Calixarene-based chiral phase-transfer catalysts derived from cinchona alkaloids for enantioselective synthesis of α-amino acids

BOZKURT S., Durmaz M., Yilmaz M., Sirit A.

Tetrahedron Asymmetry, vol.19, no.5, pp.618-623, 2008 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 19 Issue: 5
  • Publication Date: 2008
  • Doi Number: 10.1016/j.tetasy.2008.02.006
  • Journal Name: Tetrahedron Asymmetry
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.618-623
  • Uşak University Affiliated: Yes

Abstract

The synthesis of the first calixarene-based chiral phase-transfer catalysts derived from cinchona alkaloids has been achieved in two steps from p-tert-butylcalix[4]arene. The catalytic efficiency of the chiral calix[4]arenes 3a-c was evaluated by carrying out the phase-transfer alkylation of N-(diphenylmethylene)glycine ethyl ester with benzyl bromide. Various factors that affect the chemical yield and enantioselectivity were also examined. Benzylation of glycine imine 4 using calix[4]arene-based dimeric catalyst 3a as a chiral phase-transfer catalyst in toluene/CHCl3 mixture (7:3 v/v) at 0 °C gave the best enantioselectivities and yields in the presence of aqueous NaOH. © 2008 Elsevier Ltd. All rights reserved.