OXIDATION OF 2,3-DIHYDRO-1H-1-BENZAZEPINES AND 2,5-DIHYDRO-1H-1-BENZAZEPINES BY HYDRIDE TRANSFER TO AN IMINIUM ION - SYNTHESIS OF 3H-1-BENZAZEPINES

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