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.

近年来，通过C-H官能化对胺类化合物的修饰研究已成为一个重要的研究领域，但通常依赖于引入导向基团或立体阻碍胺类方法。鉴于游离胺导向的C(sp3)-H活化在主要限于环化反应，为了提升基于胺类的C-H活化在可持续性和反应范围上的表现，我们提出了一种利用干冰形态的二氧化碳促进分子间C-H芳基化的策略。该方法已被应用于实现一种操作简便的程序，其中一级和二级脂肪族胺能够在其γ-C-H位置上进行选择性芳基化。除了可能作为导向基团的作用外，二氧化碳还被证实可以减少对敏感胺类底物的氧化。