Application of well-defined chain-end-functionalized polystyrenes with dendritic chiral ephedrine moieties as reagents for highly catalytic enantioselective addition of dialkylzincs to aldehydes

Using Soluble Polymer Supports To Facilitate Homogeneous Catalysis

“…135,136 In these reports, recycling was not emphasized. Recycled catalysts were as effective as the starting catalyst, but only one recycle was described in either reaction 85 or 86.…”

“…These include dendrimers containing carbosilane backbones like 78 that have a corona of chiral ephedrine moieties − and polystyrene terminated with dendritic chiral ephedrine moieties ( 79 ). , In these reports, recycling was not emphasized. Recycled catalysts were as effective as the starting catalyst, but only one recycle was described in either reaction 85 or 86.…”

Recyclable Stereoselective Catalysts

“…The authors prepared a chiral dendrimer bearing ephedrine ligands on the periphery and a styrene moiety in the core that was polymerized to form a linear and soluble polystyrene chain. This macromolecule, 279 , could be precipitated and reused without considerable efficiency erosion …”

“…This macromolecule, 279, could be precipitated and reused without considerable efficiency erosion. 520 Sasai et al prepared micellar nanoparticles via polymerization of amphiphilic units containing a styrene moiety in water. The asymmetric ligand BINOL derivative prepared could be grafted before or after polymerization.…”

Recyclable Stereoselective Catalysts

“…1.47 ) showed an impressive recycling ability, since it was reused nine times without any signifi cant decrease of reactivity and enantioselectivity [209] . Heterogeneous supports furnished a more robust catalyst than those prepared for homogeneous catalysis, in which soluble polystyrene polymers [210] and dentritic [211,212] structures were examined as supports. However, when dealing with homogeneous catalysis it is crucial to highlight the work of Kim et al In this work was described a method for the modifi cation of pyrrolidinylmethanol derivatives to be applied in asymmetric addition of diethyl zinc to aldehydes [213] .…”