2W-Azepines

In other somewhat related work, the synthesis of pyrano[2,3-c]azepines (and pyrido[2,3-c]azepines has been described. Reaction of hydrazoic with iV-(5,6,7.8-tetrahydro-2,5-dioxo-2W-l-benzopyran-3-yl)benzamide (or 8-hydrazono) derivatives afforded pyrano[2,3-c]azepines, which in turn can be transformed to pyrido[2,3-c]azepines <00H(53)1111>. 

Diene moieties, reactive in [2+4] additions, can be formed from benzazetines by ring opening to azaxylylenes (Section 5.09.4.2.3). 3,4-Bis(trifluoromethyl)-l,2-dithietene is in equilibrium with hexafluorobutane-2,3-dithione, which adds alkenes to form 2,3-bis-(trifluoromethyl)-l,4-dithiins (Scheme 17 Section 5.15.2.4.6). Systems with more than two conjugated double bonds can react by [67t+2tt] processes, which in azepines can compete with the [4tt +2w] reaction (Scheme 18 Section 5.16.3.8.1). Oxepins prefer to react as 4tt components, through their oxanorcaradiene isomer, in which the 4w-system is nearly planar (Section 5.17.2.2.5). Thiepins behave similarly (Section 5.17.2.4.4). Nonaromatic heteronins also react in orbital symmetry-controlled [4 + 2] and [8 + 2] cycloadditions (Scheme 19 Section 5.20.3.2.2). 

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