Catalytic Enantioselective Alkylation Using New Chiral Schiff Base as Tridentate Ligand

摘要

There have been many reports on enantioselective addition of dialkylzinc to aldehydes. Most of them are catalyzed by bidentate beta-amino alcohol or their derivatives. To our knowledge, there are only three reports using tridentate ligands; furthermore, all of them afforded the alkylated products in lower enantiomeric excess (ee) than excellent beta-amino alcohol system. For example, Corey and Hannon reported enantioselective ethylation of benzaldehyde catalyzed by a tridentate ligand derived from (+)-pseudoephedrine to give 1-phenyl-1-propanol in 87% ee.