Synthesis, Spectral Characterization and Biological Evaluation of Some Novel Phosphorus Compounds Containing Pyranopyrazole Moiety

Abstract

We displayed the synthesis of some novel bioactive polycyclic compounds formed of 3-methyl-1,4-diphenyl-1,4-dihydropyrano[2,3-c]pyrazole fused with 1,2-azaphosphole and 1,3,2-diazaphosphinines or bearing phosphonate moieties in one molecular frame which showed enhanced biological activity. The methodology depended on treating the 6-amino-3-methyl-1,4-diphenyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile with some phosphorus esters, phosphorus sulfides and phosphorus halides under different conditions. All obtained products were characterized by spectroscopic methods and elemental analysis. In addition, all the synthesized products were evaluated in vitro for their antimicrobial and antioxidant activities. The starting substrate 6-amino-3-methyl-1,4-diphenyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile (3) was synthesized in good yield through the treatment of 3-methyl-1-phenyl-5-pyrazolone (1) with 2-benzylidenemalononitrile (2) in distilled water containing a catalytic amount of sodium benzoate (Scheme 1). The chemical reactivity of this substrate towards some electrophilic and nucleophilic phosphorus reagents was investigated. This provided wide opportunities for the construction of different phosphorus compounds containing the bioactive pyrano[2,3-c]pyrazole.