The dearomative (4 + 3) cycloaddition reactions of 3-alkenylindoles
with in situ-generated oxyallyl cations furnish cyclohepta[b]indoles, functionality-rich frameworks found in many bioactive
compounds, including all pentacyclic ambiguine alkaloids. The analogous
reactions between oxyallyl cations and 3-alkenylpyrroles afford cyclohepta[b]pyrroles. The cycloadducts are generally formed in good
to high yields and diastereoselectivities and can be readily transformed
into useful derivatives. Additionally, we report preliminary investigations
into the enantioselective catalysis of the dearomative (4 + 3) cycloaddition
using imidodiphosphorimidate catalysts.