Oxidation of 2,3- and 2,5-dihydro-1H-1-benzazepines by hydride transfer to an iminium ion: Synthesis of 3H-1-benzazepines

Article abstract of DOI:10.1016/0040-4020(96)00091-9

Some 3H-1-benzazepines were prepared by dehydrogenation of secondary 2,3- and 2,5-dihydro-1H-1-benzazepines involving a hydride transfer to an iminium ion generated from a heterocylic enamine and BF₃. With 2,5-dihydro-1H-1-benzazepines the initial formation of 5H-1-benzazepines was observed, whose treatment in the presence of BF₃ led to 3H-1-benzazepines. The same rearrangement could be performed with t-BuOK. The hydride transfer was demonstrated using a deuterium labelled substrate. Tertiary dihydro-1-benzazepines was also oxidized but underwent rearrangement to naphthylamine derivatives.