An unprecedented Lewis acid catalyzed
[4 + 3] cycloaddition reaction
is described that provides a straightforward route to polycyclic products
containing an imine-based indole azepine scaffold, starting from readily
available internal tertiary alkynols and azides. This cycloaddition
protocol provides efficient and atom-economical access to a new class
of fascinating imine-containing products in satisfactory yields, which
has shown good application in the construction of seven-membered <i>N</i>-heterocycles
