Dimethylformamide → (2Z)-2-(5-amino-1,2,4-thiadiazol-3-yl)-2-methoxyiminoacetyl chloride

In 80.0 ml of acetonitrile, 10.0 g of 2-(5-amino-1,2,4-thiadiazol-3-yl)-2(Z)-methoxyiminoacetic acid were stirred at -20° C., followed by the dropwise addition of a chlorinating reagent, which had been prepared beforehand by gradually adding 8.4 g of phosphorus oxychloride at 5° C. to a mixture of 25 ml of acetonitrile and 4.0 g of N,N-dimethylformamide (DMF) and then reacting them for 30 minutes. After they were reacted for 5 minutes, 200 ml of ice water were poured into the reaction mixture to precipitate crystals. The crystals were collected by filtration, washed with 100 ml of ice water and then stirred for 30 minutes in 100 ml of n-hexane. After filtration, the resulting crystals were dried under reduced pressure, whereby the title compound was obtained. Yield: 8.90 g (81.6%). Purity: 97.9%.