Catalytic methoxylation of aryl halides using ¹³C- and ¹⁴C-labeled CO₂

The functionalization of carbon dioxide (CO₂) into high-value building blocks is a relevant topic in carbon isotope labeling, where CO₂ is the primary carbon source. A catalytic methoxylation of aryl halides directly from [¹³C] and [¹⁴C]CO₂ is reported. Relying on the intermediacy of the methoxyborane BBN-OCH₃, as a new secondary nucleophilic labeled source, this strategy allowed labeling of a series of substrates, including challenging pharmaceuticals containing tertiary alkyl amine substituents.