Hydrogenation of 1-phenyl-1,2-propanedione over Pt catalysts modified by cinchona alkaloid O-ethers and the kinetic resolution of the 1-hydroxyketones generated

A1 Journal article (refereed)


Internal Authors/Editors


Publication Details

List of Authors: Busygin I, Warna J, Toukoniitty E, Murzin DY, Leino R
Publisher: ACADEMIC PRESS INC ELSEVIER SCIENCE
Publication year: 2008
Journal: Journal of Catalysis
Journal acronym: J CATAL
Volume number: 254
Issue number: 2
Start page: 339
End page: 348
Number of pages: 10
ISSN: 0021-9517


Abstract

Nine cinchona alkaloid O-ethers together with cinchonidine and cinchonine were studied as chiral modifiers in the enantioselective hydrogenation of 1-phenyl-1,2-propanedione over Pt/Al(2)O3. The influence of the O-substituent on the reaction rate, selectivity and product distribution was investigated. Apparent rate constants for all hydrogenation steps were calculated using a first-order kinetic approach resulting in a good agreement between the experimentally recorded and predicted concentrations. The experimentally observed structure-selectivity effects indicate that the mechanisms of enantiodifferentiation over the catalyst modified by parent cinchona alkaloids and their ether derivatives differ from each other. Moreover, the modifier structure-selectivity dependence and the solvent effect were different for enantio- and diastereoselection in the 1-phenyl-1,2-propanedione and 1-hydroxyketone hydrogenations. Correlation between the modifier substituent bulkiness and diastereoselectivity of the 1-hydroxyketone hydrogenation was observed. Data on the inversion of enantioselectivity of 1-phenyl-1,2-propanedione hydrogenation, diastereoselectivity and the sense of kinetic resolution of the 1-hydroxyketones were presented. Due to the complexity of the reaction network, several competing mechanistic pathways may be present in a single reaction system. (C) 2008 Elsevier Inc. All rights reserved.


Keywords

1-phenyl-1,2-propanedione, cinchona alkaloids, heterogeneous catalysis, hydrogenation kinetics, inversion of diastereoselectivity, inversion of enantioselectivity

Last updated on 2019-13-11 at 02:41