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)(i)PrO(2)]. 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.
Yang
XW
Union Laboratory of Asymmetric Synthesis and School of Life Science, Lanzhou University, Lanzhou 730000, China, and Union Laboratory of Asymmetric Synthesis and Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic Universi.
Sheng
JH
Da
CS
Wang
HS
Su
W
Wang
R
Chan
AS