CATALYTIC ADDITION OF AROMATIC CARBON-HYDROGEN BONDS TO OLEFINS WITH THE AID OF RUTHENIUM COMPLEXES

Ruthenium complexes, e.g., Ru(H)(2)(CO)(PPh(3))(3), have been found to catalyze the addition of ortho C-H bonds of aromatic ketones to olefi ns with a high degree of efficiency and selectivity. 2'-Methylacetophe none reacts with various types of terminal olefins to give 1:1 couplin g products in good to excellent yields. The C-C bond formation takes p lace exclusively at the terminal carbon atom of olefins except for sty rene which affords a mixture of two regioisomers. Acetylnaphthalenes, cyclic aromatic ketones, and heteroaromatic ketones also react with tr iethoxyvinylsilane to give 1:1 addition products in virtually quantita tive yields. From 2'-acetonaphthone or 3-acetylthiophene, in which two different reaction sites are available, only one out of four possible regioisomers is obtained. The importance of the coordination of the o xygen atom of the ketone to ruthenium and the intervention of a cyclom etallation intermediate are suggested. A deuterium labeling experiment using acetophenone-d(5) and triethoxyvinylsilane shows that an H/D ex change between the aromatic and olefinic positions takes place to some extent, even prior to the formation of the product. This implies that the rate-determining step is not the C-H bond cleavage step, but the product forming step.