General procedure for the synthesis of 5-methyl-1,3,4-oxadiazol-2-amine from 2-acetylhydrazinecarboxamide: 1.17 g (9.99 mmol) of 2-acetylhydrazinecarboxamide was suspended in 23 mL of dimethoxyethane, and 1.68 g (10.96 mmol) of phosphorochloride was added. The reaction mixture was stirred at 70 °C for 2 hours. Upon completion of the reaction, the solvent was removed by distillation under reduced pressure. To the residue, 10 mL of water and 100 mL of ethyl acetate were added, followed by the addition of sodium carbonate to adjust the pH of the aqueous phase to 8. The mixed solution was extracted with ethyl acetate (100 mL x 2), and the organic layers were combined and dried over anhydrous sodium sulfate. The organic solvent was removed by distillation under reduced pressure to give 0.50 g of 5-methyl-1,3,4-oxadiazol-2-amine as a white solid.
