Abstract: A Study on Mass Spectrometry of 3-Substitutedaryl-Indolyl-2-PhosphonatesJiao Xianyun; Cai Mengshen (School of Pharmaceutical Sciences, Beijing Medical University, Beijing 100083)Peng Jiarou; Zhang Haiyin (Spectral Analysis Laboratory , Analysis and Computation Center,Beijing Medical University, Beijing 100083)Abstract:A study on mass spectrometry of 3 - substitutedaryl - indolyl - 2- phosphonates is reported. An γ - alkyl rearrangement of an alkyl group in phosphonate is also found during electron impacting. The fragmentation characteristic of the compounds (BI ) is studied by using electron impact (EI), electron impact - collision activity - mass analysed ion kinetic energy spectrometry (EI - CA - MIKES) and accurate mass measurment techniques(AMMT). The fragmentation pathway is portrayed in a scheme (see fig2).Keywords:γ-alkyl rearrangement, 3-substitutedaryl-indolyl-2-phosphonates,EI-CA-MIKES