Dearomative (4 + 3) Cycloaddition Reactions of 3-Alkenylindoles and 3-Alkenylpyrroles to Afford Cyclohepta[]indoles and Cyclohepta[]pyrroles.

The dearomative (4 + 3) cycloaddition reactions of 3-alkenylindoles with in situ-generated oxyallyl cations furnish cyclohepta[]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[]pyrroles. The cycloadducts are generally formed in good to high yields and diastereoselectivities and can be readily transformed into useful derivatives.