β-Isocupreidinate‒CaAl-layered double hydroxide composites—heterogenized catalysts for asymmetric Michael addition

Gábor Varga, Viktória Kozma, Vanessza Judit Kolcsár, Ákos Kukovecz, Zoltán Kónya, Pál Sipos, István Pálinkó, György Szὅllὅsi

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Abstract

β-isocupreidinate (β-iCu) anions having well-known structure and catalytic activity in various asymmetric reactions, were incorporated into the interlayer gallery of hydrocalumite (CaAl-LDH) by the partial delamination-restacking method. Silylation of the outer surface of the LDH with trimethyl silane was also employed to avoid the adsorption of β-iCu on the outer surface and to block the basic sites there. The obtained materials were characterized by a range of instrumental methods (X-ray diffractometry, scanning electron microscopy, ATR-IR and grazing incidence IR spectroscopies). The catalytic activities of the composites were tested in the asymmetric Michael addition of β-nitrostyrene and ethyl 2-fluoroacetoacetate. The β-iCu-pillared LDHs proved to be active and recyclable catalysts with very good diastereoselectivities and acceptable and in 2-propanol very good enantioselectivities. The silylated composite retained its activity and diastereoselectivity even in the third repeated run, when heptane was the solvent.

Original languageEnglish
Article number110675
JournalMolecular Catalysis
DOIs
Publication statusAccepted/In press - Jan 1 2019

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Keywords

  • CaAl-layered double hydroxide
  • Catalysis of asymmetric Michael addition
  • Intercalation of β-isocupreidiniate
  • SEM, IR characterizations
  • XRD

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology
  • Physical and Theoretical Chemistry

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