Synthetic enzymes—4

Colonna, Stefano; Molinari, Henríette; Banfi, Stefano; Juliá, S.; Masana, Jaume; Álvarez, Ángel L.

doi:10.1016/s0040-4020(01)88574-4

Cited by 140 publications

(39 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The better performances of the L-(-Me)Leu peptides as stereoselective catalysts is in agreement with the side-chain dependence observed with the homopeptides based on coded amino acids. 50 Furthermore, we observed a general increase of the ee with the lengthening of the peptide chain and, likely, of the stability of its three-dimensional (3D) structure. Even if this enhancement is not particularly high to allow us to draw general conclusions, it may be an hint that the helical content of the peptide plays a role in determining the stereoselection of the process.…”

Section: -Tetrasubstituted Amino Acid Based Peptidesmentioning

confidence: 79%

C^α‐Tetrasubstituted amino acid based peptides in asymmetric catalysis

et al. 2005

View full text Add to dashboard Cite

C(alpha)-tetrasubstituted alpha-amino acids constitute a powerful tool for controlling the conformation of short peptide sequences. Chiral peptides may be used in stereoselective reactions both for asymmetric induction and in kinetic resolution. By reviewing recent data from our own laboratories and by presenting new results on the stereoselective oxidation of chalcone to the corresponding oxide, this contribution shows that the control of peptide conformation is a critical issue in order to achieve successful stereoselective catalysis.

show abstract

Section: -Tetrasubstituted Amino Acid Based Peptidesmentioning

confidence: 79%

C^α‐Tetrasubstituted amino acid based peptides in asymmetric catalysis

et al. 2005

View full text Add to dashboard Cite

show abstract

“…Insufficient water in the solvent mixture inactivated the laccase, thus inhibiting the second peptide/ enzyme-catalysed oxidation step. Inspired by the Juliá-Colonna asymmetric epoxidation using polyamino acid catalysts, 175 poly-L-leucine was used as a recyclable organocatalyst in the second step of the sequential Claisen-Schmidt condensation, followed by an asymmetric epoxidation one-pot process, whereas the initial step was carried out using KOH aqueous solution. 176 The scope of the reaction was demonstrated using various benzaldehyde and acetophenone derivatives.…”

Section: One-pot Reactions Using Heterogenized Chiral Organocatalystsmentioning

confidence: 99%

“…214 These reactions, previously carried out using homogeneous hydrogenation catalysts, 215,216 were studied in more detail than the above presented one-pot reaction of ketoximes. In most of these studies, acetophenone 33a was transformed into (R)-1-phenylethylacetate (176) by hydrogenation using supported Pd catalysts to produce racemic 1-phenylethanol (175) followed by acylation with ethyl acetate, applying the immobilized CALB (Novozym-435) catalyst. 214,[217][218][219][220][221] In contrast to the one-pot reaction of ketoximes, in the transformation of 33a it was shown that the Pd catalyst was not efficient in the racemization step.…”

Section: View Article Onlinementioning

confidence: 99%

Asymmetric one-pot reactions using heterogeneous chemical catalysis: recent steps towards sustainable processes

Szőllősi

2018

Catal. Sci. Technol.

View full text Add to dashboard Cite

The preparation of optically pure fine chemicals is among the most important and challenging tasks met by organic chemists. Recently, significant efforts have been focused on the development of green and sustainable procedures for the synthesis of these high value-added compounds. Asymmetric heterogeneous catalysis has provided efficient solutions to these challenges. The application of heterogeneous chiral catalysts in one-pot processes combines the advantages of use of these materials with time, material, and energy savings associated with cascade or sequential procedures. This review surveys these asymmetric onepot reactions reported until July 2017, in which a heterogeneous chemical catalyst has been applied either as a single multifunctional catalyst or in combination with a second catalytically active material. These processes include one-pot procedures catalysed by carefully designed solids obtained by the immobilization of chiral metal complexes, by anchoring chiral organocatalysts, or by modifying catalytic surfaces with optically pure compounds, which may also incorporate uncatalyzed and homogeneously catalysed steps. Methods applying achiral heterogeneous catalysts in combination with soluble chiral chemical catalysts or biocatalysts are also presented. Sophisticated, finely tuned materials have been applied in most of these reactions, which have been discussed along with the main requirements necessary to perform these transformations in a one-pot manner.

show abstract

“…[3] One of the early demonstrations of chiral polymers in catalysis was the use of polypeptides as catalysts in the enantioselective nucleophilic epoxidation of chalcone with hydrogen peroxide, in what has become known as the Julia-Colonna epoxidation. [5][6][7][8] Using polyalanine as the catalyst, the epoxide product could be obtained in up to 96 % enantiomeric excess (ee), depending on the length of the polypeptide (Scheme 1). This was the first indication of a macromolecular amplification of chirality, although a helical structure has not been proven for these peptides.…”

Section: Static Helical Polymersmentioning

confidence: 99%