Application of the Suzuki–Miyaura Reaction for the Postfunctionalization of the Benzo[4,5]thiazolo[3,2‑c][1,3,5,2]oxadiazaborinine Core: An Approach toward Fluorescent Dyes

A fluorescent dye based on the 8-brominated benzo­[4,5]­thiazolo­[3,2-c]­[1,3,5,2]­oxadiazaborinine core was synthesized from benzo­[d]­thiazol-2-amine. The new boron complex can be effectively modified by a palladium-catalyzed Suzuki–Miyaura cross-coupling reaction with (het)­arylboronic acids. This reaction allows a valuable regioselective postfunctionalization of 1,3,5,2-oxadiazaborinine chromophores with different aromatic substituents. The solutions of obtained target complexes in organic solvents demonstrate high fluorescence quantum yields. The compound with a 4-cyanophenyl group at benzothiazole unit (Ar = 4-C₆H₄CN) exhibits a comparatively high fluorescence quantum yield of 0.31 in the solid state.