Sodium Bismuthate: An Efficient Catalyst for the One-pot Synthesis of Biologically Active Spiro[4H-pyran] Derivatives under Solvent-free Conditions

An efficient sodium bismuthate (nabio3) synthesis of biologically active spiro[4h-pyran] derivatives has been accomplished via one-pot three-condensation of isatin/acenaphthequinone, malononitrile and different reagents including 1,3-dicrbonyl compounds, α-naphthol and 4-hydroxycumarin under solvent-free conditions. the notable advantages of the present procedure are: eco-friendly, environmentally benign nature, low-cost and non-toxic catalyst, simplicity of operation with no necessity of chromatographic purification steps, short reaction times, good to high yields and solvent-free conditions.