Recoverable Dendritic Phase-Transfer Catalysts that Contain (+)-Cinchonine-Derived Ammonium Salts

Jordi Rull, José Juan Jara, Rosa M. Sebastián, Adelina Vallribera, Carmen Nájera, Jean Pierre Majoral, Anne Marie Caminade

Research output: Contribution to journalArticleResearchpeer-review

8 Citations (Scopus)

Abstract

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Four new phosphorus dendrimeric phase-transfer catalysts are prepared that contain 12 (+)-cinchoninium salts on the surface obtained by the quaternisation of the quinuclidinic N atom. The asymmetric alkylation of a glycinate Schiff base with benzyl bromide is used as a benchmark reaction, and the dendrimeric catalyst that contains an allyl group on the O-9 hydroxy group of the cinchonine units is the most active. The recovery and reuse of the catalyst are possible for five consecutive runs without loss of activity and with only a slight decrease in enantioselectivity. If other electrophiles are used, substituted benzyl bromides give better results than other activated alkyl bromides to afford the corresponding R amino acid derivatives. A comparison of these results with those reported previously for similar cinchoninium salts shows that dendrimers could be a better support than other polymers for this type of organocatalysis.
Original languageEnglish
Pages (from-to)2049-2056
JournalChemCatChem
Volume8
Issue number12
DOIs
Publication statusPublished - 21 Jun 2016

Keywords

  • alkylation
  • dendrimers
  • enantioselectivity
  • organocatalysis
  • phase-transfer catalysis

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