A facile access to the synthesis of highly functionalized novel 4H-pyrano [2′,3′:4,5]imidazo[1,2-a]pyridine hybrid via one-pot four-component domino reaction

A facile one-pot four-component domino protocol has been successfully developed for the combinatorial synthesis of novel N-methyl-3-nitro-4-aryl-4H-pyrano[2 ',3 ':4,5]imidazo[1,2-a]pyridine-2-amine 7 and 2-amino-4aryl-4H-pyrano[2 ',3 ':4,5]imidazo[1,2-a]pyridine-3-carbonitrile 8. The protocol employs readily available starting materials, leading to high yields of the products (83-89%). The transformation involves a domino Knoevenagel-intramolecular Michael reaction sequence, enabling the formation of three new bonds (two C-C, two C-N, and one C-O) and two rings in a single step. Notably, this reaction exhibits several remarkable features, including short reaction time, eliminating the need for extensive workup and column chromatographic purification. Additionally, the reaction demonstrates good scalability, producing satisfactory yields even on a gram-scale.