Three component one-pot synthesis of 4H-benzo-[b]-pyran derivatives using [(diacetoxyiodo)benzene] (DIB) as a hypervalent iodine catalyst

The three components one pot synthesis of 2-amino-4H-benzo-[b]-pyran derivatives wereobtained in good to excellent yields within short reaction time via the condensation reaction ofdimedone, aldehydes and malanonitrile or ethylcyanoacetate using the catalytic amount of[(diacetoxyiodo)benzene] (DIB) as hypervalent iodine in aqueous ethanol under refluxconditions have been discussed. This aqua mediated knoevenagel-cyclocondensation of variousaromatic and hetero-aromatic aldehydes along with the aldehydes like arylsulphonyloxybenzaldehyde,aryl-carbonyloxybenzaldehyde also leads to the product under thesame reaction conditions. High yields, short reaction times, one pot condensation, operationalsimplicity, easy work-up, and purification of products by non-chromatographic methods aresome additional features of the present protocol.

Keywords:

4H-benzo-[b]-pyran , hypervalent iodine , aldehydes , dimedone , multi-componentreaction , aqueous alcohol