Anthraniloylanthranilamide (o-amino-N-(o-carbamoylphenyl)benzamide): Preparation and use as a synthetic precursor for quinazolino[1,2,3]benzotriazinones

Abstract

Several synthetic routes to anthraniloylanthranilamide (6) are described; the problems involved in o-aminobenzoylation reactions are explored. Reduction of N-(o-nitrobenzoyl)anthranilamide by stannous chloride gave a low yield of 6, which was also obtained in low yield by reaction of isatoic anhydride with o-aminobenzamide. The possible use of O-(o-aminobenzoyl)hydroxylamines for o-aminobenzoylation was investigated but proved impractical. Diazotisation of 6 affords 3-(o-carbamoylphenyl)-1,2,3-benzotriazin-4(3H)-one (2), which undergoes base-catalysed cyclisation to the quinazolino[3,2-c]benzotriazine (4). The conversion 2 → 4 probably involves the isomeric quinazolino[1,2-c]benzotriazine (3), which could not be isolated.