BEHAVIOUR OF 2-SUBSTITUTED 6,8-DIBROMO-3,1-BENZOXAZIN-4-ONES TOWARDS o-PHENYLENEDIAMINE AND ANTHRANILIC ACID; A CASE OF UNUSUAL CLEAVAGE OF 6,8-DIBROMO-2-METHYL-3,1-BENZOXAZIN-4-ONE

Article abstract of DOI:10.1016/S0040-4020(01)86005-1

6,8-Dibromo-2-methyl-3,1-benzoxazin-4-one (1) reacts with o-phenylenediamine to give a mixture of 3,5-dibromoanthranilic acid (2), 2-methylbenzimidazole (3) and 3-(o-aminophenyl)-6,8-dibromo-2-methylquinazolin-4-one (4).However, when the reaction was conducted in ethanol or in the absence of solvent at elevated temperature, a mixture of (2) and (3) was obtained.A similar cleavage of (1) took place when it was allowed to react with anthranilic acid yielding a mixture of (2) and N-acetylanthranilic acid (6).The reaction of o-phenylenediamine with 6,8-dibromo-2-phenyl-3,1-benzoxazin-4-one (7) proceeded normally to give 3-(o-aminophenyl)-6,8-dibromo-2-phenylquinazolin-4-one (8) or 2-benzoylamino-3,5-dibromo-N-(o-aminophenyl)benzamide (9), depending upon the reaction conditions.