Oxidative Cyclization of 1,5Dienes

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Oxidative Cyclization of 1,5-Dienes

• Jatta Aho
• Laboratory of Organic Chemistry
• HUT

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Contents

• Stereoselection in oxidative cyclization
• THF rings in natural products
• Permanganate promoted oxidative cyclization
• Mechanism
• Asymmetric induction with chiral auxiliaries
• Catalytic methods with other metal-oxo species
• Ruthenium tetroxide
• Osmium tetroxide
• Asymmetric protocol with chiral phase transfer
  catalyst

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Stereoselection

• Oxidative cyclization of 1,5-dienes is a unique
  method for making tetrahydrofuran rings
• Stereospecific addition of two oxygen atoms
• Stereoselective formation of a cis-substituted
• THF ring

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THF ring in Natural Products

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MnO4- Promoted Reactions
Kötz, A.
Steche, T. J. Prakt. Chem. 2, 1924, 107, 193.
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MnO4- Promoted Reactions
Requires stoichiometric amounts of KMnO4 (usually
2eq.) ? low yields because of over-oxidation
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Mechanism
Baldwin, J. E. Crossley, M. J.
Lehtonen, E.-M. M. J. Chem. Soc., Chem. Commun.,
1979, 918.
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MechanismSharpless Type Intermediates
Sharpless, K. B. Teranishi, A. Y.
Bäckvall, J.-E. J. Am. Chem. Soc. 1977, 99,
3120. Walba, D.
M. Wand, M. D. Wilkes, M. C. J. Am. Chem. Soc.
1979, 101, 4396.
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Asymmetric Induction with Chiral Auxiliaries
Walba, Przybyla, Walker JACS, 1990,
112, 5634.
Cecil, Hu, Vicent, Duncan, Brown JOC, 2004, 69,
3368.
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RuO4-Catalysed Reactions
Piccialli, Cavallo Tetrahedron Lett. 2001, 42,
4695.
Carlsen, P. H. J. Katsuli,
T. Martin, V. S. Sharpless K. B. J. Org. Chem.
1981, 46, 3936.
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Catalytic OsO4
Donohoe, T. J. Butterworth S.
Angew. Chem. Int. Ed. 2003, 42, 948.
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Catalytic OsO4
Donohoe, T. J. Butterworth S.
Angew. Chem. Int. Ed. 2003, 42, 948.
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Chiral Phase-Transfer Catalysis
Brown, C. D. Keily, J.
F. Angew. Chem. Int. Ed. 2001, 40, 4496. See
also Bhunnoo, R. A. Hu, Y. Lainé, D. I.
Brown, R. C. D. Angew. Chem. Int. Ed. 2002, 41,
3479.
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Conclusion

• Oxidative Cyclization of 1,5-Dienes
• provides a powerfull approach to the synthesis
  of targets containing cis-substituted THF rings.
• leads to the stereospecific formation of up to
  four new stereocenters and the THF ring
• provides a route to enantiomerically enriched
  THF products either through the use of
• chiral auxiliaries
• chiral phase-transfer catalyst