Simple and Convenient Synthetic Procedure Leading to Ruthenium Olefin Metathesis Catalysts Bearing the N,N‘-Bis(mesityl)imidazol-2-ylidene (IMes) Ligand

The highly active olefin metathesis catalyst precursors RuCl2(CHR‘)(IMes)(PR3)2 (R‘ = Ph, R = Cy (4), R‘ = CHCMe2, R = Cpy (5)) can be conveniently synthesized from their phosphine analogues RuCl2(CHR‘)(PR3)2 (R‘ = Ph, R = Cy (cyclohexyl) (2), R‘ = CHCMe2, R = Cpy (cyclopentyl) (3)), imidazolium salts, and a base by a facile procedure. The ligand exchange reaction is performed in a “one-pot” procedure, and an easy workup leads to good yields of 4 and 5.