A New Approach in Enantioselective Catalytic with Bis(oxazoline) Ligand-Metal Complexes

In recent years, the research of enantioselective-catalyzed reaction and the catalyst has got great development. Of the various chiral catalysts, great attention was given to the C₂-symmetry chiral bis(oxazoline)ligand-metal complexes for they could be easily synthesized and have shown good enantioselection in various catalytic processes, including cyclopropanation from dihalogenmethane^[1] and diazoacetate^[2].But no report has been found of enantioselective-catalyzed cyclopropanation from sulfonyl-carbanions and alkenes. The test of chiral cyclopropanation from sulfonylcarbanions with nickel bis(oxazolinyl)pyridine catalyst has been made in our lab, and alkylation of aldehydes with diethyl zinc in the presence of nickel or iron bis(oxazolinyl)pyridine was also tested (scheme 1). Some asymmetric effects were observed in these reactions.