Nickel/Zinc Iodide Co-catalytic Asymmetric [2+2] Cycloaddition Reactions of Azabenzonorbornadienes with Terminal Alkynes

The asymmetric [2+2] cycloaddition reactions of alkenes with alkynes are interesting as it has provided a powerful method for the construction of fused and strained cyclobutenes with multiple chiral centers. In this paper, we report the establishment of a dual catalysts system comprising nickel and zinc, which allowed the asymmetric [2+ 2] cycloaddition reactions of azabenzonorbornadienes with terminal alkynes in good yields and excellent enantioselectivities.