Ruthenium Carbene Complexes with Imidazolin-2-ylidene Ligands Allow the Formation of Tetrasubstituted Cycloalkenes by RCM

Chemically quite robust ruthenium carbene complexes 2–8 bearing one or two imidazolin-2-ylidene ligands are highly active catalysts for all types of ring closing metathesis reactions (RCM). Importantly, they even allow the formation of tetrasubstituted alkenes that were previously out of reach of ruthenium-based metathesis catalysts