Ligand-free iridium-catalyzed regioselective C–H borylation of indoles

We herein report a ligand-free Ir-catalyzed C–H borylation of N-acyl protected indoles. This simple protocol could tolerate a variety of functional groups, affording C3 borylated indoles in good yields with excellent regioselectivities. We also demonstrated that the current method is amenable to gram-scale borylation and the C–B bonds could be easily converted to C–C and C-heteroatom bonds.