Optimization of Asymmetric Catalysts Using Achiral Ligands:  Metal Geometry-Induced Ligand Asymmetry†

2001 ◽  
Vol 3 (14) ◽  
pp. 2161-2164 ◽  
Author(s):  
Timothy J. Davis ◽  
Jaume Balsells ◽  
Patrick J. Carroll ◽  
Patrick J. Walsh
Keyword(s):  
Asymmetric Catalysts

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%.

Polymer-Supported BisBINOL Ligands for the Immobilization of Multicomponent Asymmetric Catalysts

2003 ◽  
Vol 5 (15) ◽  
pp. 2647-2650 ◽  
Author(s):  
Tetuya Sekiguti ◽  
Yoshimasa Iizuka ◽  
Shinobu Takizawa ◽  
Doss Jayaprakash ◽  
Takayoshi Arai ◽  
...  
Keyword(s):  
Asymmetric Catalysts ◽  
Polymer Supported

Recent progress in Lewis acid-Lewis base bifunctional asymmetric catalysis

2005 ◽  
Vol 77 (12) ◽  
pp. 2047-2052 ◽  
Author(s):  
Motomu Kanai ◽  
Nobuki Kato ◽  
Eiko Ichikawa ◽  
Masakatsu Shibasaki
Keyword(s):  
Asymmetric Catalysis ◽  
Lewis Acid ◽  
Recent Progress ◽  
Lewis Base ◽  
Pyridine Derivatives ◽  
Asymmetric Catalysts ◽  
Strecker Reaction

Two enantioselective cyanation reactions, the Strecker reaction of ketoimines and the Reissert reaction of pyridine derivatives, promoted by Lewis acid-Lewis base bifunctional asymmetric catalysts are described.

Self-Supported Asymmetric Catalysts

2009 ◽  
pp. 155-177
Author(s):  
Wenbin Lin ◽  
David J. Mihalcik
Keyword(s):  
Asymmetric Catalysts

scholarly journals Can we measure catalyst efficiency in asymmetric chemical reactions? A theoretical approach

2009 ◽  
Vol 5 ◽  
Author(s):  
Shaimaa El-Fayyoumy ◽  
Matthew H Todd ◽  
Christopher J Richards
Keyword(s):  
Chemical Reactions ◽  
Small Molecule ◽  
Enantiomeric Excess ◽  
Catalytic Efficiency ◽  
Catalytic Systems ◽  
Asymmetric Catalysts ◽  
Asymmetric Catalytic ◽  
Short Period ◽  
Asymmetric Catalyst ◽  
Catalyst Efficiency

Small molecule asymmetric catalysts are often described as being “good” or “bad” but to date there has been no way of comparing catalyst efficiency quantitatively. We define a simple formula, Asymmetric Catalyst Efficiency (ACE), that allows for such a comparison. We propose that a catalyst is more efficient if fewer atoms are utilised to give a product in a required enantiomeric excess. We illustrate this concept by analysing several well-known asymmetric catalytic chemical reactions carried out in academic laboratories, and compare small molecule catalysts with enzymes. We conclude that ACE is a useful descriptor for the comparison of diverse catalytic systems. It is also noteworthy that, despite the relatively short period of investigation into small molecule catalysts, they are competitive with enzymes with regards to this measure of catalytic efficiency.

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