Aminoboration: Addition of B–N σ Bonds across C–C π Bonds

This communication demonstrates the first catalytic aminoboration of C-C π bonds by B-N σ bonds and its application to the synthesis of 3-borylated indoles. The regiochemistry and broad functional group compatibility of this addition reaction enable substitution patterns that are incompatible with major competing technologies. This aminoboration reaction effects the formation of C-B and C-N bonds in a single step from aminoboronic esters, which are simple starting materials available on the gram scale. This reaction generates synthetically valuable N-heterocyclic organoboron compounds as potential building blocks for drug discovery. The working mechanistic hypothesis involves a bifunctional Lewis acid/base catalysis strategy involving the combination of a carbophilic gold cation and a trifluoroacetate anion that activate the C-C π bond and the B-N σ bond simultaneously.