Synthesis and antimicrobial activity of 2-（3＇, 5＇-disubstituted-indoly-2＇-yl）-4H-3, 1-benzoxazin-4-ones and their derivatives

As benzoxazin-4-ones and quinazolines linked to indole nucleus acting as a good pharmacophore, the synthesis of these compounds has significant meaning. The key intermediates 2-（2＇, 5＇-disubstituted-indol-2＇-yl）-4H-3, 1-benzoxazin-4-ones （3） were synthesized from cyclocondensation of indole-2-carbonyl chlorides （2） and anthranilic acid. Compound （3） on reaction with thiosemicarbazide and o-phenylene diamine afforded the compound （4） and （6） respectively. Compound （4） subjected to intramolecular cyclization under thermal conditions above its melting point afforded the compound （5）. Similarly compound （3） on fusion with o- phenylene diamine gave compound （7）. Structures of these compounds were confirmed by their spectral studies. The compounds were screened for their antimicrobial activity and the results were reported.