Rh-Catalyzed Carboxylation of Boronic Esters with CO₂

Significance

While many reports on the Rh-catalyzed reaction of aryl- and alkenylboronates with various electrophiles have been published, no direct carboxylation of such compounds was known so far. A large amount of arylboronic acids is commercially available, and alkenyl boronates can be easily prepared in situ from terminal acetylenes. A simple transformation of these compounds into the corresponding carboxylic acids will be a useful synthetic tool.