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Synthesis of Discodermolides Useful for Investigating Microtubule Binding and Stabilization. Melissa G. Morris CHEM 635 February 12, 2013. Hung, D. T.; Nerenberg , J. B.; Schreiber, S. L. J. Am. Chem. Soc. 1996, 118, 11054-11080. Stuart L. Schreiber, Ph.D. Born February 6, 1956
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Synthesis of Discodermolides Useful for Investigating Microtubule Binding and Stabilization Melissa G. Morris CHEM 635 February 12, 2013 Hung, D. T.; Nerenberg, J. B.; Schreiber, S. L. J. Am. Chem. Soc. 1996, 118, 11054-11080
Stuart L. Schreiber, Ph.D. • Born February 6, 1956 • B.A. in chemistry from UVA, 1977 • Ph.D. from Harvard University • Joined Yale University faculty in 1981 • Promoted to associate professor in 1984 • Full Professor in 1986 • Retuned to Harvard in 1988–present • Morris Loeb Professor of Chemistry • and Biology • Director of Chemistry Biology • A Founding Member of the Broad • Institute of Harvard and MIT. • His research is focused in chemical biology • >460 publications
History • 1990–isolated by Gunasekera and co-workers at the Harbor Branch Oceranographic Institute from the deep-sea marine sponge Discodermolidedissoluta • 1993–Schreiber and co-workers reported the first total synthesis of Discodermolide, but unfortunately the unantural antipode, (-)-Discodermolide • They also determined the absolute stereochemistry, something Gunasekera was unable to determine
Retro-synthesis • 2 = C-C7 • 3 = C9-C15 • 4 = C16-C24
Forward Synthesis Synthesis of C1-C7 Synthesis of C9-C15
Forward Synthesis Cont. Synthesis of C16-C24
Combining the Fragments C9-C15 Reduction of acetylene was too problematic in the presence of the terminal diene C16-C24
The Final Step… …doesn’t work!
Stereochemistry His original total synthesize provided: ([a]20D = -13.0(c = 0.6, methanol)). The current synthesis provided: ([a]20D = +14.0 (C = 0.6, methanol)), which was obtained via biological characterization
Synthesizing Derivatives for Biological Studies • Purpose: To further characterize the interactions between Discodermolide and its receptor • How: Synthesize an array of targets that can be analyzed when subjected invivo • Why:Disocdermolidecomprises numerous biological properties: • Immunisuppressive • Antiproliferative/antimitotic • Potent microtubule-stabilizing agent
Structural Variants for Studying Interactions with Discodermolide Receptor • Before these variants were made, truncated version of Discodermolide were tested to see if the full length is needed for receptor recognition
Structural Variants Cont. • 32 and 35 were not active in vivo, suggesting that the full length of Discodermolide was necessary for receptor recognition
Summary of Reagents and Activities Final Biological Assay Results
Conclusion A total synthesis of (+)-Discodermolide in 36 steps, with an overal yield of 4.3% over 24 steps (the longest linear sequence) Discodermolide remains the most potent natural promoter of tubulin assembly