HBF4‐Catalyzed 3,6‐Bis‐diarylmethylation of Carbazoles with para‐Quinone Methides

In this article, we demonstrate an atom economical, practical, mild and selective HBF4‐catalyzed 1,6‐conjugate addition of carbazoles to para‐Quinone Methides (p‐QMs) to access 3,6‐bis‐diarylmethyl‐ and mono‐diarylmethyl carbazoles. This metal and additive free protocol provides convenient access to the substituted carbazole derivatives in moderate to excellent yields with a good functional group tolerance. It was found that a couple of 3,6‐disubstituted carbazoles showed interesting photophysical properties and, therefore, might potentially find some applications as host materials in OLEDs. An atom‐economical, selective and a general acid‐catalyzed method has been developed to access mono‐ and bis‐diarylmethylated carbazole derivatives under mild conditions. This transformation proceeds through a selective 1,6‐conjugate addition of carbazoles to p‐quinone methides. The photophysical studies on some of the 3,6‐bis‐diarylated carbazoles revealed that these molecules exhibit fluorescence properties and thus, could be used in OLEDs.