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

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