Direct C–H electrophilic borylation with (C6F5)2B–NTf2 to generate B–N dibenzo[a,h]pyrenes

Abstract

The borylation of aryl substituted pyridines is an effective way of preparing B–N doped conjugated organic frameworks. Trihaloborane Lewis acids are often employed for this protocol, and may require further functionalization to replace the remaining halides on boron. We report a new, fully characterized, electrophilic borylating agent, (C₆F₅)₂B(κ²-NTf₂), that smoothly incorporates a –B(C₆F₅)₂ unit into the model substrate 2-phenylpyridine. To demonstrate its utility in preparing more complex B–N doped structures, we use it to prepare seven examples of the 6a,13a-diaza-7,14-dibora-dibenzo[a,h]pyrene framework, with substituents of varying donor properties. The structural, redox, and photophysical properties of this new family of B–N doped polycyclic hydrocarbon compounds were probed experimentally and computationally.