Exploiting the trifluoroethyl group as a precatalyst ligand in nickel-catalyzed Suzuki-type alkylations

We report herein the exploitment of the partially fluorinated trifluoroethyl as precatalyst ligands in nickel-catalyzed Suzuki-type alkylation and fluoroalkylation coupling reactions. Compared with the [L n Ni II (aryl)(X)] precatalysts, the unique characters of bis-trifluoroethyl ligands imparted precatalyst [(bipy)Ni(CH 2 CF 3 ) 2 ] with bench-top stability, good solubilities in organic media and interesting catalytic activities. Preliminary mechanistic studies reveal that an eliminative extrusion of a vinylidene difluoride (VDF, CH 2 &z.dbd;CF 2 ) mask from [(bipy)Ni(CH 2 CF 3 ) 2 ] is a critical step for the initiation of a catalytic reaction. A bis-trifluoroethyl coordinated nickel/bipyridine complex has been developed as efficient precatalyst for diverse Suzuki-type alkylations which features unconventional precatalyst initiation mode.