Abstract: Dichoropyridazine was reacted with quinidyl and dihydroquinidyl in the presence of NaH in DMF to give compound 2. The side of quinidyl was reacted with 2-mercaptoethanol, then was oxidized to give ligand 1. Ligand 1 delivers excellent enantioselectivity as well as specific chemoselectivity in the asymmetric dihydroxylation(AD) of six olefins(88%—99% e.e). and 74%—91% isolated yields were obtained in AD reaction. Furthermore this ligand can be recovered and reused. Its enantioselectivity and chemoselectivity were unchangeable when it was reused for four times in AD reaction with cinnamic ethyl as the substrate.

Key words: Recoverable ligand, Asymmetric dihydroxylation, Chiral vicinal diol