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Title

Conformational rigidity: a necessary prerequisite of chiral modifiers used in heterogeneous enantioselective catalysis?

Authors
Orglmeister, Elisabeth
Mallat, Tamas
Baiker, Alfons
Published in Journal of Catalysis. 2005, vol. 232, no. 1, p. 137-142
Abstract In the hydrogenation of ketopantolactone, the (R,R) and (R,S) diastereomers of a new chiral modifier, pantoyl-naphthylethylamine, afforded 74 and 40% ee, respectively, to (R)-pantolactone. On the basis of NOE studies and theoretical calculations, the different properties of the diastereomers and in particular the effect of acid on the modifier structure are deduced from differences in conformational rigidity and steric constraint. In case of the (R,R)-diastereomer, a loose, extended structure in apolar solvent changes to a compact conformation via an additional intramolecular hydrogen bond, resulting in a more defined "chiral pocket" available for the reactant on the Pt surface.
Keywords Acid effectAsymmetric heterogeneous catalysisPt/Al2O3KetopantolactoneHydrogenationAb initio calculationNOEModifier conformation
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Deposited on : 2011-03-18

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