Carbon Dioxide-Mediated C(sp³)–H Arylation of Amine Substrates

Elaborating amines via C–H functionalization has been an important area of research over the past decade but has generally relied on an added directing group or sterically hindered amine approach. Since free-amine-directed C­(sp³)–H activation is still primarily limited to cyclization reactions and to improve the sustainability and reaction scope of amine-based C–H activation, we present a strategy using CO₂ in the form of dry ice that facilitates intermolecular C–H arylation. This methodology has been used to enable an operationally simple procedure whereby 1° and 2° aliphatic amines can be arylated selectively at their γ-C–H positions. In addition to potentially serving as a directing group, CO₂ has also been demonstrated to curtail the oxidation of sensitive amine substrates.