Benzazepines derivatives Beckmann rearrangement

A Beckmann rearrangement-reduction sequence has been used to access a number of substituted H- 1-benzazepine derivatives, with the required substituted a-tetralone precursors being prepared by a xanthate-based free radical cyclization process <2006BMC6165>. 

The xanthate transfer process provides a simple and uniquely powerful route to a-tetralones, another family of important aromatic derivatives [69-71]. a-Tetralones are starting materials for the synthesis of a host of medicinally important compoimds. They are precursors to naphthalenes, naphthols, naphthylamines, and ring expansion through the Beckmann rearrangement provides access to benzazepine derivatives. The two examples in Scheme 34 illustrate, on one hand, the possibility of preparing a tetralone with a carbohydrate-derived appendage [69] and, on the other, the synthesis of a substituted naphthol 59 by aromatisation of tetralone 58 through acid... 

There are two reports in the literature of the Beckmann rearrangement to obtain 3-benzazepin-2-one. The O-tosyl derivative of 118 (R -R6 = H) was heated in methanol at 100° in a sealed tube to give 34 (R -R10 = H) in 78% yield.129 Irradiation of 122 with a high-pressure mercury lamp gave a low yield of 123 via 124.130... 

The Beckmann rearrangement was exploited for the synthesis of a 1-benzazepin-2-one intermediate in the synthesis of oxindole derivatives (14IJPC436). Triflic acid-mediated cyclization of a nitroacetamide yielded a... 

---