Solvent effect on palladium-catalyzed cross-coupling reactions and implications on the active catalytic species.

Suzuki coupling of the bifunctional substrate 1 using [Pd(2)(dba)(3)]/PtBu(3) gives selectivity for C-Cl in nonpolar solvents but for C-OTf in polar solvents. The results of computational and experimental studies suggest that the catalytically active species in polar solvents under conditions employing coordinating additives is inconsistent with monoligated [Pd(PtBu(3))]. Instead, the data are consistent with an anionic palladium complex as the active species.