Triazene as the Directing Group Achieving Highly Ortho -Selective Diborylation and Sequential Functionalization.

This study describes a regioselective ortho , ortho '-diborylation of aromatic triazenes catalyzed by [Ir(OMe)(cod)] 2 in near-quantitative yields without an additional ligand. Aromatic triazenes act as both substrates and ligands. The X-ray structures of 2a and 2p indicate that the monoborylation products could promote the occurrence of diborylation. The synthesized triazene-substituted diboronate esters could undergo a variety of transformations including directing group removal. One-pot sequential modification provides a short entry to densely functionalized arenes.