Palladium-Catalyzed Suzuki-Miyaura Reactions with Triazenyl-Tethered Aryl Bromides: Exploiting the Orthogonal Coupling Sites under Different Conditions.

Transition-metal-catalyzed cross-coupling of arenes bearing two or more potential coupling sites is often challenging because of the chemoselectivity issue. If orthogonal cross-couplings were applicable, one can develop a synthetically useful approach for consecutive functionalization of the starting arenes compounds. We herein reported a Suzuki-Miyaura coupling of triazenyl-substituted aryl bromides catalyzed by PdCl 2 (PCy 3 ) 2 /PPh 3 under basic conditions. The resultant polyfunctionalized aryl triazenes could undergo Suzuki-Miyaura couplings under acidic conditions or be converted to many other functionalized arenes. This orthogonal coupling strategy allows for a sequential functionalization of arenes with same type of nucleophilic reagents toward the synthesis of diverse biaryls and teraryls.