Pt-cinchonidine catalyzed asymmetric catalytic cascade reaction of 2-nitrophenylpyruvates in flow system

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5 Citations (Scopus)

Abstract

The asymmetric heterogeneous catalytic cascade reaction of ethyl 2-nitro-3-methylphenylpyruvate has been investigated over platinum modified by cinchonidine in continuous-flow system using a fixed-bed reactor. The high selectivities and enantioselectivities of the (R)-3-hydroxy-3,4-dihydro-8-methylquinolin-2(1H)-one obtained in previous studies in batch reactor were not reached. The catalyst was in situ prehydrogenated and premodified with cinchonidine, and the reaction conditions optimized for batch reactor were changed in order to increase the yield and enantioselectivity of the desired product under flow conditions. Results obtained in the flow apparatus contributed to the understanding of the reaction pathway through which the quinolone is formed. It was shown that, at low conversions, the intermediate aminohydroxyester desorbs preferentially and is further transformed by readsorption and cyclization to the quinolone derivative after complete disappearance of the 2-nitrophenylpyruvate. However, at high conversion, the formation of the quinolone may also occur instantaneously on the Pt surface following the two competitive reduction steps. The ratio of the product formed through these two pathways is determined by the reaction conditions and the system used.

Original languageEnglish
Pages (from-to)210-215
Number of pages6
JournalJournal of Flow Chemistry
Volume5
Issue number4
DOIs
Publication statusPublished - Dec 2015

Keywords

  • Asymmetric
  • Cascade reaction
  • Cinchona alkaloid
  • Hydroquinolone
  • Platinum

ASJC Scopus subject areas

  • Chemistry (miscellaneous)
  • Fluid Flow and Transfer Processes
  • Organic Chemistry

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