Amide group participation in the acid-catalyzed cleavage of peptide bond

Studies on the use of N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline for the synthesis of acylamino acid anilides and p-nitroanilides

“…Cleavage probably occurs through formation of the sxazolone. Similar acidolytic cleavage of the peptide bonds at the terminal residues of acylated peptide chains has been reported to occur in hot trifluoroacetic acid (29) or methanolic hydrogen chloride (30). Neither an acetylamino acid anilide nor a benzoylated dipeptide was cleaved under the conditions used (Table 3).…”

Intramolecular reaction of specific substrate as a step in α‐chymotrypsin catalyzed hydrolysis

“…It has been shown that Na-acylated amino acids are readily converted to the corresponding oxazolinones when their carboxylic function is activated by a suitable electron-withdrawing substituent [15]. Oxazolinones (III) can also be obtained from _Na-acylated amino acid amides (I) through an intramolecular nucleophilic displacement catalyzed by an anhydrous acid solvent [16] In this case the electrophilicity of the ultimate carbonyl carbon is enhanced by the solvent protonation. It is noteworthy that in anhydrous acidic medium an A macyl amino acid amide (I) easily reacts with serine through the oxazolinone (III) intermediate [8] to yield an Na-acyl amino acyl-O-serine (V) which can be considered as a chemical equivalent of the acylenzyme:…”