Olefin metathesis catalysts: Recent progress

This article summarizes recent progress in transition-metal catalysts for olefin metathesis reactions, in terms of their catalytic activity, stability, and accessibility. Catalytic olefin metathesis reactions are now being one of the most efficient methods of constructing C-C bonds in organic and polymer synthesis. Since Grubbs et al. have discovered that alkylideneruthenium complexes possess high catalytic activity and wide tolerance of functional groups, a number of well-defined ruthenium-based catalysts have been developed. Some of them show greatly enhanced activity and thermal stability, as compared with the original Grubbs' catalyst. In addition, the complexes having a metal-carbon unsaturated bond, including vinylidene, allenylidene, Fischer-type carbene, and carbyne complexes, are found to be active for olefin metathesis catalysts (or catalyst precursors).