Unexpected Chain-Terminating Side Reaction Caused by Histidine and Acetic Anhydride in Solid-Phase Peptide Synthesis

Abstract

Capping is a useful technique to facilitate purification of a crude deprotected peptide in solid-phase peptide synthesis. However, we observed a serious side reaction caused by the Ac₂O capping procedure, when it was applied to a synthesis of a peptide containing His. The mechanism of the side reaction was studied.