A Pd-catalyzed, boron ester-mediated, reductive cross-coupling of two aryl halides to synthesize tricyclic biaryls.

Tricyclic biaryls are important scaffold structures in many natural products and lead compounds in drug discovery. The formation of a biaryl unit is often the key step for the synthesis of tricyclic biaryls. Despite significant progress toward the synthesis of biaryl compounds in recent years, the direct cross-coupling of two different aryl halides is still challenging and robust methods are lacking. Herein we report a direct cross-coupling of two different aryl halides in the presence of a palladium catalyst and boron ester, which provides a new and useful complementary method to synthesize tricyclic biaryls.