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Asymmetric Benzoin Condensation Catalyzed

Asymmetric Benzoin Condensation Catalyzed by Chiral Rotaxanes Tethering a Thiazolium Salt Moiety via the Cooperation of the Component. Reference. Takata T. et al. Chem.Lett. 2000 , 806-807 Takata T. et al. J.Am.Chem.Soc. 2004 , 126 , 3438-3439. Tobe Laboratory Hirokazu TAKANO.

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Asymmetric Benzoin Condensation Catalyzed

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  1. Asymmetric Benzoin Condensation Catalyzed by Chiral Rotaxanes Tethering a Thiazolium Salt Moiety via the Cooperation of the Component Reference Takata T. et al. Chem.Lett.2000, 806-807 Takata T. et al. J.Am.Chem.Soc.2004, 126, 3438-3439 Tobe Laboratory Hirokazu TAKANO

  2. Structure of Rotaxane

  3. Example of Rowan’s Rotaxane Catalyst the epoxidation of the axle by using the wheel component as catalyst. the first intramolecular rotaxane catalyst mimicking the DNA enzyme λ-exonuclease. Thordarson, P.; Bijsterveld, E. J. A.; Rowan, A. E.; Nolte, R. J. M. Nature 2003, 424, 915.

  4. Benzoin Condensation The cyanide ion-catalyzed

  5. Benzoin Condensation Catalyst

  6. Binaphthol-Based Chiral Crown Ether source of chiral environment

  7. Synthesis of Pseudorotaxane Functionalized Chirality

  8. The Face Selective Hydrogen Abstraction of 5 from 3

  9. Summary 1 Rotaxane based on binaphthol-based crown ether 1 provides an effective chiral environment. Althrough the degree of chirality introduction is not high, this is the first example of asymmetric induction on rotaxane.

  10. Design of Rotaxane Catalysts Through -Space Through-Bond

  11. Synthesis of Rotaxane 7a

  12. Benzoin Condensation Catalized by Chiral Rotaxane ee = enantiomer excess (エナンチオマー過剰率)

  13. Asymmetric Benzoin condensation catalyzed by 7 • Concentlation of catalyst • The length of the axle component • Substituents on benzaldehydes • Using DMSO as solvent • Temperature effect Through-space Chirality Transfer

  14. Synthesis of Rotaxane 10

  15. Asymmetric Benzoin condensation catalyzed by 7, 10, 11 Through-bond Chirality Transfer Influence of existance of ring component

  16. Summary 2 The authors’ first attempt to demonstrate the catalysis of rotaxanes may help clarify the fundamental features of rotaxane structure which was shown to give a unique reaction field in asymmetric benzoin condensation. A more precise design for the asymmetric rotaxane catalyst based on the guiding principle obtained here will result in rotaxanes with higher chemical and asymmetric yields.

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