruthenium Complexes ◽  
Transfer Hydrogenation ◽  
Reaction Monitoring ◽  
Optimal Conditions ◽  
Insight Into

Operando spectroscopy shows a transition from dehydrogenation to hydrogen transfer during the reaction, and allows measuring optimal conditions for maximum rate and efficiency.

scholarly journals Synthesis and structures of ruthenium–NHC complexes and their catalysis in hydrogen transfer reaction

2015 ◽  
Vol 11 ◽  
pp. 1786-1795 ◽  
Author(s):  
Chao Chen ◽  
Chunxin Lu ◽  
Qing Zheng ◽  
Shengliang Ni ◽  
Min Zhang ◽  
...  
Keyword(s):  
Hydrogen Transfer ◽  
Transfer Reaction ◽  
Ruthenium Complexes ◽  
Octahedral Geometry ◽  
Molecular Structures ◽  
Transfer Hydrogenation ◽  
Acetonitrile Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrogen Transfer Reaction

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.

Hydrogen transfer from formic acid to alkynes catalyzed by a diruthenium complex

2001 ◽  
Vol 79 (5-6) ◽  
pp. 915-921 ◽  
Author(s):  
Yuan Gao ◽  
Michael C Jennings ◽  
Richard J Puddephatt
Keyword(s):  
Carbon Dioxide ◽  
Formic Acid ◽  
Hydrogen Transfer ◽  
Hydrogen Donor ◽  
Transfer Hydrogenation ◽  
Stable Complex ◽  
Terminal Alkynes ◽  
Hydrogenation Catalysis ◽  
Diruthenium Complex ◽  
Electron Withdrawing Substituents

The diruthenium(0) complex [Ru2(µ-CO)(CO)4(µ-dppm)2] (1) (dppm = Ph2PCH2PPh2), is a catalyst for the transfer hydrogenation, using formic acid as hydrogen donor, of the alkynes PhCºCPh, PhCºCMe, EtCºCEt, and PrCºCPr but not of the terminal alkynes HCºCH, PhCºCH, BuCºCH, or the alkynes containing one or two electron-withdrawing substituents PhCºCCO2Me and MeO2CCtriple bondCCO2Me. In the successful reactions, the formic acid is first decomposed to carbon dioxide and hydrogen, which then hydrogenates the alkynes in a slower reaction. In the unsuccessful reactions, the decomposition of formic acid is strongly retarded by the alkyne. In the case with the alkyne PhCºCH, it is shown that the alkyne reacts with protonated 1 to give first [Ru2(µ-CPh=CH2)(CO)4(µ-dppm)2][HCO2], which then isomerizes to give the catalytically inactive, stable complex [Ru2(µ-CH=CHPh)(CO)4(µ-dppm)2][HCO2]. This complex has been structurally characterized and both of the µ-styrenyl complexes are shown to be fluxional in solution.Key words: ruthenium, hydrogenation, catalysis, binuclear..

scholarly journals New Bifunctional Bis(azairidacycle) with Axial Chirality via Double Cyclometalation of 2,2′-Bis(aminomethyl)-1,1′-binaphthyl

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1165
Author(s):  
Yasuhiro Sato ◽  
Yuichi Kawata ◽  
Shungo Yasui ◽  
Yoshihito Kayaki ◽  
Takao Ikariya
Keyword(s):  
Hydrogen Transfer ◽  
Bond Cleavage ◽  
Enantiomeric Excess ◽  
Transfer Hydrogenation ◽  
Catalyst Precursor ◽  
Asymmetric Catalysts ◽  
Axially Chiral ◽  
Diastereomeric Mixture ◽  
Raney Ni ◽  
Half Sandwich

As a candidate for bifunctional asymmetric catalysts containing a half-sandwich C–N chelating Ir(III) framework (azairidacycle), a dinuclear Ir complex with an axially chiral linkage is newly designed. An expedient synthesis of chiral 2,2′-bis(aminomethyl)-1,1′-binaphthyl (1) from 1,1-bi-2-naphthol (BINOL) was accomplished by a three-step process involving nickel-catalyzed cyanation and subsequent reduction with Raney-Ni and KBH4. The reaction of (S)-1 with an equimolar amount of [IrCl2Cp*]2 (Cp* = η5–C5(CH3)5) in the presence of sodium acetate in acetonitrile at 80 °C gave a diastereomeric mixture of new dinuclear dichloridodiiridium complexes (5) through the double C–H bond cleavage, as confirmed by 1H NMR spectroscopy. A loss of the central chirality on the Ir centers of 5 was demonstrated by treatment with KOC(CH3)3 to generate the corresponding 16e amidoiridium complex 6. The following hydrogen transfer from 2-propanol to 6 provided diastereomers of hydrido(amine)iridium retaining the bis(azairidacycle) architecture. The dinuclear chlorido(amine)iridium 5 can serve as a catalyst precursor for the asymmetric transfer hydrogenation of acetophenone with a substrate to a catalyst ratio of 200 in the presence of KOC(CH3)3 in 2-propanol, leading to (S)-1-phenylethanol with up to an enantiomeric excess (ee) of 67%.

Photocatalytic Transfer Hydrogenation in Water: Insight into Mechanism and Catalyst Speciation

2021 ◽  
Author(s):  
David M. Kaphan ◽  
Kelsey R. Brereton ◽  
Rachel C. Klet ◽  
Ryan J. Witzke ◽  
Alexander J. M. Miller ◽  
...  
Keyword(s):  
Transfer Hydrogenation ◽  
Insight Into

A CONVENIENT “HYDROGEN TRANSFER” HYDROGENATION OF TESTOSTERONE

1989 ◽  
Vol 21 (4) ◽  
pp. 515-517 ◽  
Author(s):  
Dimitris M. Spyriounis ◽  
George Ikonomidis ◽  
Vassilis J. Demopoulos
Keyword(s):  
Hydrogen Transfer ◽  
Transfer Hydrogenation

Novel ruthenium complexes bearing bipyridine-based and N-heterocyclic carbene-supported pyridine (NCN) ligands: the influence of ligands for catalytic transfer hydrogenation of ketones

2021 ◽  
Author(s):  
Akkharadet Piyasaengthong ◽  
Luke J Williams ◽  
Dmitry S Yufit ◽  
James William Walton
Keyword(s):  
Ruthenium Complexes ◽  
Metal Catalysts ◽  
Transfer Hydrogenation ◽  
Secondary Alcohols ◽  
Catalytic Transfer Hydrogenation ◽  
Homogeneous Catalysts ◽  
Catalytic Transfer

Transfer hydrogenation (TH) is a powerful synthetic tool in the production of secondary alcohols from ketones by using a non-H2 hydrogen source along with metal catalysts. Among homogeneous catalysts, Ru(II)...

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