Synthesis and Reactions of Some Novel 4H-3,1-Benzoxazinone Bearing Chalcone Moiety with Antibacterial Evaluation

Abstract

2-[3-(4-Methoxy-3-methylphenyl)-3-oxoprop-1-enyl]-4H-3,1-benzoxazin-4-one 2 was synthesized by the cyclization of the respective N-acylanthranilc acid 1. The bromination of benzoxazinone 2 afforded the dibromo anthranilic acid 3, which gave N-pyrazolyl anthranilic acid 4 on treatment with hydrazine. The ethanolysis of benzoxazinone 2 with sodium ethoxide gave ethyl anthranilate derivative 5 which on treatment with amines furnished the corresponding ethyl N-substitutedanthranilate 6a-b. The aminolysis of benzoxazinone 2 with ammonium acetate, primary amines and/ or secondary amines afforded the corresponding amides 7a-c and 8a-b. The treatment of benzoxazinone 2 with 2-aminophenol and/ or o-phenylendiamine gave the corresponding 3-(benzooxazol-2-yl) propenone 9 and 3-(benzimidazol-2-yl) propenone 10, respectively. 3-Thiourido-3(4H)-quinazolinone derivative 11 was obtained on the treatment of benzoxazinone 2 with thiosemicarbazide. The reaction of the benzoxazinone 2 with hydroxylamine hydrochloride furnished the corresponding 3-hydroxy-2-isooxazoline-5-yl-4(3H)-quinazolinone 12. The synthesized compounds were screened against strains of bacteria and showed mild to moderate activity towards both gram-positive bacteria and gram-negative bacteria.