Asymmetric ketones

The use of chiral ruthenium catalysts can hydrogenate ketones asymmetrically in water. The introduction of surfactants into a water-soluble Ru(II)-catalyzed asymmetric transfer hydrogenation of ketones led to an increase of the catalytic activity and reusability compared to the catalytic systems without surfactants.8 Water-soluble chiral ruthenium complexes with a (i-cyclodextrin unit can catalyze the reduction of aliphatic ketones with high enantiomeric excess and in good-to-excellent yields in the presence of sodium formate (Eq. 8.3).9 The high level of enantioselectivity observed was attributed to the preorganization of the substrates in the hydrophobic cavity of (t-cyclodextrin. 

Keywords Aldol, Direct, Ketone, Asymmetric catalysis, Enantioselective reaction, Diastereo-selectivity, 1,2-Diol, Aldehyde, Enamine, Lewis acid, Bronsted base, Organocatalysis, Bimetal-... 

I.4.I.2. Amino, Hydroxy, and Phenylthio Ketones Asymmetric hydrogenation of amino ketones, in either a neutral or hydrochloride form, has extensively been studied. Both Rh(I) and Ru(II) complexes with an appropriate chiral diphosphine give a high enantioselectivity. As described in Scheme 1.42, a-aminoacetophenone hydrochloride is hydrogenated using a cationic Rh complex with (R)-MOC-BIMOP, an unsymmetricaJ biaryl diphosphine, to give the... 

Alkoxy)diborons, alkyne additions, 10, 727-728 Alkoxy-hydro carbonylation, in ionic liquids, 1, 863 Alkoxy ketones, asymmetric hydrogenation, 10, 47 Alkoxylation... 

Hydroxyl ketones, asymmetric hydrogenation, 10, 47 Hydroxyl-substituted cyclopropanes, solvomercuration,... 

Phenylthio ketones, asymmetric hydrogenation, 10, 47 Phenylthiourea, with trinuclear Os clusters, 6, 747 Phenyltris(A r/-butylthio)methylborato ligands, in cobalt(II) complexes, 7, 18... 

Sharpless asymmetric epoxidation of allylic alcohols, asymmetric epoxidation of conjugated ketones, asymmetric sulfoxidations catalyzed, or mediated, by chiral titanium complexes, and allylic oxidations are the main classes of oxidation where asymmetric amplification effects have been discovered. The various references are listed in Table 4 with the maximum amplification index observed. 

It has long been possible to hydrogenate a wide range of functionalized ketones asymmetrically achieving selectivities of over 90 % ee. Thus, pharmaceutically important 1,2-amino alcohol derivatives have been available since 1979 with... 

Silanes (H2SiPh2) also reduce" ketones asymmetrically in the presence of the chiral catalyst 6.65. 

New stereogenic centres from prochiral units in planar molecules Enantiotopic and diastereotopic groups Asymmetric Reduction of Unsymmetrical Ketones Asymmetric boron or aluminium hydrides Asymmetric reduction by boranes Reduction of ketones with Ipc2BCl (DIP-Chloride ) Asymmetric Electrophiles... 

Reactions of chiral allylic boranes with carbonyl compounds Reactions of chiral allyl boranes with imines Asymmetric Addition of Carbon Nucleophiles to Ketones Addition of alkyl lithiums to ketones Asymmetric epoxidation with chiral sulfur ylids Asymmetric Nucleophilic Attack by Chiral Alcohols Deracemisation of arylpropionic acids Deracemisation of a-halo acids Asymmetric Conjugate Addition of Nitrogen Nucleophiles An asymmetric synthesis of thienamycin Asymmetric Protonation... 

With prochiral ketones asymmetric induction at both silicon and carbon centers takes... 

With chiral ketones, asymmetric induction takes place at a silicon center even with an achiral catalyst such as Rh(PPh3)3Cl, which is an application of the stereoselective hydrosiiyiation of cyclic terpene ketones (see 14.4.4.2). Double asymmetric induction is also effective and achieves a high optical yield ... 

The CBS (Corey-Bakshi-Shibata) reagent is a chiral catalyst derived from proline. Also known as Corey s oxazaborolidine, it is used in enantioselective bo-rane reduction of ketones, asymmetric Diels-Alder reactions and [3 + 2] cycloadditions. 

Keywords Ketones Asymmetric transfer hydrogenation Chiral metal catalysts Recyclable catalysts Transfer hydrogenation in water... 

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