The 2-methoxyiminoacyl-mediated arylation of substituted phenylalanines has been examined. Selective monoarylation at the ortho position was achieved using pyridone ligands which decelerate the arylation process. Density functional theory (DFT) study of a continuous C-H arylation process that included the first and second arylation stage was performed. The computational result shows that the introduction of a pyridone ligand obviously disfavors the second arylation stage, which directly contributes to the selectivity between the mono/diarylated products. Furthermore, results of the kinetic isotope effect and a control experiment are agreed with DFT study.