Search results for "aldol"

New ionic liquid-modified silica gels as recyclable materials for L-proline- or H-Pro-Pro-Asp-NH2-catalyzed aldol reaction

2007

l-proline and the tripeptide H-Pro-Pro-Asp-NH2 (1) have been supported, by adsorption, onto the surface of modified silica gels functionalized with a monolayer of covalently attached 1,2-dimethyl-imidazolium chloride, tetrafluoroborate or hexafluorophosphate ionic moieties, respectively. Three different linkers were used to attach the ionic liquid moiety to the surface of these supports. The resulting materials have been used as catalysts for the aldol reaction between acetone and several substituted benzaldehydes. Good yields and enantioselectivities, comparable to or better than those obtained under homogeneous conditions, were obtained. These materials are easily recovered by filtration,…

Polystyrene-supported proline and prolinamide. Versatile heterogeneous organocatalysts both for asymmetric aldol reaction in water and α-selenenylati…

2007

A simple and efficient synthesis of polystyrene-supported proline and prolinamide has been carried out. Polystyrene-supported proline has been used as organocatalyst in the asymmetric aldol reaction between cyclohexanone and substituted benzaldehydes in water without any additive. High yields, diastereoselectivities and ee values have been observed. The versatility of this resin was demonstrated in the α-selenenylation of aldehydes. Both proline and prolinamide resins gave high yields. Recycling studies showed that the proline resin gave better results than prolinamide resin.

Identification of proteins in excretory/secretory extracts of Echinostoma friedi (Trematoda) from chronic and acute infections.

2006

In the present study, we describe the investigation of Echinostoma friedi excretory/secretory products using a proteomic approach combined with the use of heterologous antibodies. We have identified 18 protein spots corresponding to ten proteins, including cytoskeletal proteins like actin, tropomyosin, and paramyosin; glycolytic enzymes like enolase, glyceraldehyde 3P dehydrogenase, and aldolase; detoxifying enzymes like GSTs; and stress proteins like heat shock protein (Hsp) 70. Among these proteins, both actin and, to a lesser extent, Hsp70, exhibited differential expression patterns between chronic and acute infections in the Echinostoma-rodent model, suggesting that these proteins may p…

Proton-Induced Multiple Changes of the Absorption and Fluorescence Spectra of Amino-Aza-Oligo(Phenylenevinylene)s

2008

Fluorescent dyes with a high sensitivity of their optical spectra towards changes of the environment were prepared via aldol condensation or Horner olefinations. The main chromophore is a quadrupolar N-substituted 1,4-distyrylbenzene which allows protonation and complexation at various positions resulting in a series of different and significant changes of the optical spectra. The sensitivity of the absorption and emission spectra on solvent polarity, acid, and cations is reported.

Changes in enzymes involved in photosynthesis and other metabolic processes in the fruit of Opuntia ficus-indica during growth and ripening

2011

The aim of this study was to investigate changes in the abundance of a number of enzymes in the peel, core and seeds of fruits of Opuntia ficus-indica (L.) Miller during development. The enzymes studied were phosphoenolpyruvate carboxylase (PEPC; EC: 4.1.1.31), ribulose-1,5-bisphosphate carboxylase/oxygenase (RUBISCO; EC: 4.1.1.39), aldolase (EC: 4.1.2.13), pyruvate, orthophosphate dikinase (PPDK; EC: 2.7.9.1), phosphoenolpyruvate carboxykinase (PEPCK; EC: 4.1.1.49) and aspartate aminotransferase (AspAT; EC: 2.6.1.1). To detect these enzymes, antibodies specific for each enzyme were used to probe Western blots of sodium dodecyl sulphate polyacrylamide gels. Fruit weight increased throughout…

Diastereoselective Synthesis of Spiro[pyrazolone-4,3′-tetrahydrothiophenes] via a Sulfa-Michael/Aldol Domino Reaction

2016

Synthesis : journal of synthetic organic chemistry 48(23), 4091-4098(2016). doi:10.1055/s-0035-1562473

L-prolinammide supportata su polistirene come organocatalizzatore altamente enantioselettivo nella reazione aldolica diretta

2007

Gaspar Veronensis n. ca. 1400 - m. 1474

2012

Petrus Candidus v. 1481 - m. 1513

2012

Supported ionic liquids. New recyclable materials for the L-proline-catalyzed aldol reaction

2006

New materials for L-proline recycling have been developed. These materials have been applied to the L-proline-catalyzed aldol reaction between acetone and several aldehydes. The L-proline has been supported on the surface of modified silica gels with a monolayer of covalently attached ionic liquid with or without additional adsorbed ionic liquid. Good yields and ee values, comparable with those obtained under homogeneous conditions, have been obtained especially with imidazolinium-modified and 4-methylpyridinium-modified silica gels. Moreover, these materials have been easily recovered by simple filtration and studies about their reuse have been carried out. These studies showed that these …