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 were obtained in good to excellent yields within short reaction time by condensing dimedone, aldehydes and malanonitrile or ethylcyanoacetate using a catalytic amount of (diacetoxyiodo)benzene as hypervalent iodine in aqueous ethanol under reflux conditions have been discussed. This aqua mediated Knoevenagel-cyclocondensation of various aromatic and hetero-aromatic aldehydes along with the aldehydes like aryl-sulphonyloxybenzaldehyde, aryl-carbonyloxybenzaldehyde also leads to the product under the same reaction conditions. High yields, shorter reaction times, one pot condensation, operational simplicity, easy work-up, purification of products by non-chromatographic methods are some additional features of the present protocol.