Synthesis of 5-substituted-2-thiohydantoin derivatives under microwave irradiation

Eleven 5-substituted-2-thiohydantoin derivatives were synthesized by a two-step reaction of ammonium thiocyanate with α-amino acids under microwave irradiation. The structures of intermediate products and final products were characterized by ¹H NMR, IR spectra and elemental analysis. Compared with conventional heating method, microwave irradiation possessed such advantages as short reaction time (4 min), high yield of each step (85%-93%). In the meantime, the reaction course of synthesis of compound 2h was discussed.