Polymer-supported BINOL ligand for the titanium-catalyzed diethylzinc addition to aldehydes: A remarkable positive influence of the support on the enantioselectivity of the catalyst

A new polymer-supported BINOL (1,1'-Bi-2-naphthol) :was synthesized by coupling of aminomethyl polystyrene resin and (S)-2,2'-dihydroxy-1,1'-binaphthyl-3,3'-dicarboxylic acid. This new ligand was found to be more enantioselective for the asymmetric addition of diethylzinc to aldehydes than its free analog [Ti(BINOL)(PrO2)-Pr-i]. A range of 57-99% ee's as well as 78-97% yields was obtained, and: the electronic properties of the enantioselectivity were also observed.