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

In 30.0 ml of tetrahydrofuran (THF), 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 5.43 g of trichloromethyl chloroformate at 5° C. to a mixture of 80 ml of THF and 4.0 g of N,N-dimethylformamide (DMF) and then reacting them for 30 minutes. After they were reacted for 5 minutes, the reaction mixture was poured into 200 ml of ice water to precipitate crystals. The crystals were collected by filtration, washed with 100 ml of ice water, collected by filtration, 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: 9.2 g (84.3%). Purity: 96.5%.