Quantitative expression of dynamic kinetic resolution of chirally labile enantiomers: stereoselective hydrogenation of 2-substituted 3-oxo carboxylic esters catalyzed by BINAP-ruthenium(II) complexes

Hydrogenation of chirally unstable 2-substituted 3-oxo carboxylic esters gives a mixture of four stereoisomeric hydroxy esters. Use of BINAP-Ru(II) complex catalysts allows selective production of one stereoisomer among four possible isomers. The stereoselectivity obtained by the dynamic kinetic res...

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Bibliographic Details
Published in:Journal of the American Chemical Society 1993-01, Vol.115 (1), p.144-152
Main Authors: Kitamura, M, Tokunaga, M, Noyori, R
Format: Article
Language:English
Subjects:
400201 - Chemical & Physicochemical Properties
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
Chemical reactivity
Chemistry
CHIRALITY
COMPLEXES
ESTERS
Exact sciences and technology
HYDROGENATION
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
ISOMERS
KINETICS
MATHEMATICAL MODELS
Organic chemistry
ORGANIC COMPOUNDS
PARTICLE PROPERTIES
RACEMIZATION
REACTION KINETICS
Reactivity and mechanisms
RUTHENIUM COMPLEXES
STEREOCHEMISTRY
SUBSTRATES
TRANSITION ELEMENT COMPLEXES
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Summary:Hydrogenation of chirally unstable 2-substituted 3-oxo carboxylic esters gives a mixture of four stereoisomeric hydroxy esters. Use of BINAP-Ru(II) complex catalysts allows selective production of one stereoisomer among four possible isomers. The stereoselectivity obtained by the dynamic kinetic resolution depends on facile in situ racemization of the substrates, efficient chirality recognition ability of the catalysts, and the structures of the ketonic substrate. The factors controlling the efficiency of the stereoselective hydrogenation are experimentally determined by reaction of racemic oxo esters using enantiomerically pure and racemic BINAP complexes. Quantitative expression of the dynamic kinetic resolution has been made by defining the product partition coefficients (w, x, y, and z), the relative reactivities of the enantiomeric substrates (k[sub fast]/k[sub slow]), and the relative ease with which stereoinversion and hydrogenation take place (k[sub inv]/k[sub fast]). The validity of the equations has been demonstrated by the graphical exhibition of the enantioselectivity and diastereoselectivity as a function of conversion of the substrates. 18 refs., 4 figs., 3 tabs.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja00054a020