The cationized 9-fluorenylmethoxycarbonyl (Fmoc) protected amino acids were analyzed by the electros-pray ionization tandem mass spectrometry (ESI-MS/MS). A rearrangement reaction leading to the C-terminal hydroxyl group transfer was observed. The sodium adducts of Fmoc-OH was formed. A possible rearrangement mechanism was proposed. The rearrangement reaction depended on the Fmoc group, metal ions and metal ion radius. It was shown that the Fmoc group has a strong affinity to the hydroxyl group in the gas phase.
DU Jintang, LI Yanmei, ZHU Zhentai, CHEN Yi & ZHAO Yufen Laboratory of Bioorganic Phosphorus Chemistry, Department of Chem-istry, Tsinghua University, Beijing 100084, China Correspondence should be addressed to Li Yanmei (e-mail: liym@mail. tsinghua.edu.cn)
