Ruthenium Indenylidene Complexes METATHESIS CATALYSTS WITH ENHANCED ACTIVITY

This paper describes a class of ruthenium indenylidene complexes which constitute robust and efficient pre-catalysts for olefin metathesis reactions, specifically ring-closing metathesis of substituted linear dienes, acyclic diene metathesis of alpha,omega-dienes, enyne metathesis and ring-opening metathesis polymerisation of cycloolefins. They readily allow reactions not promoted by many prior ruthenium catalysts, such as the synthesis of tri- and tetrasubstituted cycloalkenes as well as ring-closing metathesis involving highly substituted dienes. The activity and stability of these pre-catalysts can be finely tuned by adjusting both steric and electronic effects in the metal coordination sphere through an appropriate selection of ancillary ligands. Due to their accessibility, enhanced activity and good stability, this class of ruthenium complexes gratifyingly extends the scope and utility of the currently used metathesis catalysts.