Ultrasound as green process and an alternative energy source was investigated for the environmentally benign synthesis of novel benzoxazoles from different azo-linked salicylic acid derivatives and 2-amino-4-chlorophenol in short reaction time and high yield. These benzoxazole compounds have been characterized by elemental analysis, FT-IR, (1)H NMR and (13)C NMR spectroscopy.

Bis--(butane-1,4-diyl)bis(1,2-dimethyl-1H-imidazole-3-ium)bromide ([BDBDIm]Br) was found to be effective catalyst for the synthesis of novel benzoxazoles using different salicylic acid derivatives and 2-amino-4-chlorophenol at room temperature. The present methodology offers several advantages such as solvent-free conditions, excellent yields, simple procedure, mild conditions and reduced environmental consequences. The ionic liquid was recovered and reused. All of synthesized compounds were characterized by IR, NMR and elemental analyses.

An efficient protocol for the facile synthesis of a series of pyrido[2,3- d]pyrimidine derivatives has been developed applying Fe3O4–ZnO–NH2–PW12O40 nanocatalyst in water. This novel method has the benefits of operational simplicity, green aspects by avoiding toxic solvents and high to excellent yields of products. Fe3O4–ZnO–NH2–PW12O40 was synthesized and characterized by Fourier transform infrared, X-ray diffraction, vibrating sample magnetometer, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy analyses. The nanocatalyst is readily isolated and recovered from the reaction mixture by an external magnet.

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Synthesis of Novel Derivatives of Benzoxazole in Bis-Ionic Liquid [BDBDIm]Br. -The title ionic liquid (IMB) is an effective catalyst for the synthesis of benzoxazoles from 2-hydroxybenzoic acid and 2-aminophenol derivatives by a solvent-free and simple method under mild conditions. -(NIKPASSAND*, M.; ZARE FEKRI, L.; FAROKHIAN, P.; Synth. Commun. 45 (2015) 20, 2303-2310, http://dx.