Mechanism of the Stille Reaction Catalyzed by Palladium Ligated to Arsine Ligand: PhPdI(AsPh3)(DMF) Is the Species Reacting with Vinylstannane in DMF

Publisher Website
Google Scholar
Abstract
The kinetics of the reaction of PhPdI(AsPh3)2 (formed via the fast oxidative addition of PhI with Pd0(AsPh3)2) with a vinyl stannane CH2 CH−Sn(n-Bu)3 has been investigated in DMF. This reaction (usually called transmetalation step) is the prototype of the rate determining second step of the catalytic cycle of Stille reactions. It is established here that the transmetalation proceeds through PhPdI(AsPh3)(DMF), generated by the dissociation of one ligand AsPh3 from PhPdI(AsPh3)2. PhPdI(AsPh3)(DMF) is the reactive species, which leads to styrene through its reaction with CH2 CH−SnBu3. Consequently, in DMF, the overall nucleophilic attack mainly proceeds via a mechanism involving PhPdI(AsPh3)(DMF) as the central reactive complex and not PhPdI(AsPh3)2. The dimer [Ph2Pd2(μ2-I)2(AsPh3)2] has been independently synthesized and characterized by its X-ray structure. In DMF, this dimer dissociates quantitatively into PhPdI(AsPh3)(DMF), which reacts with CH2 CH−SnBu3. The rate constant for the reaction of PhPdI(AsPh3)(DMF) with CH2 CH−SnBu3 has been determined in DMF for each situation and was found to be comparable.

This publication has 11 references indexed in Scilit: