Ruthenium-catalyzed addition of 3′-methyl-, 3′-trifluoromethyl-, and 3′-N,N-dimethylaminoacetophenones to an olefin proceeds site selectively at 6′ CH bonds to give the 1:1 CH/olefin addition products in high yields. In contrast, the addition of 3′-methoxyacetophenone takes place preferentially at the CH bond at the more congested 2′ position.
To obtain further insight into the new ruthenium-catalyzed reaction of carbon–hydrogenbonds in aromatic ketones with olefins, the effect of various substituents at the aromatic ring is examined. Reaction of o-methylacetophenone with triethoxyvinylsilane (2) in the presence of [Ru(H)2(CO)(PPh3)3] (3)as the catalyst gave the 1 : 1 addition product in quantitative yield. Similarly, the ketone having