ORGN 746 |
| The Daphniphyllum alkaloids continue to draw the attention of both synthetic and biogenetic research groups due to their unusual and disparate structural backbones. Recent isolation of the active extracts from D. humile and D. teijsmani have led to the characterization of novel fused hexa- and pentacyclic alkaloids Daphnicyclidins A-H. These novel skeletons possess a common core fused tricycle (labeled as rings A, B, and C) which has been the focus of our synthetic efforts. Synthetic control over the formation of remote quaternary centers has been demonstrated by the use of an intramolecular carbene cyclopropanation. A 1,4-transferrance of chirality from a (+)-limonene derivative sets the absolute stereochemistry of the quaternary center at the A-C ring fusion. Furthermore, a novel cyclopropane ring opening and expansion has been developed, giving rise to the cis- fused A-C ring system. Further development of this chemistry leads to the sterocontrolled synthesis of the fused tricyclic ABC core of the Daphnicyclidins.
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Total Synthesis, Materials, Molecular Recognition, Process R&D, and Physical Organic Chemistry
8:00 PM-10:00 PM, Wednesday, 13 September 2006 Moscone Center -- Hall D, Poster
Division of Organic Chemistry |
