Azepine, geometrical isomers

Spongiacidins A (197) and B (198), azepine-type bromopyrrole alkaloids from Hymeniacidon which are geometrical isomers of hymenialdisine (171), inhibit c-erbB-2 kinase (IC50 9.0 and 8.5 pg/ml) and cyclin dependent kinase 4 (IC50 32 and 12 pg/ml) [157],... 

Two other azepine syntheses involving the interconversion of valence isomers are worthy of note, namely the isomerization of the novel 7-azatetracycloheptane (261), prepared from benzvalene as indicated in Scheme 34, to l-phenyl-l//-azepine (79TL1553) and the rearrangement of the syn isomer of the 2-azatricycloheptane (70 H in place of D), which at 120 °C yields 1 -ethoxycarbonyl-2,3-dihydro- 1H-azepine by a [ 2 +v4t] concerted process. As expected, the anti isomer, for which a concerted process would require a geometrically unfavoured [ 2, + w4a] process, rearranges only at 350 °C, and then by a non-concerted polar reaction (73JA7320). 

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