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). This was cyclized to the required thiadiazole (VII) upon treatment with 3-carbomethoxypropionyl chloride (A) in refluxing THF. Aminolysis of the ester group of (VII) with methanolic ammonia at 100 C in a sealed vessel provided amide (VIII). This was finally dehydrated to the title nitrile using trifluoroacetic anhydride and pyridine.