AN EFFICIENT, GREEN, CATALYST FREE SYNTHESIS AND CRYSTALLOGRAPHIC STUDY OF BENZO-4H-PYRANS IN AQUEOUS MEDIUM

A highly efficient and environmentally benign for the synthesis a of 2-amino-7-hydroxy-4-aryl-4H-chromene-3-carbonitrile derivatives (4a-n) in good to high yields (90%-97%) by one-pot three-component Michael addition reaction of malononitrile, aromatic aldehydes and resorcinol under reflux condition was developed in aqueous medium. Single crystal X-ray studies show that 4h crystallizes in the formula C22H15Cl2N2O2, Mr=410.26, Monoclinic, Space group P2(1)/c, a=12.753(9)Å, b=6.665(4)Å, c=24.050(14) Å, β=102.95(3)A° and 4i C16H10Cl2N2O2, Mr=333.16, Triclinic, Space group P-1, a=6.271(3)Å, b=18.697(5)Å, c =13.794(7) Å,  β =94.269(17)A°. The structure of the products were further confirmed by 1H NMR, 13C NMR, IR and Mass spectrum. Keywords: Benzopyrans, malononitrile, resorcinol, Michael addition, water mediated synthesis, single crystal XR

A BENIGN SYNTHESIS OF 2-AMINO-3-CYANO-4H-BENZOPYRANS VIA DOMINO REACTION

A green and operationally simple approach domino reaction has been developed for the synthesis of 2-amino-3-cyano- 4H-chromene derivatives from aromatic aldehydes, resorcinol and malononitrile in aqueous medium. This work represents the first example of catalyst free and organic solvents free multi-component reactions for the synthesis of pharmaceutically important chromene derivatives. The structures of the synthesized compounds were confirmed by 1H NMR, 13C NMR, IR, Mass and single crystal XRD.  Keywords: Benzopyrans, malononitrile, Michael addition reaction, domino reaction, water mediated synthesis