摘要
A highly efficient asymmetric(3 + 2) cycloaddition of α-diazo pyrazoleamides with silyl enol ethers was realized by employing a chiral N,N’-dioxide-Ni(II) complex catalyst. The process includes the formation of chiral nickel carbenoid intermediate and the following enantioselective cycloaddition reaction. The desired dihydrofuran O,O-acetal derivatives were obtained in good yields(up to 90%) with high enantioselectivity(up to 99% ee) under mild reaction conditions within short reaction time. On the basis of the determination of the catalyst structure, a possible transition state mode was proposed.
基金
the National Natural Science Foundation of China(No. 22188101)
Sichuan Science and Technology Program (No.2021YJ0561)
Sichuan University (No. 2020SCUNL204)for financial support。