Phase transfer catalysts, chiral polymer based

Recently, Sirit and co-workers [45] developed calixarene-based chiral phase-transfer catalysts derived from cinchona alkaloids successfully used for alkylation of glycine-imine esters. In 2010, Itsuno et al. [46] published quartemary ammonium sulfonate polymers used for a-alkylation reaction of a glycine imine ester with high yields and enantioselectivity. 

In addition, in 2(X)4 Mamoka and co-workers [72] synthesized a recyclable fluorous chiral phase-transfer catalyst which was successfully applied for the catalytic asymmetric alkylation of a glycine-imine derivative followed by extractive recovery of the chiral phase-transfer catalyst using fluorous solvent. Later, in 2010 Itsuno and co-workers [73] published a new type of polymer-supported quarternary ammonium catalysts based on either cinchona alkaloids or Maruoka s-type catalyst bound via ionic bonds to the polymeric sulfonates. 

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