The general procedure for the synthesis of 5-amino-3-methyl-1,2,4-thiadiazole from potassium thiocyanate and chloroacetamidine was as follows: chloroacetamidine (5.1 g, 55 mmol) was dissolved in methanol (250 mL) and the resulting solution was cooled to 0 °C. Subsequently, potassium thiocyanate (5.3 g, 55 mmol) was added to the solution. The reaction mixture was stirred at room temperature for 12 hours. Upon completion of the reaction, the solution was concentrated under reduced pressure, diluted with ethyl acetate (200 mL) and insoluble solids were removed by filtration under reduced pressure. The filtrate was further concentrated under reduced pressure to give the crude product. The crude product was purified by column chromatography (silica gel, n-hexane:ethyl acetate = 4:1) to afford finally 5-amino-3-methyl-1,2,4-thiadiazole (2 g, 32% yield). The structure of the product was confirmed by 1H NMR (600 MHz, CD3OD), δ 3.27 (s, 3H).
