Atropisomeric polymer

Keywords Macromolecular stereochemistry. Main-chain chiral polymer, Atropisomeric polymer, Kinetic resolution. Anionic polymerization. Cationic polymerization. Insertion polymerization... 

Pu and co-workers incorporated atropisomeric binaphthols in polymer matrixes constituted of binaphthyl units, the macromolecular chiral ligands obtained being successfully used in numerous enantioselective metal-catalyzed reactions,97-99 such as asymmetric addition of dialkylzinc reagents to aldehydes.99 Recently, they also synthesized a stereoregular polymeric BINAP ligand by a Suzuki coupling of the (R)-BINAP oxide, followed by a reduction with trichlorosilane (Figure 10).100... 

Polyisocyanides have a rigid helical structure with four monomeric units per helix turn [254,255]. The polymers of isocyanides do not display any stereoisomerism, since the carbon atoms in the polymer backbone are not chirotropic. However, it is worth noting that isocyanide polymerisation is stereoselective as regards the screw sense of the polymeric helix (atropisomerism). Therefore, right- and left-handed helices are formed from achiral isocyanides [256], When the monomer is achiral, a racemic mixture of right- and left-handed helices is obtained, e.g. in the case of the polymerisation of t-butylisocyanide [257,258]. When the alkyl... 

New azobenzene-modified polyesters and PEAs fitted with chiral, atropisomeric binaphthylene segments (Figure 8.25) were prepared by a series of polycondensation reactions carried out in polar solvent media [99]. The simple incorporation of ester groups in the polymer backbone provided significant improvements in organosolubiUty behaviors. The choice of both solvent and tanperature allowed to modulate, over a relatively wide latitude, the pho-toregulated oscillations in optical rotatory power recorded for these new materials when stimulated with multiple... 

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