Aza-Claisen-RCM Route to 1-Benzazepine Derivatives

Significance

Reported is a protocol for the ­synthesis of 1-benzazepine derivatives. The sequence includes bis-allylation of anilines followed by a Lewis acid mediated aza-Claisen rearrangement. After N-protection, the N,2-diallylanilines formed are subjected to ring-closing metathesis conditions using Grubbs I catalyst to give the ­target 1-benzazepines. The aza-Claisen rearrangement was highlighted as a key step, the best results being achieved under refluxing chloro­benzene in the presence of BF₃˙OEt₂. However, the experimental details were not provided. The procedure was applied for the synthesis of simple benzazepine derivatives as well as heteroannulated analogues, both in fair to good yields.