Approach to the Synthesis of Dimeric Salen-Co(Ⅲ):A Recoverable Catalyst for Rac-Eprichlorohydrin HKR

摘要

The synthesis of chiral dimeric Salen ligand 5,5'-methylene-di-[(R,R)-{N-(3-tert-butylsalicylidine)-N'-(3',5'-di-tert-butylsalicylidene)}-1,2-cyclohexanediamine] which using 2-tert-butylphenol as starting material is reported.This compound reacts with cobalt(Ⅱ) acetate and then oxidized by air to give dimeric Salen catalyst 5 in this paper,which catalyzes the hydrolytic kinetic resolution(HKR) of racemic epichlorohydrin to afford biologically important chiral epoxides and diols.Ee values of diol up to 97% were obtained,and the catalyst was recovered with no apparent loss.