One-pot, catalyst-free synthesis of novel dihydropyrano[2,3-e]indole derivatives

Abstract

A new one pot three-component reaction for the synthesis of dihydropyrano[2,3- e ]indole derivatives has been developed. The synthesis was achieved by reacting 4-hydroxyindole, aromatic aldehydes and ( E )- N -methyl-1-(methylthio)-2-nitroethenamine at 120 °C under neat reaction conditions in Monowave 50 reactor. This transformation involves the formation of pyranoindole ring by creation of two C–C bonds and one C–O bond a single synthetic operation. As the products precipitate out of the reaction simple filtration is sufficient to isolate the pure products and hence, there is no need for work-up or column-chromatography purification.