Efficient synthesis of SCF3-substituted tryptanthrins by a radical tandem cyclization.

Herein, we report a new, efficient and atom-economical strategy for the synthesis of SCF3-substituted tryptanthrin derivatives. These previously unreported derivatives were obtained by means of a radical tandem cyclization. The reaction was triggered by addition of a SCF3 radical to a carbon-carbon double bond and involved the formation of a C(sp3)-SCF3 bond, a C(sp2)-C bond, and a C(sp2)-N bond. This method has mild conditions and a wide range of substrates which is particularly useful for the preparation of substituted indolquinazoline derivatives that widely exist in many natural products, but are not easy to obtain by conventional approaches.