Ethyl Propiolate: A Simple and Convenient Peptide Coupling Reagent

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.

Key words

peptide - coupling reagent - sodium bisulfite

References

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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.