Intramolecular Aza‐Diels–Alder Reactions of ortho‐Quinone Methide Imines: Rapid,Catalytic, and Enantioselective Assembly of Benzannulated Quinolizidines |
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Authors: | M. Sc. Martin Kretzschmar M. Sc. Fabian Hofmann M. Sc. Daniel Moock Prof. Dr. Christoph Schneider |
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Affiliation: | Institut für Organische Chemie, Universit?t Leipzig, Leipzig, Germany |
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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 ortho‐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, ortho‐quinone methide imine formation, and ADAR. |
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Keywords: | asymmetric synthesis Brø nsted acid catalysis nitrogen heterocycles organocatalysis quinone methide imines |
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