Formal Ir-Catalyzed Ligand-Enabled Ortho and Meta Borylation of Aromatic Aldehydes via in Situ-Generated Imines.

The ligand-enabled development of ortho and meta C-H borylation of aromatic aldehydes is reported. It was envisaged that while ortho borylation could be achieved using tert-butylamine as the traceless protecting/directing group, meta borylation proceeds via an electrostatic interaction and a secondary interaction between the ligand of the catalyst and the substrate. These ligand-substrate electrostatic interactions and secondary B-N interactions provide an unprecedented controlling factor for meta-selective C-H activation/borylation.