Chiral organocatalysts based on lipopeptide micelles for aldol reactions in water

Autor(es)

Soares, B. M. ; Aguilar, A. M. ; Silva, E. R. ; Coutinho-Neto, M. D. ; Hamley, I. W. ; Reza, M. ; Ruokolainen, J. ; Alves, W. A.

• Tipo de documento: Artigo Científico
• Fonte: Physical Chemistry Chemical Physics; v. 19, n. 2, p. 1181-1189, 2017.
• Citações Web of Science: 7

Resumo

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. (AU)

• Processo FAPESP: 15/24018-1 - Conjugados polímero-peptídeo para formulação de hidrogéis e seu uso em detecção
• Beneficiário: Wendel Andrade Alves
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 08/57805-2 - Instituto de Bioanalítica
• Beneficiário: Lauro Tatsuo Kubota
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 13/12674-6 - Investigações estruturais em sistemas-modelo à base de peptídeos anfifílicos
• Beneficiário: Emerson Rodrigo da Silva
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado