Silver in Pd-catalyzed couplings

Such processes are well known in palladium chemistry and quite important, because of the role of palladium-catalyzed C-C bond formation in organic chemistry.3 

In the latter reactions, at least one step corresponded to a carbometallation reaction. Such carbometallations also arose in Heck reactions, and indeed, several conditions set up for such Heck reactions relied on silver salts.49 In these reactions, silver salts only seemed to abstract halide from intermediate palladium species their role could, however, be more complex. 

These results led other investigators to propose that the Heck reaction proceeds via an ionic pathway or a neutral variant, depending on the starting materials and on the 

More recently, substituted allenyl sulfones were also engaged in Pd/Ag-catalyzed Heck-type reactions. Treated with palladium tetrakis(triphenylphosphine) and a mixture of silver and potassium carbonate in DMF at 80°C, such allenyl sulfones 

With such benefits offered by silver salts in these Heck-type reactions, chemists looked for similar improvements in other palladium-catalyzed couplings and related reactions. 

---