Hydrobenzoin derived novel chiral ligands and their application

In this work, novel chiral ligands as bromo- and phenyl-substituted hydrobenzoin derivatives have been synthesized in a straight forward manner with good yields. The synthesized enantiomerically pure (1R,2R)-1,2-bis- (3'-bromophenyl)-ethane-1,2-diol (4) and (1R,2R) -1,2-bis- (3'-phenylphenyl)-ethane-1,2-diol (5) were characterized by using 1H- NMR, 13C-NMR, IR and mass spectral data. These synthesized chiral ligands (4) and (5) have been evaluated in the enantioselective addition of diethylzinc to aromatic and aliphatic aldehydes. Moderate results were obtained in the ethylation of 2-methoxybenzaldehyde under the catalysis of (4) (%63 ee) and (5) (%70 ee). All ligands were performed in addition reaction of diethylzinc to aldehydes in the presence of Ti(iOPr)4 and it was observed that in general catalytic activities were increased.