Sarah E Reisman
A Unified Strategy to ent-Kauranoid
Natural Products
2014/1/11
M1 Takahiro Shrai
1
Index
1.Introduction
2.Direction
2-1 Strategy
2-2 Project
3.Total synthesis
3-1 (−)-maoecrystal Z
3-2 (−)-Trichorabdal A, (−)-longikaurin E
4.Summary
4-1 (−)-maoecrystal Z
4-2 (−)-Trichorabdal A, (−)-longikaurin E
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Sarah E Reisman
Curriculum vitae
2008
Assistant professor.
California Institute of Technology, Pasadena, CA
2006-2008
NIH Postdoctoral Fellow. with Professor Eric N. Jacobsen
Harvard University, Cambridge, MA
2002-2006
Ph.D. with Professor John L. Wood
Yale University, New Haven, CT
1999-2001
B.A. with Professor Timo V. Ovaska
Connecticut College, New London, CT
Award
Tetrahedron Young Investigator Awards 2014
Reisman’s Group Home Page
http://reismangroup.caltech.edu/aboutSarah.html
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Her Strategy
4
Her Project
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Bioactivity
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Synthetic Features
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Total Synthesis of (−)-Maoecrystal Z
Key reaction
1.Sm(II)-mediated cascade cyclization
2.Ti(III)-mediated reductive coupling
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Retro Synthesis of (−)-Maoecrystal Z
Sarah E. Reisman, et al. J. Am. Chem. Soc. 2011, 133, 14965.
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Preparation of Spirolactone
Ti(III)-mediated Reductive Coupling
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Diastreoselectivity in Addition
Chem.−Eur. J. 2003, 9, 531.
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Preparation of Reductive Cyclization
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Sm(II)-Mediated Reductive Cyclyzation
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Reductive Cascade Cyclization
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Sm Cascade Cyclization
• Precedent
Dialdehyde Cascade cyclization
• Protonation solvent
Difference of alcohol solvent
• Additive’s role
LiCl or LiBr
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Dialdehyde Cascade Cyclization
David J. Procter. et al. Tetrahedron. 2009. 65. 10816
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Dialdehyde Selectivity
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Protonation Solvent Effect
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David J. Procter. et al.Org. lett. 2003, 4811.
LiCl and LiBr Play an Important Role
Robert A. Flowers. et al, J. Am. Chem. Soc. 2000, 122, 7718.
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Completion of The Synthesis of
(–)-Maeocrystal Z
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Summary (1)
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Total Synthesis
(−)-Trichorabdal A, (−)-longikaurin E
Key reaction
Sm(II)-mediated cascade cyclization
Pd(II)-mediated oxidative cyclization
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Retro Synthesis of (−)-Trichorabdal
and Longikaurin E
Sarah E. Reisman, et al. J. Am. Chem. Soc. 2013, 135, 11764.
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Synthesis of an Oxidative
Cyclization Substrate
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Pd(II)-Mediated Cascade Cyclization
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Pd(II)-Mediated Cascade Cyclization
Silyl Enol Ether and Solvent Effect
Synlett. 2002, 8, 1211.
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Mechanism of Pd(II) cascade cyclization
Synlett. 2002, 8, 1211.
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Total Synthesis of (–)-Trichorabdal A
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Total Synthesis of (–)-longikaurin E
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Summary(2)
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Proposed Reactive Conformation
Bryant H. Yang, et al ,J. Am. Chem. Soc. 1997, 119, 6496.
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Mono Deacetylation
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Reduction Potential
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Optimization of Oxidative Cyclization