Copper-Catalyzed Enantioselective Formal [4 + 1] and [3 + 3] Cycloaddition of Ethynylethylene Carbonates.

Herein we employed ethynylethylene carbonates (EECs) to achieve formal [4 + 1] and [3 + 3] cycloaddition with cyclic 1,3-dicarbonyl compounds. On one hand, EECs with styryl substitution could undergo a remotely controlled enantioselective [4 + 1] cycloaddition reaction. This reaction exhibits good chemoselectivity, regioselectivity, and enantioselectivity. In addition, a [3 + 3] cycloaddition reaction of EECs with cyclic 1,3-dicarbonyl compounds was also achieved, leading to a series of 4H-pyrans with impressive chemoselectivity and enantioselectivity.