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.