The nontoxic cyanide source K4[Fe(CN)6]⋅3 H2O can be used for the cyanation of (hetero)aryl halides. The application of palladacycle catalysts prevents poisoning during catalyst formation, thereby allowing for low catalyst loadings, fast reaction times, and wide heterocyclic substrate scope.
“A General, Practical Palladium-Catalyzed Cyanation of (Hetero)Aryl Chlorides and Bromides”, Angew. Chem. Int. Ed., 2013, 52(38), 10035 - 10039.