SNAr versus Buchwald–Hartwig Amination/Amidation in the Imidazo[2,1‐b][1,3,4]thiadiazole Series

An original and efficient palladium-catalyzed amination of imidazo[2,1-b][1,3,4]thiadiazole is reported. The SNAr and Buchwald–Hartwig cross-coupling reactions were investigated to access C-2 aminated imidazo[1,2-b][1,3,4]thiadiazole derivatives. The reaction conditions were optimized under microwave irradiation, and a wide range of amines were used to determine the scope and limitations of the method. To complete this study, the palladium-catalyzed and SNAr amination reactions were compared to determine the best strategy. The X-ray crystallographic data of imidazo[2,1-b][1,3,4]thiadiazole derivative 20 was used to formally establish the structures of the products.