β‐Functionalization of 4 a‐aza‐8 a‐boranaphthalene via Iridium‐catalyzed C−H Borylation

Abstract A general method for the functionalization of 4a ‐ aza‐8a ‐ boranaphthalene in the position β to the nitrogen atom has been developed. This method is based on a regioselective iridium‐catalyzed C−H activation process for the introduction of a boronate group, which can subsequently be transformed into a variety of aryl or alkynyl groups via cross‐coupling reactions. Selective mono‐ or difunctionalization can be achieved by controlling the reaction conditions during the borylation step. The photophysical properties of the obtained 3‐ or 3,6‐substituted BN‐naphthalenes have been evaluated, and some of them have been found to be significantly fluorescent, with fluorescence quantum yields up to 0.85.