Nanoporous TiO2 containing an ionic liquid bridge as an efficient and reusable catalyst for the synthesis of N,N′-diarylformamidines, benzoxazoles, benzothiazoles and benzimidazoles†
In this work, a green and efficient procedure is reported for the preparation of N,N'-diarylformamidines, benzoxazoles, benzothiazoles, and benzimidazoles using nanoporous TiO2 containing an ionic liquid bridge. This reagent is prepared via the modification of nanoporous TiO2 with bis-3-(trimethoxysilylpropyl)-ammonium hydrogen sulfate (TiO2-[bip]-NH2+ HSO4−). The procedure gave the products in excellent yields in very short reaction times under solvent-free conditions. The reusability of the catalyst is the other important feature of the reported method.