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, Takata T. et al. J.Am.Chem.Soc. 2004, 126, Tobe Laboratory Hirokazu TAKANO

Structure of Rotaxane

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

Benzoin Condensation The cyanide ion-catalyzed

Benzoin Condensation Catalyst

Binaphthol-Based Chiral Crown Ether source of chiral environment

Synthesis of Pseudorotaxane Functionalized Chirality

The Face Selective Hydrogen Abstraction of 5 from 3

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. Summary 1

Design of Rotaxane Catalysts Through -Space Through-Bond

Synthesis of Rotaxane 7a

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

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

Synthesis of Rotaxane 10

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

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.