NHC‐Ligand Effectiveness in the Fluorine‐Free Hiyama Reaction of Aryl Halides

1‐Benzyl‐3‐(2‐hydroxy‐2‐phenylethyl)imidazolium chloride ( 5 ), which is a precursor of an N‐heterocyclic carbene ligand, in combination with palladium acetate, has been employed as an effective catalyst for the fluorine‐free Hiyama reaction. A systematic study of the catalytic mixture, by a 3 2 factorial design, has revealed that both the amount of palladium and the Pd/NHC precursor ratio are important factors for obtaining good yields of the coupling products, indicating an interaction between them. The best catalytic system involves mixing 0.1 mol‐% palladium acetate in a 1:5 ratio (Pd/salt 5 ), which allows the effective coupling of a range of aryl bromides and chlorides with trimethoxy(phenyl)silane. The Hiyama reactions are carried out in NaOH solution (50 % H 2 O w/w), at 120 °C under microwave irradiation during 60 min.