N-substituted amino acid derivatives are synthesized according to the synthetic route shown as follows. Generally, a solution of NaOH and amino acid in THF/H2O (1:1) was cooled to 0°C in an ice bath. N-octanoyl chloride was added dropwise, and the mixture was stirred overnight at room temperature. The residue was quenched by 1M HCl solution and extracted with ethyl acetate, dried over anhydrous Na2SO4. The solvent was removed under reduced pressure and the crude product was washed with ether.