Mn(III)-pentadentate Schiff base complex supported on multi-walled carbon nanotubes as a green, mild and heterogeneous catalyst for the synthesis of tetrahydrobenzo[b]pyrans via tandem Knoevenagel-Michael cyclocondensation reaction

Mn(III)-pentadentate Schiff base complex supported on multi-walled carbon nanotubes as a recyclable and reusable, green and nano-heterogeneous catalyst was designed and fully characterized using infrared spectroscopy, X-ray diffraction, scanning electron microscopy, , inductively coupled plasma mass spectrometry, and thermogravimetric analysis. A facile, eco-friendly, mild and green procedure was developed for the one-pot three-component synthesis of tetrahydrobenzo[b]pyrans via tandem Knoevenagel-Michael cyclocondensation reactions between aromatic aldehydes, 1,3-diones and malononitrile using a catalytic amount of Mn(III)-pentadentate Schiff base complex supported on MWCNTs as an efficient recyclable heterogeneous catalyst under solvent-free conditions at room temperature. This process has the advantages of easy availability, stability, recyclability and eco-friendliness of the catalyst, short reaction times, high to excellent yields and simple work-up procedure.