A Series of Well‐Defined Metathesis Catalysts–Synthesis of [RuCl₂(CHR′)(PR₃)₂] and Its Reactions

Substantially better initiators and therefore considerably more reactive than complexes of type A, the novel metathesis catalysts B are easily prepared by the reaction of [RuCl2(PPh3)3] with the appropriate diazoalkanes and subsequent phosphane exchange. While the PPh3 derivatives are excellent catalysts for living ROMP of norbornene, the complex with R = Cy, R′ = Ph is also a very efficient catalyst for the metathesis of acyclic alkenes.