Palladium supported on alumina as a highly active heterogeneous catalyst for direct arylation of 6-substituted imidazo[2,1-b]thiadiazole via C H bond activation reaction

• Direct C H arylation. • Heterogeneous catalysis. • Ligand-free. • Highly recyclable catalyst. • Green media. Fast, atom-economical, phosphine-free, and eco-friendly microwave-irradiated reactions permitting the “green synthesis” of 5,6-disubstituted imidazo[2,1- b ]thiadiazole derivatives using heterogeneous palladium catalyst in triethylammonium 2-(1,1-dioxido-3-oxobenzo[ d ]isothiazol-2(3H)-yl)acetate ([Et 3 NH][Sac-CH 3 CO 2 ]) ionic liquid via C H bond activation reaction of 6-substituted imidazo[2,1- b ]thiadiazole derivatives, are reported. This method provides a straightforward route to a wide variety of substituted imidazo[2,1- b ]thiadiazoles and has the advantages of reusability of the heterogeneous catalyst, simple methodology, high yields, and easy work-up.