Studies On The Asymmetric Synthesis Of Bioactive Hydrodibenzofuran Alkaloids

This thesis mainly concerns the studies of the new synthetic strategy for the catalytic asymmetric construction of all-carbon quaternary stereocenters, which was used for the asymmetric synthesis of bioactive hydrodibenzofuran alkaloids.PartⅠ:Based on a strategically diversity-oriented retrosynthetic analysis, a catalytic asymmetric intermolecular Michael addition as the key step was designed for the asymmetric synthesis of bioactive hydrodibenzofuran alkaloids.PartⅡ:Aiming at the key step mentioned above, we developed a new synthetic strategy for the organocatalytic enantioselective construction of all-carbon quaternary stereocenters via tertiary amine-thiourea catalyzed Michael addition ofα-cyanoketones as donors and acrylates as acceptors. The Michael addition products with moderate to good enantioselectivity were afforded, and also the detailed investigations on the proposed reaction mechanism were also conducted.PartⅢ:Using the key Michael addition we developed, the enantioselective synthesis of (-)-galanthamine and (-)-lycoramine was accomplished successfully.PartⅣ:Employing this novel Michael addition, we also achieved the asymmetric synthesis of (+)-lunarine for the first time.