Synthesis and antioxidant activity of substituted-1,3,2-diazaphosphole 1-oxides

Synthesis of 1-substituted-1,3,2-diazaphosphole 1-oxides (3a-l) were accomplished via a two-step process. It involves the preparation of diazaphospholo 1-oxide monochloride intermediate (2) and its subsequent reaction with phenols/amino acid esters in dry THF in the presence of triethylamine at 40-45°C. The structures of newly synthesized compounds were characterized by spectral and elemental analysis. The title compounds were evaluated for their in-vitro antioxidant properties.