Monophosphine pathway reaction

Thus, the reductive eliminations from tranx-bis(triphenylphosphine) amido-aryl complexes 86 showed first-order kinetics demonstrating that the reductive elimination takes place from monomeric species (Scheme 1.54). The dependence of the reaction rate on the concentration of added PPhj is compatible with two competing mechanisms, one involving C-N bond formation to a ds-16-electron species 87 formed by isomerization of the trans derivative. The other mechanism involves initial reversible phosphine dissociation to give a 14-electron threebond formation (Scheme 1.54). Dimeric monophosphine complexes follow a dissociative pathway to give threereductive elimination. The formation of the 14-electron intermediates can be reversible or irreversible depending on the type of amine. 

When a carboxylate or ketone-substituted alkyne was used for the hydrophosphination reaction, the corresponding monophosphine-substituted intermediate exists as a classical enol-keto equilibrium mixture, which is sensitive to the pH of the reaction. Therefore, by regulating the amount of triethylamine as a noncoordinating external base, the (1,1)- and (1,2)-addition pathways could be... 

As far as the bromoarenes are concerned, the oxidative addition to Pd complexes containing the ligands L = l-AdP(t-Bu)2 and L = CyP(t-Bu)2 appeared to occur by two competitive paths involving rate-determining reactions of bisphosphine complexes to give rise to monophosphine intermediates (i.e. pathway B and pathway C). Besides, the oxidative addition to Pd complexes with the hgand... 

---