Dibenzo oxazepin-6 -ones

The unstable dibenz[c,/][l,2]oxazepines (312 R = CN, Cl) have been isolated as the major products of the UV irradiation of 9-cyano- and 9-chloro-acridine 10-oxides (310) in benzene (c/. the analogous Af-imide to 1,2-diazepine conversion on p. 598). Although none of the oxaziridine tautomer (311) was detectable by UV spectroscopy, the subsequent deoxygenation of (312) to acridine suggests the existence of a thermal equilibrium between (311) and (312) (79T1273). These dibenzo compounds (312) are the only fully unsaturated oxazepines yet isolated but the 2,3-benzoxazepin-l-one system (314) has recently been prepared by the reaction of benzonitrile oxide with the benzopyranone (313) (80JCS(Pl)846). 

There is one possible dibenz-fused system for each of the 0, N and S, N rings. These are the dibenz[c /][l,3]oxazepine (9) and the dibenzo[fi /][l,3]thiazepine (10). Bridged systems incorporating 1,3-oxazepine or 1,3-thiazepine moieties have not been included in this chapter. 

The hypervalent-iodine-mediated tandem reaction process, reported for preparation of benzodiazepinones, when applied to 2-hydroxy-AT-arylben-zamides 92 afforded dibenzo[d,/][l,3]oxazepin-6(7fi)-ones 93 (14AGE6216). 

In a highly regioselective, one-pot, copper-catalyzed UUmann—Smiles cyclization process, 2-halophenols 157 and 2-(2-halophenyl)-lH-indoles 158 reacted to efficiently yield indole-fused dibenzo[l>j/][l,4]oxazepines 159. When 2-(2-bromophenyl)-lH-benzimidazole and 2-bromo-4-chlo-rophenol were used as substrates, the corresponding imidazole-fused dibenzo[l)j/][l,4]oxazepine 160 was formed in high yield (13CC701). 

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