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Modifier–substrate interactions of various types in the Orito reaction: Reversal of the enantioselection in the hydrogenation of ketopantolactone on Pt modified by β-isocinchonine and O-phenylcinchonidine

Paper ID Volume ID Publish Year Pages File Format Full-Text
50346 46790 2013 5 PDF Available
Title
Modifier–substrate interactions of various types in the Orito reaction: Reversal of the enantioselection in the hydrogenation of ketopantolactone on Pt modified by β-isocinchonine and O-phenylcinchonidine
Abstract

The enantioselective hydrogenation of ketopantolactone (KPL) on Pt–alumina catalyst modified by β-isocinchonine (β-ICN) and O-phenylcinchonidine (PhOCD) in toluene, acetic acid and their mixtures under otherwise identical experimental conditions was studied. Reversal of the enantioselection was obtained dependent on the concentration of acetic acid (eemax = 17% (S) on Pt–PhOCD and 50% (R) on Pt–β-ICN, respectively). The possible role in enantioselection of adducts forming in the reaction mixture and the stability of PhOCD under the conditions of the hydrogenation was investigated by ESI-MS. The results of the nonlinear phenomenon measurements on β-ICN + PhOCD mixtures suggest that the intermediate surface complexes β-ICN–KPL and PhOCD–KPL responsible for the opposite enantioselection include different types of interactions and the enantioselection is directed by the competition between these interactions.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Hydrogenation of KPL over Pt modified β-ICN and PhOCD was studied. ► The reversal of the enantioselection was dependent on the AcOH concentration. ► PhOCD did not suffered C–O bond hydrogenolysis in the presence of AcOH. ► Competing intermediate complexes involving different interactions were suggested.

Keywords
Enantioselective hydrogenation; Platinum; Cinchona alkaloid; Ketopantolactone; Reversal of enantioselectivity; Intermediate complexes
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Modifier–substrate interactions of various types in the Orito reaction: Reversal of the enantioselection in the hydrogenation of ketopantolactone on Pt modified by β-isocinchonine and O-phenylcinchonidine
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Communications - Volume 32, 5 February 2013, Pages 81–85
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us