Intramolecular Aza‐Diels–Alder Reactions of <italic>ortho</italic>‐Quinone Methide Imines: Rapid, Catalytic, and Enantioselective Assembly of Benzannulated Quinolizidines.

Abstract: Aza‐Diels–Alder reactions (ADARs) are powerful processes that furnish N‐heterocycles in a straightforward fashion. Intramolecular variants offer the additional possibility of generating bi‐ and polycyclic systems with high stereoselectivity. We report herein a novel Brønsted acid catalyzed process in which <italic>ortho</italic>‐quinone methide imines tethered to the dienophile via the N substituent react in an intramolecular ADAR to form complex quinolizidines and oxazinoquinolines in a one‐step process. The reactions proceed under very mild conditions, with very good yields and good to very good diastereo‐ and enantioselectivities. Furthermore, the process was extended to a domino reaction that efficiently combines substrate synthesis, <italic>ortho</italic>‐quinone methide imine formation, and ADAR. [ABSTRACT FROM AUTHOR]