Synthesis of the Main Impurities of Vildagliptin

OBJECTIVE To conduct the quality control of an oral antidiabetic vildagliptin, three impurities recorded in quality specifications were prepared.METHODS Impurity A was obtained from vildagliptin(1) by ring-closure reaction. Impurity B was generated in impurity A by hydrolytic reaction. Impurity B and impurity C could be also synthesized from vildagliptin(1), via hydrolytic reaction, esterification and ring-closure reaction. RESULTS The chemical structures of the three impurities were confirmed by LC-MS, ¹H-NMR and ¹³C-NMR. The purities were >97% as determined by HPLC. CONCLUSION The synthesized impurities can be used as the standard substances in the quality control of vildagliptin.