Asymmetric Synthesis of the Pentacyclic Framework of Kopsia Alkaloids
Yeonghun Song1, John Park1, Sanghee Kim1
1College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 08826, Korea.
Abstract:
Pyrroloazocine alkaloids from the Kopsia genus exhibit structural complexity and pharmacological potential. We report the concise and asymmetric synthesis of a pentacyclic core from l-proline. The key features include a C-N-C chirality transfer process to prepare the α-tertiary amine intermediate enantioselectively, an eight-membered C ring-forming Friedel-Crafts reaction at the indole C3 position, and a dearomative indole-Claisen rearrangement to form a bridged pentacyclic scaffold. This study provides a versatile platform for the divergent synthesis of diverse Kopsia alkaloids.
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