A supramolecular hydrogel as a reusable heterogeneous catalyst for the direct aldol reaction

Rodríguez‐Llansola, Francisco; Miravet, Juan F.; Escuder, Beatriu

doi:10.1039/b916250j

Cited by 172 publications

(134 citation statements)

References 26 publications

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“…While unsubstituted compound 125a (20 mol%) gave moderated results in the presence of TFA (10 mol%) in MeOH at 25 • C [171], supramolecular hydrogel 125b (20 mol%), in toluene at 5 • C, gave aldol 54c in good results [172]. Furthermore, this heterogeneous catalyst could be recovered by simple decantation and reused up to three times affording similar results.…”

Section: Aldehydes As Electrophilessupporting

confidence: 56%

Organocatalyzed Aldol Reactions

Guillena¹

2013

Modern Methods in Stereoselective Aldol Reactions

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The use of catalytic enantioselective methods to perform an aldol reaction provides a direct entry for the synthesis of chiral compounds and is probably the most attractive way to achieve this goal with high control of the chemo-, regio-, diastereo-, and enantioselectivity. The application of biochemical methods based on enzyme aldolases or antibodies, which are discussed in other chapters, avoid the use of preformed enolates or their equivalents for enhancing the global atom efficiency of the process [1] for which the narrow substrate scope is a major drawback. The discovery of methodologies to carry out the enantioselective direct aldol reaction [2] has eluded the production of stoichiometric by-products increasing the substrate scope. This task could be accomplished by using small molecules as catalysts, such as metal complexes (which are covered along this book) and organic molecules, also known as organocatalysts [3]. The growth of this last research area and the direct aldol reaction are closely linked [4], with the report on the use of (S)-proline as catalyst for the intermolecular aldol [5] definitely being the push for the development of the organocatalytic methods as a competitive methodology for the synthesis of chiral compounds.In a strict sense, an organocatalyzed reaction is a process in which all the involved reagents and catalysis are purely organic compounds of low-molecular weight, excluding boron-and silicon-containing derivatives. However, in some cases, the presence of a silyl group only plays a steric role and therefore can also be considered as an organocatalyzed process. Also, if the organocatalyst involved in a reaction is immobilized in a polymer, a dendrimer, or even an inorganic material that serves only as a support to facilitate its recovery [6], it could still be considered as an organocatalyst, although those types of derivatives have been scarcely used in the natural product synthesis and therefore will be excluded from this chapter. Therefore, a comprehensive overview of the direct aldol reaction [7], emphasizing the reactivity, scope, selectivity, and limitations of the methodology and giving several examples of their application to the synthesis of biologically active compounds, is discussed in this chapter.

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Section: Aldehydes As Electrophilessupporting

confidence: 56%

Organocatalyzed Aldol Reactions

Guillena¹

2013

Modern Methods in Stereoselective Aldol Reactions

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“…The combination of peptide assembly and inorganic nanoparticles enables another route to produce nanomaterials which may possess catalytic activity as they fulfill the requirements of order, presentation of chemical moieties plus multivalency [27,29,35,43,44]. Nanoparticles decorated with functional ligands are particularly interesting in the development of catalysts based on multivalency.…”

Section: Peptide Functionalised Nanoparticles In Catalysismentioning

confidence: 99%

Short Peptides in Minimalistic Biocatalyst Design

Duncan

Ulijn

2015

Biocatalysis

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As an example, let's look at a common class of biocatalysts, proteases, which possess the ability to hydrolyse amide (as well as ester) bonds. This amide hydrolysis reaction is extremely challenging with a half-life of 450 years [9,10]. Protease enzymes make use of a catalytic triad (Figure 1a Abstract: We review recent developments in the use of short peptides in the design of minimalistic biocatalysts focusing on ester hydrolysis. A number of designed peptide nanostructures are shown to have (modest) catalytic activity. Five features are discussed and illustrated by literature examples, including primary peptide sequence, nanosurfaces/scaffolds, binding pockets, multivalency and the presence of metal ions. Some of these are derived from natural enzymes, but others, such as multivalency of active sites on designed nanofibers, may give rise to new features not found in natural enzymes. Remarkably, it is shown that each of these design features give rise to similar rate enhancements in ester hydrolysis. Overall, there has been significant progress in the development of fundamental understanding of the factors that influence binding and activity in recent years, holding promise for increasingly rational design of peptide based biocatalysts.

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“…It is well known that gelators having ac entral three-carbons pacer self-assemble in ad ifferent way to bolaamphiphilic gelators having alonger spacer. [38] This particularself-assemblybehavior may causea dditional competition for the coordination of the copper when the gelators PhTzVal 3 and N 3 Val 3 N 3 are heatedt ogether with the coppers alt, causingad epletioni nt he catalytic performance of Cu I -PhTzVal 3 .I na ll the diffractograms, it is also important to highlight the appearance of ap eak around Chem.E ur.J.2016, 22,8676 -8684 www.chemeurj.org 4.5 , which,a ccording to previously reported xerogels, can be ascribed to the periodicity in the direction of the hydrogenbondinga rray,t hus suggesting as elf-assembly of the gelator molecules in av ertical direction (z-axis) both in the azides and in the final product. [39] XRD analysis performed on the hybrid multicomponent metallogel mixtures at 50 %c onversion (Figure 9C,G ,a nd K) revealed that the structural rearrangement of the system may lead to as lowdowno ft he reaction, achieving ak ind of plateau at this stage (Figure 8).…”

Section: Catalysismentioning

confidence: 99%

Triazolyl‐Based Molecular Gels as Ligands for Autocatalytic ‘Click’ Reactions

Araújo

Díaz‐Oltra

Escuder

2016

Chemistry A European J

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A supramolecular hydrogel as a reusable heterogeneous catalyst for the direct aldol reaction

Cited by 172 publications

References 26 publications

Organocatalyzed Aldol Reactions

Organocatalyzed Aldol Reactions

Short Peptides in Minimalistic Biocatalyst Design

Triazolyl‐Based Molecular Gels as Ligands for Autocatalytic ‘Click’ Reactions

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