Synthesis and Anti‐Oxidant Activity of (5 E ,9 E )‐16‐(Substituted)‐7,8‐dihydro‐16λ 5 ‐dibenzo[ d , l ][1,3,7,10,2]dioxadiazaphosphacyclotridecine‐16‐ones

A new class of biologically active 13‐membered phosphorus‐macroheterocycles ( 6a – l ) were conveniently synthesized from 1,2‐ bis (salicylidene amino)‐phenylene ( 1 ), by treating with phosporusoxychloride ( 3 ) and followed by reacting with various aromatic thiols and amines ( 5f – l ) in one path, and in another path 1 was directly treated with various phosphorodichloridates ( 2a – e ) in the presence of triethylamine at 0–10°C under N 2 atmosphere in THF. All the title compounds were confirmed by analytical and spectral data (IR, 1 H‐, 13 C‐, 31 P‐NMR, and mass spectra) and screened for anti‐oxidant activity. Among these compounds, 6k , 6e , and 6l containing nitro, fluoro, and chloro groups as substituents on the phenyl ring exhibited high anti‐oxidant activity with effective inhibitory concentration (IC 50 ) values.