Ruthenium-Catalyzed Novel Carbon-Carbon Bond Forming Reactions via Ruthenium-Allenylidene Complexes

Our recent studies on novel carbon-carbon bond forming reactions using propargylic alcohols catalyzed only by thiolate-bridged diruthenium complexes are reviewed from the viewpoint of organic synthesis. The reactions are substitutions of hydroxyl group of the alcohols with a variety of carbon-centered nucleophiles such as simple ketones, cyclic 1,3-dicarbonyl compounds, aromatic and heteroaromatic compounds, phenols, naphthols, and alkenes. The asymmetric version of propargylic alkylation with acetone is also described. All of the reactions are considered to proceed via ruthenium-allenylidene complexes as key intermediates.