Ultrasound-promoted synthesis of polysubstituted imidazole-linked benzoxazole derivatives and the investigation of their optical properties

A rapid and efficient synthesis of novel hybrid imidazole-benzoxazole derivatives is described under ultrasound irradiation. These reactions were carried out through a cyclization reaction of polysubstituted imidazole-based oaminophenols and various benzoic acids in polyphosphoric acid. The starting o-amiophenols were synthesized from corresponding o-nitrophenols using Fe powder in EtOH and acetic acid. o-Nitrophenol derivatives were synthesized from related phenols by employing HNO3 in acetic acid. Structures of the newly obtained products were confirmed by spectral and analytical data. The optical properties of the products were investigated via UV-Vis absorption and fluorescent emission spectroscopy in dilute ethanol solution.