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.
Original language | English |
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Pages (from-to) | 1181-1189 |
Number of pages | 9 |
Journal | Physical Chemistry Chemical Physics |
Volume | 19 |
Issue number | 2 |
DOIs | |
Publication status | Published - 2017 |
MoE publication type | A1 Journal article-refereed |
Keywords
- MOLECULAR-DYNAMICS SIMULATIONS
- OXYGENATED METHYL KETONES
- SMALL-ANGLE SCATTERING
- FORCE-FIELD
- ASYMMETRIC ORGANOCATALYSIS
- 1,5-ASYMMETRIC INDUCTION
- POLYMER-SOLUTIONS
- AQUEOUS-MEDIA
- AMBER
- FLUORESCENCE