The synthesis of 1,3-dialkyl-4-methylimidazolinium salts and their application in palladium catalyzed Heck coupling reactions

Seven novel 1,3-dialkyl-4-methylimidazolinium chloride salts 3a–g were prepared as precursors of N-heterocyclic carbenes by reacting N,N’-alkyl-1,2-diaminopropane, triethyl orthoformate, and ammonium chloride. The salts were characterized spectroscopically. The in situ prepared palladium complexes derived from the imidazolinium salts and palladium acetate were used as catalyst in Heck coupling reactions between aryl bromides and styrene. The corresponding Heck products were obtained in good yields.