Isodesmic C-H Borylation: Perspectives and Proof of Concept of Transfer Borylation Catalysis

The potential advantages of using arylboronic acids<br>or esters as boron source in the C-H borylation are discussed. The<br>concept is showcased by using commercially available and air-stable<br>2-mercaptopyridine as a metal-free catalyst for the transfer<br>borylation of heteroarenes, using furylboronic acid catechol ester<br>as the borylation agent. The catalysis can be performed in air using<br>unpurified solvent and shows a unique functional group tolerance<br>among C-H borylation reactions, tolerating notably alkene and alkyne<br>functional groups. The computational investigation of the<br>mechanism is also described.<br>