Synthesis of Azo-Linked Bis Coumarinyl Methanes Using [DBU] OAc Ionic Liquid at Room Temperature

An environmentally benign, effective, new and simple protocol for the synthesis of azo-Linked bis coumarinyl methanes by a nucleophilic addition reaction of synthesized aldehyde and two equivalents of 4-hydroxy coumarins in the presence of 2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a]azepin-1-ium acetate ([DBU]OAc) as a ionic liquid under stirring in room temperature was reported. All reactions are performed in the absence of solvent in high to excellent yield during short reaction times. Further, the ionic liquid can be reused and recovered for several times without loss of activity. This work consistently has the other advantages such as mild reaction condition and simple work-up procedures. There are ten derivatives of azo-linked bis coumarinyl methanes were synthetized. All of synthesized compounds were characterized by IR, 1H NMR, 13C NMR spectroscopy and elemental analysis.