Background: Molecular hybridization (MH) is currently well-practiced in the rational drug
design and has offered notable success in developing various lead candidates. With the proven pharmaceutical
potentials of 4H-pyrans and indoles, the present work has been conceived to unit these two
potent structural motifs within one molecular architecture by introducing a new protocol that satisfies
several green chemistry aspects.
Method: The aim of this present work is to develop a facile and eco-friendly protocol for the synthesis
of biologically relevant diversely substituted 2-amino-3-cyano-4-(3-indolyl)-4H-chromenes at ambient
conditions. Characterizations of the synthesized compounds have been performed using analytical and
Results: A practical method for the facile one-pot synthesis of a series of pharmaceutically interesting
functionalized 2-amino-4-(indol-3-yl)-4H-chromene-3-carbonitriles has been developed from the sequential
Knoevenagel-cyclocondensation and Michael addition between salicylaldehydes, malononitrile
and indoles in aqueous ethanol at room temperature based on commercially available trisodium
citrate dihydrate as an inexpensive and eco-friendly catalyst.
Conclusion: We have developed a simple, energy-efficient and eco-friendly method for easy access to
such heterocycles of promising interest from a one-pot multicomponent reaction. The mild reaction
conditions at room temperature, good to excellent yields, operational simplicity, absence of tedious
separation procedures, clean reaction profiles, reusability of the reaction media, energy efficiency, high
atom economy, as well as the use of inexpensive and environmentally benign catalyst are the key advantages
of the present method.