Photoredox Oxo-C(sp3)-H Bond Functionalization via in Situ Cu(I)-Acetylide Catalysis.

A unified strategy for the synthesis of 2-vinyl heterocycles is reported. With visible light irradiation, simple and cheap CuCl is able to functionalize a terminal alkyne, giving Cu(I)-acetylide in situ. Unlike the case of noble metals or organic dye photocatalysts, this critical Cu(I)-acetylide not only activates the C-H bond of terminal alkynes but also serves as a photocatalyst to achieve varieties of 2-vinyl heterocycles in good to excellent yields, even for large scale and late-stage functionalization of natural product.