One-pot synthesis of 1,3-benzo[d]thiazole derivatives promoted by Al(HSO4)3 under sonication conditions

The presence of an imidazole ring in natural products and pharmacologically active compounds has instituted a diverse array of synthetic approaches to these heterocycles. Very recently, we among many others have demonstrated that heterogeneous reagent systems have many advantages such as simple experimental procedures, mild reaction conditions and minimization of chemical wastes as compared to the liquid phase counterparts. Thus, inorganic acidic salts such as Al(HSO4)3, Mg(HSO4)2 and Zr(HSO4)4 could be recommended for above mentioned purposes. Al(HSO4)3 is an efficient, readily available and cheap catalyst for thesynthesis of 1,3-benzo[d]thiazole derivatives by condensation of 2-aminothiophenol and aldehydesunder sonication conditions.This protocol is very simple with easy workup and good to excellent yieldsof products.