Design of Catalyst System for Enantioselective Borohydride Reduction with Environmental Benign

点击翻译按钮获取中文摘要

The key reactive intermediate of borohydride reduction catalyzed by Schiff base-cobalt complexes is proposed to be the dichloromethyl-cobalt hydride with a sodium cation, based on experimental and theoretical studies. It was revealed that chloroform is not the solvent but the reactant that activates the cobalt catalyst. It was found that a catalytic amount of chloroform effectively activated the present catalytic system to convert various ketones into the corresponding reduced product with a high ee in the THF solvent. Furthermore, the theoretical simulation of various axial groups in cobalt complex catalysts predicted that the cobalt-carbene complexes could be employed as efficient catalysts. The newly designed complexes generated from cobalt complex and methyl diazoacetate made it possible to catalyze the enantioselective borohydride reduction in a halogen-free solvent.