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Aza-Claisen-RCM Route to 1-Benzazepine Derivatives
D. Ghosh, L. Thander, S. K. Ghosh, S. K. Chattopadhyay*
University of Kalyani, India
22 January 2009 (online)
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.