Microwave-assisted TsOH/SiO2-catalyzed one-pot synthesis of novel fluoro-substituted coumarin hydrazones under solvent-free conditions

Abstract Sixteen novel fluoro-substituted coumarin hydrazones were synthesized from a series of ethyl 2-hydroxy-2-(trifluoromethyl)-2 H -chromene-3-carboxylates with supported acid catalyst under microwave-assisted one-pot and solvent free conditions. The structures of synthesized compounds were confirmed by IR, 1 H NMR, 13 C NMR, HRMS and single crystal X-ray diffraction. Compared with the reported reaction conditions, the new method has the advantages of shorter reaction time, simple work-up procedure and environmental friendliness. The supported catalyst can be recovered easily and reused with little change in its activity.