合成路线1

Diazotization of the known aniline (I), followed by Sandmeyer reaction with CuCN and KCN afforded nitrile (II). Addition of hydrogen sulfide to (II) in the presence of Et3N in hot DMF led to the thioamide (III). Subsequent alkylation of (III) with methyl triflate gave the intermediate thioimidate (IV), and a further treatment of (IV) with hydrogen sulfide and pyridine provided dithioester (V). Displacement of the methylthio group of (V) by hydrazine yielded thiohydrazide (VI). Finally, cyclization of (VI) to the target thiadiazole was achieved upon refluxing in formic acid.