Phase-transfer-catalyzed asymmetric glycolate alkylation

Org Lett. 2004 Jun 24;6(13):2289-92. doi: 10.1021/ol0491235.

Abstract

[reaction: see text] Asymmetric surrogate glycolate alkylation has been performed under phase-transfer conditions. Diphenylmethyloxy-2,5-dimethoxyacetophenone with trifluorobenzyl cinchonidinium catalyst and cesium hydroxide provided alkylation products at -35 degrees C in high yield (80-99%) and with excellent enantioselectivities (90:10 to 95:5). Useful alpha-hydroxy products were obtained using bis-TMS peroxide Baeyer-Villiger conditions and selective transesterification. The intermediate aryl ester can be obtained with >99% ee after a single recrystallization. A tight ion-pair model for the observed (S)-stereoinduction is proposed.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetophenones*
  • Alkylation
  • Benzyl Compounds
  • Catalysis
  • Cinchona Alkaloids*
  • Glycolates / chemical synthesis
  • Glycolates / chemistry*
  • Stereoisomerism

Substances

  • Acetophenones
  • Benzyl Compounds
  • Cinchona Alkaloids
  • Glycolates
  • cinchonidine