Three roles for the fluoride ion in palladium-catalyzed Hiyama reactions: transmetalation of [ArPdFL₂] by Ar'Si(OR)₃

Christian Amatore; Laurence Grimaud; Gaëtan Le Duc; Anny Jutand

doi:10.1002/anie.201400956

Three roles for the fluoride ion in palladium-catalyzed Hiyama reactions: transmetalation of [ArPdFL₂] by Ar'Si(OR)₃

Angew Chem Int Ed Engl. 2014 Jul 1;53(27):6982-5. doi: 10.1002/anie.201400956. Epub 2014 May 23.

Authors

Christian Amatore¹, Laurence Grimaud, Gaëtan Le Duc, Anny Jutand

Affiliation

¹ Ecole Normale Supérieure-PSL Research University, Département de Chimie, Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 8640 PASTEUR, 24 Rue Lhomond, 75231 Paris Cedex 5 (France). christian.amatore@ens.fr.

PMID: 24861669
DOI: 10.1002/anie.201400956

Abstract

From the kinetic data on the transmetalation/reductive elimination in fluoride-promoted Hiyama reactions, obtained using electrochemical techniques, it has been established that fluoride ions play three roles. F(-) reacts with trans-[ArPdBrL2] (L=PPh3) to form trans-[ArPdFL2], which reacts with Ar'Si(OMe)3 in the rate-determining transmetalation, whereas trans-[ArPdBrL2] does not react with Ar'Si(OMe)3. F(-) reacts with Ar'Si(OMe)3 to deliver the unreactive silicate Ar'SiF(OMe)3(-), thus leading to two antagonistic kinetic effects. In addition, F(-) catalyzes the reductive elimination from intermediate trans-[ArPdAr'L2].

Keywords: cross-coupling; fluoride; kinetics; palladium; reaction mechanisms.