Photoexcited Ni II -Aryl Complex-Mediated Giese Reaction of Aryl Bromides.

A Giese reaction of aryl bromides with electron-deficient alkenes was developed, enabled by a dual catalyst system containing Ni ^II complex and Ir ^III photocatalyst. This protocol could accommodate a variety of aryl bromides and electron-deficient alkenes, delivering the conjugate adducts in up to 97% yield. The utilization of photoexcited (dtbbpy)Ni ^II (aryl)Br intermediate as an aryl radical source allows this novel transformation of aryl halides, thus expanding the chemical space of excited nickel catalysis.