Chiral organocatalysts based on lipopeptide micelles for aldol reactions in water

Research output: Contribution to journalArticleScientificpeer-review

Researchers

  • B. M. Soares
  • Maria Victoria Aguilar-Pontes
  • Emerson R. Silva
  • M. D. Coutinho-Neto
  • Ian W. Hamley
  • M. Reza
  • Janne Ruokolainen

  • Wendel A. Alves

Research units

  • Universidade Federal do ABC
  • Universidade Federal de Sao Paulo
  • University of Reading

Abstract

A comprehensive study of the self-assembly in water of a lipopeptide consisting of a sequence of L-proline, L-arginine and L-tryptophan with a hydrocarbon chain has been performed. Fluorescence assays were used to determine the critical aggregation concentration. In situ small-angle X-ray scattering (SAXS) and molecular dynamics simulations showed the presence of spherical micelles with diameters around 6 nm. In agreement with these results, cryo-TEM images showed globular aggregates with diameters ranging from approximate to 4 nm up to approximate to 9 nm. Furthermore, the lipopeptide catalytic activity has been tested for the direct aldol reaction between cyclohexanone and p-nitrobenzaldehyde, and we have observed that the self-association of the organocatalyst played a critical role in the enhanced activity. Water affects the selectivity, and poor results are obtained under neat reaction conditions. The location of the catalytic groups at the lipopetide/ water solvent interface also endowed unusual selectivity in the catalyzed aldol reactions. Under optimized reaction conditions, high yields (up to >99%), good enantioselectivity (ee up to 85%) and high diastereoselectivity (ds up to 92 : 8) were obtained.

Details

Original languageEnglish
Pages (from-to)1181-1189
Number of pages9
JournalPhysical Chemistry Chemical Physics
Volume19
Issue number2
Publication statusPublished - 2017
MoE publication typeA1 Journal article-refereed

    Research areas

  • MOLECULAR-DYNAMICS SIMULATIONS, OXYGENATED METHYL KETONES, SMALL-ANGLE SCATTERING, FORCE-FIELD, ASYMMETRIC ORGANOCATALYSIS, 1,5-ASYMMETRIC INDUCTION, POLYMER-SOLUTIONS, AQUEOUS-MEDIA, AMBER, FLUORESCENCE

ID: 13705641