Oxidative Addition of Haloheteroarenes to Palladium(0): Concerted versus S N Ar-Type Mechanism

Bert U.W. Maes (1) , Stefan Verbeeck (1) , Tom Verhelst (1) , Audrey Ekomié (2) , Niklas Von wolff (2) , Guillaume Lefèvre (3) , Emily A. Mitchell (1) , Anny Jutand (2)

1 department of chemistry
2 PASTEUR - Processus d'Activation Sélective par Transfert d'Energie Uni-électronique ou Radiatif (UMR 8640)
3 LCMCE - Laboratoire de Chimie Moléculaire et de Catalyse pour l'Energie (ex LCCEF)

The kinetics of the oxidative additions of haloheteroarenes HetX (X=I, Br, Cl) to [Pd-0(PPh3)(2)] (generated from [Pd-0(PPh3)(4)]) have been investigated in THF and DMF and the rate constants have been determined. In contrast to the generally accepted concerted mechanism, Hammett plots obtained for substituted 2-halopyridines and solvent effects reveal a reaction mechanism dependent on the halide X of HetX: an unprecedented SNAr-type mechanism for X=Br or Cl and a classical concerted mechanism for X=I. These results are supported by DFT studies.

Domains: Material chemistry

Bert U.W. Maes, Stefan Verbeeck, Tom Verhelst, Audrey Ekomié, Niklas Von wolff, et al.. Oxidative Addition of Haloheteroarenes to Palladium(0): Concerted versus S N Ar-Type Mechanism. Chemistry - A European Journal, 2015, 21 (21), pp.7858 - 7865. ⟨10.1002/chem.201406210⟩. ⟨cea-01635498⟩