Mechanistic considerations and the choice of catalyst

In 1991 Farina carried out a detailed study on the effect of ligands on the reaction between vinyltributyltin and several halides and triflates [77], His conclusion was that the best ligand for this type of reaction was tris(2-furyl)phosphine. Halides (particularly iodides) and triflates are indeed the most frequently used leaving groups, although Roth and Sapino showed that fluorosulfonates can also be used [78] their catalyst was palladium(II) acetate. A look at the catalyst (or to be exact precatalyst) and cocatalyst combinations, together with solvent variations, which have been used in the papers cited above will make it clear that there is in fact no ideal system, but that each reaction will basically require optimization. 

This is made particularly clear by the result (Section 4.2.2) obtained by Pattenden, [46] who needed to use two different catalysts to close the same size of ring because of the presence of different functionalities. 

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