Transfer Hydrogenation Of Aromatic Ketones Research Articles

Asymmetric Transfer Hydrogenation of Aromatic Ketones in Water using a Polymer‐Supported Chiral Catalyst Containing a Hydrophilic Pendant Group

AbstractHydrophilic polymers having pendant groups of carboxylates or sulfonates have been used as a polymer support for chiral 1,2‐diamine monosulfonamides. The polymeric chiral complex prepared from the polymer‐supported chiral ligand with ruthenium dichloride⋅p‐cymene was used in the asymmetric transfer hydrogenation of prochiral ketones in water. The balance between hydrophilicity and hydrophobicity of the polymer support influenced both the reactivity and the enantioselectivity of the reaction in water. The chiral polymeric complex having a quaternary ammonium salt structure as the pendant group worked well in water. In most cases the polymer‐supported catalyst having a quaternary ammonium sulfonate pendant group showed superior enantioselectivity compared to the corresponding non‐supported model catalyst in the solution system. The polymeric catalysts can be reused without loss of catalytic activity.

Facile synthesis of a mesoporous silica-supported catalyst for Ru-catalyzed transfer hydrogenation of ketones

A convenient method for preparation of a mesoporous silica-supported chiral catalyst by postgrafting a homogeneous catalyst on SBA-15 was developed and its application in the asymmetric transfer hydrogenation of aromatic ketones was investigated.

Chiral sulfur-containing ligands for iridium(I)-catalyzed asymmetric transfer hydrogenation of aromatic ketones

New efficient catalyst systems, coupled with IrCl(COD)PPh 3 and chiral [SNNS]-type ligands, were employed in the asymmetric transfer hydrogenation of aromatic ketones under mild reaction conditions. The corresponding optically active alcohols were obtained in high yield and good to excellent enantioselectivities (up to 96% ee). The chiral Ir(I) complexes with the ligands of [SNNS]-type were also prepared and characterized, which showed good enantioselectivity and high activity. The reactions can be performed in air and the catalytic experiments are greatly simplified.

Synthesis of novel chiral macrocyclic ONNO-type ligands and use in asymmetric transfer hydrogenation

The interaction of 1,3-bis(2-formylphenoxy)-2-propanol with chiral 1,2-diaminocyclohexane gave novel chiral macrocyclic ONNO-type ligands which were fully characterized by IR, NMR, MS and CD. The catalyst systems generated in situ from the chiral cyclic ONNO ligands and the iridium hydride complex [IrHCl 2(COD)] 2 have been used for the first time in the asymmetric transfer hydrogenation of aromatic ketones using 2-propanol as a source of hydrogen, giving the corresponding optically active alcohols with high chemical yields and good to excellent enantioselectivities (up to 92% ee). The reactions can be performed in air and the catalytic experiments are greatly simplified.

Novel chiral tetraaza ligands: synthesis and application in asymmetric transfer hydrogenation of ketones

Novel chiral tetraaza ligands, N 1, N 2-bis(2-(piperidin-1-yl)benzylidene)cyclohexane-1,2-diamine 1 and N 1, N 2-bis(2-(piperidin-1-yl)benzyl)cyclohexane-1,2-diamine 2, have been synthesized and fully characterized by analytical and spectroscopic methods. The structure of ( R, R)- 1 has been established by X-ray crystallography. Asymmetric transfer hydrogenation of aromatic ketones with the catalysts prepared in situ from [IrHCl 2(COD)] 2 and the chiral tetraaza ligands in 2-propanol gave the corresponding optically active secondary alcohols in high conversions and good ees (up to 91%) under mild reaction conditions.

Synthesis of polymers containing chiral 1,2-diamine derivatives and their application to asymmetric reactions

Abstract Polymer-supported chiral 1,2-diamine derivatives have been prepared. The polymers containing free 1,2-diamine moiety were applied to enantioselective hydrogenation catalyst by combination with RuCl2-BINAP complex. Asymmetric hydrogenation of aromatic ketones was performed by means of the polymeric catalyst derived from these polymers to give the chiral secondary alcohols with high ee in quantitative conversion. The polymers containing 1,2-diamine monosulfonamide were applied to enantioselective transfer hydrogenation catalyst by combination with RuCl2-p-cymene complex. Asymmetric transfer hydrogenation of aromatic ketones was performed by means of the polymeric catalyst to afford the chiral secondary alcohols. A high level of enantioselectivities up to 99 % ee was attained in neat water by using the polymeric catalyst prepared from quaternary ammonium salt-type polymer support.

Highly Efficient Chiral PNNP Ligand for Asymmetric Transfer Hydrogenation of Aromatic Ketones in Water.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Selective Transfer Hydrogenation of Carbonyl Compounds by Ruthenium Nanoclusters Supported on Alkali‐Exchanged Zeolite Beta

AbstractSelective transfer hydrogenation of aromatic ketones and β‐keto esters to the corresponding alcohols was achieved by using ruthenium nanoclusters supported on alkali‐exchanged zeolite beta catalyst. The high activity and selectivity of the catalyst is due to the presence of highly dispersed ruthenium clusters in combination with the large number of Brønsted acidic sites of zeolite.

The Hydrogenation/Transfer Hydrogenation Network: Asymmetric Hydrogenation of Ketones with Chiral η6-Arene/N-Tosylethylenediamine−Ruthenium(II) Catalysts

Chiral eta6-arene/N-tosylethylenediamine-Ru(II) complexes, known as excellent catalysts for asymmetric transfer hydrogenation of aromatic ketones in basic 2-propanol, can be used for asymmetric hydrogenation using H2 gas. Active catalysts are generated from RuCl[(S,S)-TsNCH(C6H5)CH(C6H5)NH2](eta6-p-cymene) in methanol, but not 2-propanol, or by combination of Ru[(S,S)-TsNCH(C6H5)CH(C6H5)NH](eta6-p-cymene) and CF3SO3H or other non-nucleophilic acids. This method allows, for the first time, asymmetric hydrogenation of simple ketones under acidic conditions. Hydrogenation of base-sensitive 4-chromanone and its derivatives with the S,S catalyst proceeds in methanol with a substrate-to-catalyst molar ratio of 1000-3000 (10 atm) to 7000 (100 atm), giving (S)-4-chromanols with 97% ee quantitatively. The reaction can be achieved even on a 2.4 kg scale. The mechanistic rationale for the catalytic efficiency is presented.

Novel recoverable catalysts for asymmetric transfer hydrogenation

9-Amino(9-deoxy)epiquinine and 9-amino(9-deoxy)epicinchonine were applied in asymmetric transfer hydrogenation of aromatic ketones in both iridium and rhodium catalytic systems using i-propanol as the hydrogen source. Good to excellent conversions and enantioselectivities were observed with a variety of aromatic ketones. Moreover, the Ir complex and Rh complex of 9-amino(9-deoxy)cinchonine were recovered in high yields with dilute hydrochloric acid. The enantioselectivity of 1-phenylethanol was nearly maintained after six cycles.

Highly efficient chiral PNNP ligand for asymmetric transfer hydrogenation of aromatic ketones in water

Chiral PNNP ligand II and [IrHCl 2(COD)] 2 were applied for the first time in the asymmetric transfer hydrogenation of aromatic ketones with HCOONa in water, giving the corresponding optical alcohols in high yield and excellent enantioselectivity (up to 99% ee). Particularly, the reduction of propiophenone proceeded smoothly at a substrate to catalyst molar ratio of 8000, without compromising the ee values obtained.

Design of novel polymer-supported chiral catalyst for asymmetric transfer hydrogenation in water

New polymer-supported chiral sulfonamides containing sulfonated pendant group have been synthesized. Chiral catalyst prepared from the new polymer-support is more effective for asymmetric transfer hydrogenation of aromatic ketones in water compared to that prepared from conventional polystyrene-support. Polymer-supported catalysts containing quaternary ammonium salt as a pendant increased not only the reactivity but also the enantioselectivity in asymmetric transfer hydrogenation in water. Moreover, this type of polymer can be reused without loss of the catalytic activity.

A Remarkably Effective Catalyst for the Asymmetric Transfer Hydrogenation of Aromatic Ketones in Water and Air.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Preparation of Polymer‐Supported Ru‐TsDPEN Catalysts and Use for Enantioselective Synthesis of (S)‐Fluoxetine.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Asymmetric Reduction of Ketones Catalyzed by a Polymeric Chiral Ru Complex

Two polystyrene-supported chiral ligands 1 and 2, based on (1S,2S)-N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine (TsDPEN), were prepared from sodium 4-hydroxybenzenesulfonate dihydrate in seven and eight steps, respectively. The catalytic properties of their Ru complexes prepared in situ were examined for the asymmetric transfer hydrogenation of aromatic ketones with formic acid-triethylamine azeotrope as the hydrogen source to exhibit the high catalytic activities and enantioselectivities. This reduction protocol also displayed excellent chemoselectivities: the keto-carbonyl group was reduced selectively under these reaction conditions whereas the adjacent ester, amide, or cyano groups remained intact. The immobilized catalyst was easily recovered by simple filtration and subsequent washing with dichloromethane, and was reused without a significant drop in enantioselectivity. The resulting optically active alcohols are known to be appropriate intermediates for the synthesis of (S)-fluoxetine, which is an important antidepressant.

Highly Efficient Iridium Catalyst for Asymmetric Transfer Hydrogenation of Aromatic Ketones under Base‐Free Conditions.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Insight into and Practical Application of pH‐Controlled Asymmetric Transfer Hydrogenation of Aromatic Ketones in Water

Insight into and Practical Application of pH‐Controlled Asymmetric Transfer Hydrogenation of Aromatic Ketones in Water

Insight into and Practical Application of pH‐Controlled Asymmetric Transfer Hydrogenation of Aromatic Ketones in Water

Eine viel schnellere, enantioselektivere und produktivere Katalyse der asymmetrischen Transferhydrierung aromatischer Ketone gelingt mit dem Noyori-Ikariya-Ru-(Ts-dpen)-Katalysator, wenn er in Wasser bei nahezu neutralen pH-Werten eingesetzt wird (siehe Schema). Bei niedrigen pH-Werten ist die Reaktion weit weniger effizient und verläuft vermutlich nach einem anderen Mechanismus.

Asymmetric Transfer Hydrogenation of Ketones in 2‐Propanol Catalyzed by Arsinooxazoline—Ruthenium(II) Complex.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Highly Efficient Iridium Catalyst for Asymmetric Transfer Hydrogenation of Aromatic Ketones under Base-Free Conditions

[reaction: see text] Catalytic systems generated in situ from the chiral PNNP ligands with iridium or rhodium hydride complexes exhibited excellent catalytic activity and good enantioselectivity in the asymmetric transfer hydrogenation of aromatic ketones without added base. The best result was obtained in the IrH(CO)(PPh(3))(3)-ligand 2 catalytic system with up to 99% yield and 97% ee.