Benzo azepine formation

The factors that affect azepine formation versus production of open-chain rearranged compounds by cycloadditions to vinyl-aziridines (discussed in last years report) have been further assessed. The reaction of tetrahydronaphthalene tertiary alcohols with HNg-HgSC has been found to provide a high-yield regiospecific method for the synthesis of tetrahydro-2,3,4,5-benzo[b]-lH-azepines substituted at position 2... 

Construction of the indole ring via Fischer synthesis. Starting from a variety of 3,4-dihydro-lH-benzo[l ]azepine-2,5-diones 40 and arylhydrazines Fischer syntheses of indolo benzazepinones 41 have been reported (Scheme 8 (1999JMC2909)). Usually, the reaction comprises a two-step one-pot procedure with the formation of intermediate arylhydrazones in warm acetic acid followed... 

Several azepine ring constructions have been reported using palladium catalyzed C-C bond formation. Palladium catalyzed cyclizations of substituted tryptamine derivatives 73 lead to benzo[d]pyrrolo[l,2-a]azepinones 74 (Equation (8) (2000JMC1050)). 

Construction of the azepine ring by C-N bond formation. Aranapakam et al. synthesized 5,10-dihydro-4H-benzo[l7]thieno[2,3-e]azepine 111 and 4H-benzo[ 7]thieno[3,2-e]azepin-10(9H)-one 113 (X = CO) starting from the corresponding tributylstannyl derivatives 110 and 112, which react with 2-nitrobenzyl bromide and [(Ph)3P]4Pd. Sequential deprotection and reductive cyclization were carried out in one step with zinc and aqueous acetic acid (Scheme 22 (1999BMCL1733)). 

The ring expansion of aromatic azides, long established as a preparative procedure for azepines, has been applied to the formation of benzo-2,4-diazepines. Photolysis of 4-isoquinolyl azides in the... 

Aryl-aryl cyclizations were used for the preparation of polyaromatic compounds, cryptands and heterocydes. A particularly interesting version is the Still-Kelly cyclization that was used for the synthesis of phenanthro [9,10-d]pyrazoles involving the intermolecular formation of the aromatic stannane followed by an intramolecular coupling with the aryl halide moiety [128]. Benzo [4,5]furopyri-dines [129] and dibenz [c,a]azepines [130] were prepared by related intramolecular coupling of diodides in the presence of hexamethylditin. 

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