An outstanding catalyst for asymmetric transfer hydrogenation in aqueous solution and formic acid/triethylamine

Matharu, Daljit S.; Morris, David J.; Clarkson, Guy J.; Wills, Martin

doi:10.1039/b606288a

Cited by 133 publications

(53 citation statements)

References 63 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…8,9 Recently, NADH/NAD + regeneration under mild conditions in aqueous media has been studied. 10,11 Significant attention has focused on transition metal complexes as catalysts for regeneration of NADH via hydrogenation 10 (H 2 ) or transfer hydrogenation using 2-propanol, 12 glycerol, 13 phosphate, 14 formic acid together with a base, 15 or formate 11 as the hydride source in water. Some Ru II , 16 Rh III , 17,18 and Ir III 19 halfsandwich complexes can catalyze the hydrogenation or transfer hydrogenation of ketones, 20 aldehydes, 21 imines, 22 or carbon dioxide, 23 although the optimum conditions for the reactions are usually not biologically relevant.…”

Section: ■ Introductionmentioning

confidence: 99%

Improved Catalytic Activity of Ruthenium–Arene Complexes in the Reduction of NAD⁺

et al. 2012

Self Cite

View full text Add to dashboard Cite

A series of neutral Ru II half-sandwich complexes of the type [(η 6 -arene)Ru(N,N′)Cl] where the arene is para-cymene (p-cym), hexamethylbenzene (hmb), biphenyl (bip), or benzene (bn) and N,N′ is N-(2-aminoethyl)-4-(trifluoromethyl)benzenesulfonamide (TfEn), N-(2-aminoethyl)-4-toluenesulfonamide (TsEn), or N-(2-aminoethyl)-methylenesulfonamide (MsEn) were synthesized and characterized. X-ray crystal structures of [(p-cym) The coordination of formate and subsequent CO 2 elimination to generate the hydride were modeled computationally by density functional theory (DFT). CO 2 elimination occurs via a two-step process with the coordinated formate first twisting to present its hydrogen toward the metal center. The computed barriers for CO 2 release for arene = benzene follow the order MsEn > TsEn > TfEn, and for the MsEn system the barrier followed bn < hmb, both consistent with the observed rates. The effect of methanol on transfer hydrogenation rates in aqueous solution was investigated. A study of pH dependence of the reaction in D 2 O gave the optimum pH* as 7.2 with a TOF of 1.58 h −1 for 2. The series of compounds reported here show an improvement in the catalytic activity by an order of magnitude compared to the ethylenediamine analogues. ■ INTRODUCTIONThe coenzyme nicotinamide adenine dinucleotide (NAD + ) and its reduced form 1,4-NADH have crucial roles in many cellular metabolic processes such as regulation of energy metabolism, antioxidative function, DNA repair and transcription, immunological functions, and cell death. 1 The coenzymes are involved in many other processes, acting as substrates and cofactors for enzymes such as NAD + ligases, oxidoreductases, polymerases, and deacetylases involved in biosynthesis.The coenzymes NAD + /NADH have been studied intensively during the past few years. It has been demonstrated that changes in metabolism result in fluctuations in the ratio NAD + / NADH or, conversely, changes in the ratio can produce metabolic changes. 2 In some cases alterations in the cellular redox status have been shown to play an important role in cell death, and therefore the coenzymes have become possible drug targets for chronic or autoimmune diseases such as Parkinson's, hepatitis C, diabetic vascular dysfunction, hyperglycemia, and cancer. 3 The concentration of NAD + and the ratio NAD + /NADH have been shown to be very important for cancer cells. On the one hand, due to their active metabolism, cancer cells generate high levels of oxidizing species and, therefore, they are under constant oxidative stress. 4 This makes cancer cells more dependent on redox regulatory systems and more sensitive to variations in the NAD + /NADH ratio. On the other hand, NAD + is required as a substrate for many enzymatic reactions such as ADP-ribosylation, which is crucial for genome stability and DNA repair. 3 Due to the up-regulation of some enzymes required for the biosynthesis of NAD + in cancer cells, a

show abstract

Section: ■ Introductionmentioning

confidence: 99%

Improved Catalytic Activity of Ruthenium–Arene Complexes in the Reduction of NAD⁺

et al. 2012

Self Cite

View full text Add to dashboard Cite

show abstract

“…[1] The transition-metal-based enantioselective hydrogenation or transfer hydrogenation of ketones in organic solvents [2][3][4][5][6][7][8][9][10] as well as in aqueous solutions [11][12][13][14][15][16][17][18][19][20][21] is one of the most commonly used synthetic approaches. Biotransformations of organic substrates by various enzymes have also found widespread applications, particularly because of their capability to efficiently perform enantioselective transformations.…”

Section: Introductionmentioning

confidence: 99%

Water‐Soluble Phenanthroline Complexes of Rhodium, Iridium and Ruthenium for the Regeneration of NADH in the Enzymatic Reduction of Ketones

2007

View full text Add to dashboard Cite

show abstract

“…Due to its difficult purification, the ligand L22 was replaced by another water-soluble ligand L23, and its complex with [C5Me5RhCl2]2 was active for the ATH of -bromomethylaromatic ketones, besides ringsubstituted acetophenones, and bicyclic ketones (L. Li et al, 2007). The tethered Rh complex C20 reported by Wills acts as a very productive catalyst for aqueous-reduction as it continues to turnover a reaction at low loadings, even at 0.01 mol%, typically associated with the best H2-hydrogenation catalysts, without any decrease in the enantioselectivity (Matharu et al, 2006). The chiral aqua Ir(III)-complex C21 bearing non-sulfonated diamine was shown to be very flexible in the ATH of -cyano-and -nitroacetophenones as the reaction can be conducted at pH 2 (formic acid) as well as at pH 5.5 (HCO2Na) in a watermethanol system without affecting the selectivity (Vázquez-Villa et al, 2011) (Fig.…”

Section: Hydrogenation and Transfer Hydrogenation In Water And Ionic mentioning

confidence: 99%

Asymmetric Hydrogenation and Transfer Hydrogenation of Ketones

Štefane¹,

Požgan²

2012

Hydrogenation

View full text Add to dashboard Cite

An outstanding catalyst for asymmetric transfer hydrogenation in aqueous solution and formic acid/triethylamine

Abstract: A Rh/tetramethylcyclopentadienyl complex containing a tethered functionality has been demonstrated to give excellent results in the asymmetric transfer hydrogenation of ketones in both aqueous and formic acid/triethylamine media.

Cited by 133 publications

References 63 publications

Improved Catalytic Activity of Ruthenium–Arene Complexes in the Reduction of NAD⁺

Improved Catalytic Activity of Ruthenium–Arene Complexes in the Reduction of NAD⁺

Water‐Soluble Phenanthroline Complexes of Rhodium, Iridium and Ruthenium for the Regeneration of NADH in the Enzymatic Reduction of Ketones

Asymmetric Hydrogenation and Transfer Hydrogenation of Ketones

Contact Info

Product

Resources

About

An outstanding catalyst for asymmetric transfer hydrogenation in aqueous solution and formic acid/triethylamine

Abstract: A Rh/tetramethylcyclopentadienyl complex containing a tethered functionality has been demonstrated to give excellent results in the asymmetric transfer hydrogenation of ketones in both aqueous and formic acid/triethylamine media.

Cited by 133 publications

References 63 publications

Improved Catalytic Activity of Ruthenium–Arene Complexes in the Reduction of NAD+

Improved Catalytic Activity of Ruthenium–Arene Complexes in the Reduction of NAD+

Water‐Soluble Phenanthroline Complexes of Rhodium, Iridium and Ruthenium for the Regeneration of NADH in the Enzymatic Reduction of Ketones

Asymmetric Hydrogenation and Transfer Hydrogenation of Ketones

Contact Info

Product

Resources

About

Improved Catalytic Activity of Ruthenium–Arene Complexes in the Reduction of NAD⁺

Improved Catalytic Activity of Ruthenium–Arene Complexes in the Reduction of NAD⁺