5(4H)-Oxazolones as Intermediates in the Carbodiimide-and Cyanamide-Promoted Peptide Activations in Aqueous Solution

摘要

The formation of biopolymers in prebiotic environments is still unresolved regarding nucleic acids and functional peptides. Peptide function especially requires proper folding and hence sufficient lengths. In 1969, Cavadore and Previero observed that the EDC-mediated (EDC = 1-ethyl, 3-(3-dime-thylaminopropyl)carbodiimide hydrochloride) a-amino acid polymerization in water is significantly improved when N-acylated amino acids are introduced as initiators. Obviously, EDC is highly unlikely to have been abiotically formed but there are indications in the literature that underivatized carbodiimide HN=C=NH is involved as an intermediate in reactions of cyanamide, a prebiotically plausible reagent, and dicyandiamide is reported to behave similarly as carbo-diimides.