Epimerization‐Free C‐Terminal Peptide Activation

Popovic, Stanimir; Bieräugel, Hans; Detz, Remko J.; Kluwer, Alexander M.; Koole, Jelmer A. A.; Streefkerk, Dieuwertje E.; Hiemstra, Henk; Maarseveen, Jan H. van

doi:10.1002/chem.201303347

Cited by 24 publications

(24 citation statements)

References 33 publications

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“…In earlier work we and others have shown that carboxylic acids can be conveniently transformed into aryl esters using the CLE reaction from aryl boronic acids or boroxines . Starting from arylboroxines, the CLE reaction even allows C‐terminal activation of peptides as aryl esters that were used in subsequent amidation reactions without loss of stereointegrity . In this letter we report the efficient synthesis of a wide variety of enol esters from commercially available alkenylboronic acids and boroxine pyridine complexes and some useful follow up transformations such as aminolysis, trans(thio)esterification, reduction, aminal and cyanohydrin ester formation.…”

Section: Methodsmentioning

confidence: 99%

Regio‐ and Stereoselective Chan‐Lam‐Evans Enol Esterification of Carboxylic Acids with Alkenylboroxines

2018

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Efficient and scalable Cu(II)-mediated enol esterification methodology of carboxylic acids from alkenyl boroxines and boronic acids is presented. The reaction shows a wide scope in aliphatic and aromatic carboxylic acids in combination with several alkenyl boroxines. In the case of 2-substituted alkenyl boroxines the double bond configuration was fully retained in the enol ester product. Also N-hydroxyimides and imides could be transformed in the respective amidooxy vinyl enol ethers and vinyl enamides. Finally, with the exception of methionine, all other 19 canonical amino acids showed their compatibility to give the enol esters in a stereoselective fashion.

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Section: Methodsmentioning

confidence: 99%

Regio‐ and Stereoselective Chan‐Lam‐Evans Enol Esterification of Carboxylic Acids with Alkenylboroxines

2018

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“…33 For example, Crich and Banerjee applied this strategy with a β-thiolfunctionalized phenylalanine for the synthesis of decapeptides.33a Recently, our group reported an epimerization-free synthesis of activated aryl ester of small peptides (e.g. 4-(methylsulfonyl)phenyl esters) via the Chan-Lam coupling 34. These esters were successfully applied in native chemical ligation thus avoiding the addition of thiophenol to the reaction mixture for the in situ generation of a thiol ester as in the more common procedure.…”

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confidence: 99%

Cinchona Alkaloid Catalyzed Sulfa-Michael Addition Reactions Leading to Enantiopure β-Functionalized Cysteines

et al. 2015

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Sulfa-Michael additions to α,β-unsaturated N-acylated oxazolidin-2-ones and related α,β-unsaturated α-amino acid derivatives have been enantioselectively catalyzed by Cinchona alkaloids functionalized with a hydrogen bond donating group at the C6' position. The series of Cinchona alkaloids includes known C6' (thio)urea and sulfonamide derivatives and several novel species with a benzimidazole, squaramide or a benzamide group at the C6' position. The sulfonamides were especially suited as bifunctional organocatalysts as they gave the products in very good diastereoselectivity and high enantioselectivity. In particular, the C6' sulfonamides catalyzed the reaction with the α,β-unsaturated α-amino acid derivatives to afford the products in a diastereomeric ratio as good as 93:7, with the major isomer being formed in an ee of up to 99%. The products of the organocatalytic sulfa-Michael addition to α,β-unsaturated α-amino acid derivatives were subsequently converted in high yields to enantiopure β-functionalized cysteines suitable for native chemical ligation.

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“…We thus conclude that the compound PC-d/l-Pgl-Me is a mixture of d-and l-enantiomer in ratio of 2.1:1 in favour for d-enantiomer. The epimerization of Pgl is known to occur very easily using standard coupling conditions and thus stereoselective synthesis would require specific reagents not employed in this work[44]. Chiral HPLC analysis was performed for enantiomeric mixture PC-d/l-Pgl-Me, racemic mixtures (PC-dl-Ala-Me, PC-dl-Leu-Et, PC-dl-Phe-Et, PC-dl-Val-Et) and for the samples of which we had the complete couple of antipodes.…”

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N-Pyrazinoyl Substituted Amino Acids as Potential Antimycobacterial Agents—the Synthesis and Biological Evaluation of Enantiomers

et al. 2020

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Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis (Mtb), each year causing millions of deaths. In this article, we present the synthesis and biological evaluations of new potential antimycobacterial compounds containing a fragment of the first-line antitubercular drug pyrazinamide (PZA), coupled with methyl or ethyl esters of selected amino acids. The antimicrobial activity was evaluated on a variety of (myco)bacterial strains, including Mtb H37Ra, M. smegmatis, M. aurum, Staphylococcus aureus, Pseudomonas aeruginosa, and fungal strains, including Candida albicans and Aspergillus flavus. Emphasis was placed on the comparison of enantiomer activities. None of the synthesized compounds showed any significant activity against fungal strains, and their antibacterial activities were also low, the best minimum inhibitory concentration (MIC) value was 31.25 µM. However, several compounds presented high activity against Mtb. Overall, higher activity was seen in derivatives containing l-amino acids. Similarly, the activity seems tied to the more lipophilic compounds. The most active derivative contained phenylglycine moiety (PC-d/l-Pgl-Me, MIC < 1.95 µg/mL). All active compounds possessed low cytotoxicity and good selectivity towards Mtb. To the best of our knowledge, this is the first study comparing the activities of the d- and l-amino acid derivatives of pyrazinamide as potential antimycobacterial compounds.

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Epimerization‐Free C‐Terminal Peptide Activation

Cited by 24 publications

References 33 publications

Regio‐ and Stereoselective Chan‐Lam‐Evans Enol Esterification of Carboxylic Acids with Alkenylboroxines

Regio‐ and Stereoselective Chan‐Lam‐Evans Enol Esterification of Carboxylic Acids with Alkenylboroxines

Cinchona Alkaloid Catalyzed Sulfa-Michael Addition Reactions Leading to Enantiopure β-Functionalized Cysteines

N-Pyrazinoyl Substituted Amino Acids as Potential Antimycobacterial Agents—the Synthesis and Biological Evaluation of Enantiomers

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