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.