Pyrrolo diazepinone

The pyrrole derivative of carbonyl azide 206 undergoes thermal Curtius rearrangement into isocyanate, which spontaneously cyclizes into pyrrolo-diazepinone 207 (Equation (27) (1991JHC1911)). 

A two-step route to tetrahydrobenzo[b]pyrrolo[3,4-e][l,4]diazepinone 241 (X = NH) starting from 4-hydroxy pyrrolone 240 has been reported (Scheme 51 (1991KFZ16)). 

Debenzylation on the side-chain with TMSl to produce substituted benzo[/]pyrrolo[l,2-d][l,4]diazepinone 181 has been reported (Scheme 36, Section 3.1.1.1 a992BMCL1639)). 

Diazepines have attracted considerable attention in 1980, as befits their commercial importance as antidepressents and in other medicinal applications. Work appeared from Roche describing further investigations into the industrial preparation of the antidepressants, and another group prepared a pyrrolo-benzo[l,4]diazepinone in an analogous manner.Possibly of more interest were two reports on the preparation of 1,3-diazepines which are not so common. Ishikawa et reported the synthesis of (424) by standard methods, and Coyle etal produced (426) by acid-catalysed cyclodehydration of the hydroxy-benzamide (425) in >80% yield. Phthalimide Mannich bases have been widely investigated by several groups in analogous conversions as discussed earlier. 

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