Heterogeneous Asymmetric Hydrogenation Research Articles

Magnetically Recoverable Chiral Catalysts Immobilized on Magnetite Nanoparticles for Asymmetric Hydrogenation of Aromatic Ketones.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Efficient Heterogeneous Asymmetric Transfer Hydrogenation Catalyzed by Recyclable Silica‐Supported Ruthenium Complexes.

Easily accessible N-(p-tolylsulfonyl)-1,2-diphenylethylenediamine-(TsDPEN-)derived organic–inorganic hybrid ligands were prepared and applied to the heterogeneous asymmetric transfer hydrogenation in traditional HCO2H/NEt3 and in water with HCO2Na as the hydrogen source and sodium dodecyl sulfate (SDS) as the phase-transfer catalyst. The reactions demonstrated high catalytic activities and excellent enantioselectivities for most aromatic ketones and the imine tested, with results similar to those in homogeneous catalysis.In particular, this heterogeneous catalyst can be readily recovered and used in multiple consecutive catalytic runs with the high enantioselectivity maintained both in HCO2H/NEt3 and in water. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

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

AbstractFor Abstract see ChemInform Abstract in Full Text.

Programmed Assembly of Two Different Ligands with Metallic Ions: Generation of Self‐Supported Noyori‐Type Catalysts for Heterogeneous Asymmetric Hydrogenation of Ketones.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Magnetically Recoverable Chiral Catalysts Immobilized on Magnetite Nanoparticles for Asymmetric Hydrogenation of Aromatic Ketones

Novel heterogenized asymmetric catalysts were synthesized by immobilizing preformed Ru catalysts on magnetite nanoparticles via the phosphonate functionality and were characterized by a variety of techniques, including TEM, magnetization, and XRD. These nanoparticle-supported chiral catalysts were used for enantioselective heterogeneous asymmetric hydrogenation of aromatic ketones with very high enantiomeric excess values of up to 98.0%. The immobilized catalysts were easily recycled by magnetic decantation and reused for up to 14 times without loss of activity and enantioselectivity. Orthogonal nature of the present catalyst immobilization approach should allow the design of other superparamagnetic nanoparticle-supported asymmetric catalysts for a wide range of organic transformations.

Efficient Heterogeneous Asymmetric Transfer Hydrogenation Catalyzed by Recyclable Silica‐Supported Ruthenium Complexes

AbstractEasily accessible N‐(p‐tolylsulfonyl)‐1,2‐diphenylethylenediamine‐(TsDPEN‐)derived organic–inorganic hybrid ligands were prepared and applied to the heterogeneous asymmetric transfer hydrogenation in traditional HCO2H/NEt3 and in water with HCO2Na as the hydrogen source and sodium dodecyl sulfate (SDS) as the phase‐transfer catalyst. The reactions demonstrated high catalytic activities and excellent enantioselectivities for most aromatic ketones and the imine tested, with results similar to those in homogeneous catalysis.In particular, this heterogeneous catalyst can be readily recovered and used in multiple consecutive catalytic runs with the high enantioselectivity maintained both in HCO2H/NEt3 and in water. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Programmed Assembly of Two Different Ligands with Metallic Ions: Generation of Self-Supported Noyori-type Catalysts for Heterogeneous Asymmetric Hydrogenation of Ketones

Programmed assembly strategy has been first applied to the generation of self-supported Noyori-type catalysts for asymmetric hydrogenation of ketones by spontaneous heterocoordination of bridged diphosphine and diamine ligands with Ru(II) metallic ions. The immobilized catalyst demonstrates excellent enantioselectivity and activity in the heterogeneous catalysis of the hydrogenation of aromatic ketones and can be recovered and recycled at least seven times without obvious loss of selectivity and activity.

Highly Efficient and Recyclable Heterogeneous Asymmetric Transfer Hydrogenation of Ketones in Water.

A highly efficient heterogeneous asymmetric transfer hydrogenation of ketones in water was developed for the first time, which exhibited excellent enantioselectivities, distinct acceleration effect and remarkably high recyclabilities.

Preparation of polymer-supported Ru-TsDPEN catalysts and use for enantioselective synthesis of (S)-fluoxetine

Polymer-supported chiral ligands 9 and 17 were prepared based on Noyori's (1S,2S)- or (1R,2R)-N-(p-tolylsulfonyl)-1,2-diphenylethylenediamine. The combination with [RuCl2(p-cymene)]2 has been shown to exhibit high activities and enantioselectivities for heterogeneous asymmetric transfer hydrogenation of aromatic ketones (19a-c) with formic acid-triethylamine azeotrope as the hydrogen donor, whereby affording the respective optically active alcohols 20a-c, the key precursors of chiral fluoxetine. As exemplified by ligand 17 for substrate 19c, the catalysts can be recovered and reused in three consecutive runs with no significant decline in enantioselectivity. The procedure avoids the plausible contamination of fluoxetine by the toxic transition metal species.

Catalysis-based enantioselective total synthesis of the macrocyclic spermidine alkaloid isooncinotine

A concise and efficient total synthesis of the spermidine alkaloid (-)-isooncinotine (1) incorporating a 22-membered lactam ring is outlined. The approach is largely catalysis-based, involving a selective iron-catalyzed alkyl-aryl cross-coupling reaction of a difunctionalized pyridine substrate, a heterogeneous asymmetric hydrogenation step to set the chiral center of the target, and a highly integrated ring-closing metathesis/hydrogenation sequence to forge the saturated macrocyclic edifice in a single operation.

Efficient Heterogeneous Asymmetric Transfer Hydrogenation of Ketones Using Highly Recyclable and Accessible Silica‐Immobilized Ru‐TsDPEN Catalysts.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Chiral, Porous, Hybrid Solids for Highly Enantioselective Heterogeneous Asymmetric Hydrogenation of β‐Keto Esters.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Chiral, Porous, Hybrid Solids for Highly Enantioselective Heterogeneous Asymmetric Hydrogenation of β‐Keto Esters

In der Zuschrift “Chiral, Porous, Hybrid Solids for Highly Enantioselective Heterogeneous Asymmetric Hydrogenation of β-Keto Esters” von A. Hu, H. L. Ngo und W. Lin1 versäumten es die Autoren, auf eine thematisch verwandte Zuschrift (J. Am. Chem. Soc. 2003, 125, 11 490–11 491) zu verweisen. Dort wird die Hydrierung aromatischer Ketone mit einem anderen Heterogenkatalysator auf der Basis von [Ru(4,4'-binap)(diamin)Cl2] beschrieben (mit bis zu 99.2 % ee), die einem abweichenden Mechanismus folgt. Die Autoren bitten um Entschuldigung für dieses Versehen.

Chiral, Porous, Hybrid Solids for Highly Enantioselective Heterogeneous Asymmetric Hydrogenation of β‐Keto Esters

Chiral, Porous, Hybrid Solids for Highly Enantioselective Heterogeneous Asymmetric Hydrogenation of β‐Keto Esters

Chiral Porous Hybrid Solids for Practical Heterogeneous Asymmetric Hydrogenation of Aromatic Ketones.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Highly efficient and recyclable heterogeneous asymmetric transfer hydrogenation of ketones in water.

A highly efficient heterogeneous asymmetric transfer hydrogenation of ketones in water was developed for the first time, which exhibited excellent enantioselectivities, distinct acceleration effect and remarkably high recyclabilities.

Efficient heterogeneous asymmetric transfer hydrogenation of ketones using highly recyclable and accessible silica-immobilized Ru-TsDPEN catalysts.

[reaction: see text] Chiral Ru-TsDPEN [N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine]-derived catalysts were first successfully immobilized onto amorphous silica gel and mesoporous silicas of MCM-41 and SBA-15 by an easily accessible approach. The catalyst immobilized on silica gel demonstrated remarkably high catalytic activities and excellent enantioselectivities (up to >99% ee) for the heterogeneous asymmetric transfer hydrogenation of various ketones. Particularly, the catalyst could be readily recovered and reused in multiple consecutive catalytic runs (up to 10 uses) with the completely maintained enantioselectivity.

Chiral, Porous, Hybrid Solids for Highly Enantioselective Heterogeneous Asymmetric Hydrogenation of β‐Keto Esters

Chiral, Porous, Hybrid Solids for Highly Enantioselective Heterogeneous Asymmetric Hydrogenation of β‐Keto Esters

Chiral, porous, hybrid solids for highly enantioselective heterogeneous asymmetric hydrogenation of beta-keto esters.

Chiral, porous, hybrid solids for highly enantioselective heterogeneous asymmetric hydrogenation of beta-keto esters.

Chiral porous hybrid solids for practical heterogeneous asymmetric hydrogenation of aromatic ketones.

Chiral porous zirconium phosphonates containing Ru-BINAP-DPEN moieties were synthesized via a molecular building-block approach, and characterized by a variety of techniques including TGA, adsorption isotherms, XRD, SEM, IR, and microanalysis. These hybrid solids were used for enantioselective heterogeneous asymmetric hydrogenation of aromatic ketones with remarkably high ee values of up to 99.2%. These solid catalysts can also be easily recycled and reused for eight times without the loss of activity and enantioselectivity. Ready tunability of such a molecular building-block approach will allow the optimization of these hybrid materials and promise to lead to other practically useful heterogeneous asymmetric catalysts.