Mechanistic studies of amide bond scission during acidolytic deprotection of Pip containing peptide
Chiara Rubini1, Alessio Osler, Andrea Calderan
1Institute of Biomolecular Chemistry of CNR, Padua Unit, 35131 Padua, Italy.
Abstract:
Unusual TFA catalyzed cleavage reaction is reported for peptide containing pipecolic acid residues. Although the use of TFA under standard cleavage conditions is sufficiently mild to prevent degradation of the desired products, the amide bond between consecutive pipecolic acid residues is unexpectedly hydrolyzed by standard TFA treatment. The hydrolysis is proposed to proceed via an oxazolinium ion intermediate. This mechanism is supported by H/D exchange as observed by ESI-MS and NMR experiments.
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