http://onlinelibrary.wiley.com/doi/10.1002/ejoc.201200838/abstract
Asymmetric Ion-Pairing Catalysis of the Reversible Cyclization of 2′-Hydroxychalcone to Flavanone: Asymmetric Catalysis of an Equilibrating Reaction
Lukas Hintermann and Claudia Dittmer
The cyclization of nonactivated 2′-hydroxychalcones to flavanones has been realized for the first time with asymmetric induction. In spite of the reversibility of the reactions, this ion-pairing catalysis reaches intrinsic enantioselectivities of up to S = 14.4 (er = 93.5:6.5) and illustrates the characteristic behavior of reversible asymmetric catalyses close to their equilibria.
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DR ANTHONY
