A one-pot three-component domino protocol for the synthesis of penta-substituted 4H-pyrans

A library of novel 2-(1H-indol-3-yl)-6-(methylamino)-5-nitro-4-aryl-4 H-pyran-3-carbonitriles and 6-(methylamino)-4-(aryl)-5-nitro-2-phenyl-4H-pyran -3-carbonitriles were synthesized in excellent yields via domino one-pot three-component reactions of 3-(1H-indol-3-yl)-3-oxopropanenitrile or benzoylacetonitrile, aromatic aldehydes and (E)-N-methyl-1-(methylthio)-2-nit roethenamine respectively. This reaction presumably occurs viadomino Knoevenagel condensation-Michael addition-intramolecular O-cyclization sequence of reactions. The significant advantages of this reaction include one-pot process, simple work-up procedure, excellent yields and no column chromatographic purification.