近年来，自由基稳定性的取代基效应，尤其是推拉效应，引起了人们的重视[1－6]．推拉效应是指在同一碳原子上同时连有吸电子基团和推电子基团的自由基而具有额外的稳定性．此效应可直接影响自由基的反应速率、选择性、产率及反应机理．氨基酸是生物体中一类重要的分子，同时包 In recent years, the substituent effect of free radical stability, especially the push-pull effect, has aroused people’s attention [1-6]. Push-pull effect refers to the same carbon atoms with both electron-withdrawing groups and electron groups to promote the radical with additional stability. This effect can directly affect the free radical reaction rate, selectivity, yield and reaction mechanism. Amino acids are a class of important molecules in organisms, all at the same time