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Kupplung von Peptiden mit C-terminalen alpha,alpha-disubstituierten alpha-Aminosäuren via Oxazol-5(4H)-one


Wipf, Peter; Heimgartner, Heinz (1986). Kupplung von Peptiden mit C-terminalen alpha,alpha-disubstituierten alpha-Aminosäuren via Oxazol-5(4H)-one. Helvetica Chimica Acta, 69(5):1153-1162.

Abstract

The formation of peptide bonds between dipeptides 4 containing a C-terminal alpha,alpha-disubstituted alpha-amino acid and ethyl p-aminobenzoate (5) using DCC as coupling reagent proceeds via 4,4-disubstituted oxazol-5(4H)-ones 7 as intermediates (Scheme 3). The reaction yielding tripeptides 6 (Table 2) is catalyzed efficiently by camphor-10-sulfonic acid (Table 1).The main problem of this coupling reaction is the epimerization of the nonterminal amino acid in 4 via a mechanism shown in Scheme 1. CSA catalysis at 0° suppresses completely this troublesome side reaction. For the coupling of 2-Val-Aib-OH (11) and Fmoc-Pro-Aib-OH (14) with H-Gly-OBut (12) and H-Ala-Aib-NMe2 (15), respectively, the best results have been obtained using DCC in the presence of ZnC12 (Table 3).

Abstract

The formation of peptide bonds between dipeptides 4 containing a C-terminal alpha,alpha-disubstituted alpha-amino acid and ethyl p-aminobenzoate (5) using DCC as coupling reagent proceeds via 4,4-disubstituted oxazol-5(4H)-ones 7 as intermediates (Scheme 3). The reaction yielding tripeptides 6 (Table 2) is catalyzed efficiently by camphor-10-sulfonic acid (Table 1).The main problem of this coupling reaction is the epimerization of the nonterminal amino acid in 4 via a mechanism shown in Scheme 1. CSA catalysis at 0° suppresses completely this troublesome side reaction. For the coupling of 2-Val-Aib-OH (11) and Fmoc-Pro-Aib-OH (14) with H-Gly-OBut (12) and H-Ala-Aib-NMe2 (15), respectively, the best results have been obtained using DCC in the presence of ZnC12 (Table 3).

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Additional indexing

Other titles:Peptide-Bond Formation with C-Terminal alpha,alpha-Disubstituted alpha-Amino Acids via Intermediate Oxazol-5(4H)-ones
Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:German
Date:1986
Deposited On:03 Jun 2014 07:06
Last Modified:05 Apr 2016 17:54
Publisher:Wiley-Blackwell
ISSN:0018-019X
Funders:Schweizerischer Nationalfonds zur Förderung der wissenschaftlichen Forschung, F. Hoffmann-La Roche & Co. AG, Basel
Publisher DOI:https://doi.org/10.1002/hlca.19860690524

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