Herein we report a novel N-directed electrophilic C-H borylation method proceeding by protonation of the amino-borane to form borenium (three coordinate at boron) cations. This enables access to challenging to synthesise azaborine containing PAHs even at room temperature, including [5]-and [6]helicenes containing BN units in the helical backbone. These BN-helicenes have improved photophysical properties relative to the [5]-and carbo [6]helicenes, further highlighting the beneficial effects afforded by BN incorporation into helicenes.