Although carbon dioxide (CO₂) is an attractive renewable carbon source, its utilization to produce fine chemicals through the catalytic carboxylation of unactivated carbon–hydrogen (C–H) bonds is still very limited and remains a challenge, largely because CO₂ is thermodynamically and kinetically stable. In particular, the generation of (hetero)aromatic carboxylic acids via a transition-metal-catalysed C–H carboxylation of arenes with CO₂ is extremely rare. Here we report a ligand-enabled site-selective carboxylation of 2-arylphenols under atmospheric pressure of CO₂ through a Rh₂(OAc)₄-catalysed and chelation-assisted C–H bond activation. Remarkably, the reaction occurs selectively on the less nucleophilic phenyl group with the promotion of a phosphine ligand, which overrides the site selectivity dictated by the well-known Kolbe–Schmitt type reaction. The non-acidic C–H bonds within several important classes of heterocycles were also efficiently carboxylated with this method. A mechanistic investigation revealed complexes of active catalysts and that this reaction proceeds under redox-neutral reaction conditions.

尽管二氧化碳（CO ₂）是一种有吸引力的可再生碳源，但其通过未活化的碳氢键（C–H）的催化羧化来生产精细化学品的应用仍然非常有限，并且仍然是一个挑战，主要是因为CO ₂具有热力学性质并且动力学稳定。特别是，通过过渡金属催化的芳烃与CO _2的C–H羧化反应生成（杂）芳族羧酸的情况极为罕见。在这里，我们报告了在大气压下，通过Rh ₂（OAc）₄在CO ₂大气压下2-芳基酚的配位体能位选择性羧化催化和螯合辅助的CH键活化。值得注意的是，该反应选择性地在亲核性较低的苯基上发生，并带有膦配体，这超出了众所周知的Kolbe-Schmitt型反应所决定的位点选择性。该方法还可以有效地将几个重要类别的杂环中的非酸性C–H键羧基化。机理研究揭示了活性催化剂的配合物，并且该反应在氧化还原中性反应条件下进行。