ORGN 710 |
| Fomannosin is a sesquiterpene isolated in 1967 from wood-rotting fungus, Fomes annosus. It features a unique highly strained methylene cyclobutene functionality and is unstable. The zirconocene-mediated ring contraction reaction of 4-vinylfuranosides to highly substituted chiral cyclobutanes was applied to the total synthesis of fommannosin. Starting from D-glucose, the chiral tetra-substitued cyclobutanol 10 was obtained in 15 steps. The cyclopentene ring was constructed employing a RCM reaction. The lactone ring was then installed through a Knoevenagel condensation. Introduction of the cyclopentanone was accomplished through a dihydroxylation, oxidation and SmI2 mediated α-dehydroxylation reaction sequence. The first dehydration was effected through a cyclic sulfite. A second dehydration is needed to finish the asymmetric synthesis of fommannosin.
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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 |
