Synlett 2004(10): 1826-1828  
DOI: 10.1055/s-2004-829553
LETTER
© Georg Thieme Verlag Stuttgart · New York

Ethyl Propiolate: A Simple and Convenient Peptide Coupling Reagent

Bogdan Iorga, Jean-Marc Campagne*
ICSN-CNRS, Avenue de la Terrasse, 91198 Gif sur Yvette, France
Fax: +33(1)69077247; e-Mail: campagne@icsn.cnrs-gif.fr;
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Publikationsverlauf

Received 26 May 2004
Publikationsdatum:
15. Juli 2004 (online)

Abstract

Ethyl propiolate has been used to activate N-protected amino acids to form a moderately activated vinyl-ester which aminolysis requires a catalytic amount of sodium bisulfite.

13

The mechanism is believed to imply the catalysis of the tertiary amine (Scheme [1] ) and not a direct Michael addition of the carboxylate since no reaction is observed in the presence of various inorganic bases.

14

One referee has suggested that lower yields could be explained by the formation of a Schiff base from by product 13 and the amino ester. However, this kind of by-product was never observed either by TLC or by 1H NMR on the crude mixture.