Proton-abstraction mechanism in the palladium-catalyzed intramolecular arylation: substituent effects.
The regioselectivity observed in the intramolecular palladium-catalyzed arylation of substituted bromobenzyldiarylmethanes as well as theoretical results demonstrate that the Pd-catalyzed arylation proceeds by a mechanism involving a proton abstraction by the carbonate, or a related basic ligand. The reaction is facilitated by electron-withdrawing substituents on the aromatic ring, which is inconsistent with an electrophilic aromatic-substitution mechanism. The more important directing effect is exerted by electron-withdrawing substituents ortho to the reacting site.
García-Cuadrado
Domingo
D
Institute of Chemical Research of Catalonia, Av. Països Catalans 16, 43007 Tarragona, Spain.
de Mendoza
Paula
P
Braga
Ataualpa A C
AA
Maseras
Feliu
F
Echavarren
Antonio M
AM