An unusual electronic effect of an aromatic-F in phase-transfer catalysts derived from cinchona-alkaloid

Org Lett. 2002 Nov 28;4(24):4245-8. doi: 10.1021/ol0267679.

Abstract

[structure: see text] Various N-benzylcinchonidinium salts were prepared to study electronic factors in the catalytic enantioselective phase-transfer alkylation of glycine anion equivalent. An ortho-fluoro substituent on the benzyl group in the quaternary ammonium salt dramatically increased the enantioselectivity in the alkylation. O(9)-Allyl-N-2',3',4'-trifluorobenzylhydrocinchonidinium bromide (27), which gave the highest enantioselectivity of the catalysts studied, was used to prepare 12 alpha-alkylated amino acid derivatives in 94 approximately >99% ee.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkylation
  • Amino Acids / chemical synthesis*
  • Amino Acids / chemistry*
  • Bromides / chemistry*
  • Catalysis
  • Cinchona Alkaloids / chemistry*
  • Electrochemistry
  • Electrons
  • Glycine / chemistry*
  • Molecular Conformation
  • Molecular Structure
  • Stereoisomerism

Substances

  • Amino Acids
  • Bromides
  • Cinchona Alkaloids
  • Glycine