Green approach for the synthesis of carboxycoumarins by using a highly active magnetically recyclable nanobiocomposite via sustainable catalysis

An efficient approach was reported for the synthesis of substituted 3-carboxycoumarins via a Knoevenagel condensation reaction between Meldrum's acid and substituted salicylaldehydes in the presence of a magnetic cellulose/Ag catalyst in EtOH at room temperature. This protocol includes many advantages such as remarkable magnetic properties of the nanobiocomposite catalyst, short reaction times, high yields and simple isolation of the organic products. In addition, the nanostructure catalyst can be easily separated from the reaction mixture and reused several times efficiently. Fourier transform infrared spectra, nuclear magnetic resonance spectra, X-ray diffraction pattern and field emission scanning electron microscopy images were performed for the characterisation of the products and the nanocatalyst.