Synthesis of some new functionalized pyrano[2,3-<i>c</i>]pyrazoles and pyrazolo[4′,3′:5,6] pyrano[2,3-<i>d</i>]pyrimidines bearing a chromone ring as antioxidant agents

Abstract

A new series of functionalized pyrano[2,3-c]pyrazoles and pyrazolo[4′,3′:5,6]pyrano [2,3-d]pyrimidines bearing a bioactive chromone ring was achieved. The methodology depended on treatment of 6-amino-4-(4-oxo-4H-chromen-3-yl)-3-phenyl-1,4-dihydropyrano [2,3-c]pyrazole-5-carbonitrile (3) with different electrophilic reagents. All the synthesized compounds were fully characterized by spectroscopic data and screened for their in vitro antioxidant activity using DPPH radical scavenging methods. A preliminary study of the structure–activity relationship revealed that the combination of pyranopyrazole skeleton with pyrimidine moiety along with NH and OH groups enhanced overall the antioxidant properties.