Formation of Seven-Membered Cycles

As already mentioned, the increase in the ring size goes along with an enhanced preference for the g ifo-cyclization mode. In the case of seven-membered rings, one seems to have reached the summit, as there are approximately equal amounts of exo- and endo-cyclization cases reported in the literature. 

Finally, Ohishi and coworkers [149] reported the synthesis of novel furo[2,3,4-jA ][2]benzazepin-4(3//)-one derivatives via 7- ndo-cyclization in modest to good yields. 

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