What is rotaxane?

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
Structure of Rotaxane
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  -exonuclease.
Thordarson, P.; Bijsterveld, E. J. A.; Rowan, A. E.; Nolte, R. J. M. Nature 2003, 424, 915.
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
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.
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
Through-space
Chirality Transfer
•Concentlation of catalyst
•The length of the axle component
•Substituents on benzaldehydes
•Using DMSO as solvent
•Temperature effect
Synthesis of Rotaxane 10
Asymmetric Benzoin condensation
catalyzed by 7, 10, 11
Through-bond Chirality Transfer
Influence of existance of ring component
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.

Download Report