Synthetic Utilization of Polynitroaromatic Compounds. 3. Preparation of Substituted Dibenz[b,f][1,4]oxazepine-11(10H)-ones from 2,4,6-Trinitrobenzoic Acid via Nucleophilic Displacement of Nitro Groups

1,3-Dinitrodibenz[b,f][1,4]oxazepin-11(10H)-one, prepared by intramolecular displacement of nitro group in N-(2-hydroxyphenyl)-2,4,6-trinitrobenzamide, reacts with O- and S-nucleophiles to yield the products of mono- or bis-substitution of the nitro groups. The nitro group in position 3 is displaced first. This observation is in contrast with earlier results for the nitro-substituted benzoannulated five-membered heterocycles. This difference in reactivity is likely due to the increased steric hindrance for peri-nitro group displacement in the case of the benzoannulated seven-membered heterocycle. N-Alkylation of the nitro-substituted dibenz[b,f][1,4]oxazepin-11(10H)-ones yields analogues of a known antidepressant drug Sintamil. The structure of the products is confirmed by NOE experiments and alternative synthesis.