Rapid, Eco-friendly, and One-pot Synthesis of New Lariat Ethers Based on Anthraquinone by Using ZnO Nanoparticles via Mannich Reaction under Solvent-free Condition

High yielding preparation of structurally different anthraquinone lariat ethers from the reaction of a novel anthraquinone aza crown ether 3 with a variety of substituted phenols and paraformaldehyde in the presence of zinc oxide nanoparticles at 100 degrees C in a solvent-free condition has been described. The procedure of these reactions is very simple, the yields are generally high to excellent, and the method is applicable to large scale operation without any problem. Furthermore, the zinc oxide nanoparticles could be recovered and recycled up to five times by simple filtration of the reaction mixture.