Convenient Route to Fischer-Type Carbene Ruthenium Complexes:  Highly Selective Catalysts for Ring Opening/Cross-Metathesis of Norbornene Derivatives

The Fischer-type ruthenium carbene complexes RuCl₂{C(H)ER}(PCy₃)₂ (ER = SPh (1a), SC₆H₄Me-p (1b), SC₆H₄Cl-p (1c), SC₆H₄OMe-p (1d), SePh (1e)) have been prepared by the reactions of Ru(p-cymene)(cod), PCy₃, and the corresponding dichloromethyl chalcogenides (Cl₂CHER) in 47−80% yields. The starting Ru(p-cymene)(cod) is readily synthesized in high yield from [RuCl₂(p-cymene)]₂. The X-ray structures of 1b and 1e are reported. Complexes 1a and 1e serve as highly selective catalysts for ring opening/cross-metathesis of norbornene derivatives with vinyl chalcogenides.