Showing papers by "Fumitoshi Kakiuchi published in 1998"

Transition Metal-Catalyzed Intramolecular Cyclization of 1,5- and 1,6-Dienes via Direct Cleavage and Addition of the Carbon–Hydrogen Bond

Abstract: Ruthenium- and rhodium-catalyzed intramolecular C–H/olefin coupling reactions of 1-(2-pyridyl)-, 1-(2-imidazolyl)-, and 1-(2-oxazolyl)-1,5-dienes proceeded in a regiospecific manner to give 5-membe...

New Protocol for the Siteselective Alkylation and Vinylation of Aromatic Compounds. Catalyst-Specific Reactions

Abstract: Catalyst-specific C-H/olefin as well as C-H/acetylene coupling has been accomplished for aromatics which contain both keto and imino substituents by simply changing the catalyst. By using Ru(H)2(CO...

Ruthenium-catalyzed reactions of acyclic α,β-enones with olefins and their reaction mechanisms

Abstract: The reaction of 4,4-dimethyl-5-phenyl-4-peneten-3-one with styrene (2) using Ru(H)2(CO)(PPh3)3 as the catalyst gave the stereochemically retained product. In the case of 2,2-dimethyl-4-hexen-3-one, the stereochemically inverted branched product was obtained. These results are consistent with two different reaction pathways operating, i.e. one involving a direct C-H bond cleavage and the other, a pathway involving hydrometallation.

Ru3(CO)12- and Rh4(CO)12-Catalyzed Reactions of Pyridylolefins or N-(2-Pyridyl)enamines with CO and Olefins. Carbonylation at Olefinic C-H Bonds

Abstract: This paper describes a study of the Ru3(CO)12-catalyzed carbonylation at an olefinic C−H bond. The reaction of pyridylolefins with CO and ethylene in the presence of a catalytic amount of Ru3(CO)12 in toluene results in propionylation at an olefinic C−H bond in pyridylolefins. The carbonylation occurs regioselectively at a position γ to the pyridine nitrogen. Transition-metal complexes other than Ru3(CO)12, that have thus far been examined exhibit no catalytic activity, and ethylene serves as the only olefin. A similar tendency has been noted in the previously reported carbonylation at a C−H bond in the benzene ring of pyridylbenzenes. This reaction can be also applied to N-(2-pyridyl)enamines, in which an olefin unit is separated from the pyridine ring by an sp3-nitrogen atom. The reaction of N-(2-pyridyl)enamines with CO and ethylene gives the corresponding ethyl ketones as the coupling products. Interestingly, Rh4(CO)12 also shows high catalytic activity in the case of N-(2-pyridyl)enamines. In additio...

Ruthenium-Catalyzed Addition of Carbon—Hydrogen Bonds in Aromatic Ketones to Olefins. The Effect of Various Substituents at the Aromatic Ring.

Abstract: To obtain further insight into the new ruthenium-catalyzed reaction of carbon–hydrogen bonds 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 an o-CF3 group gave the coupling product 9 in 92% yield. However, ortho substituents such as OMe, F, and CN, seem to react with and kill the catalyst so that no efficient reaction was attained. In the cases of the reactions of p-methoxy- and p-fluoroacetophenones with 2, the corresponding 1 : 2 addition products were obtained as the major products. In the cases of m-substituted acetophenones, two different C–H bonds at the ortho positions are available. The C–C bond formation preferentially occurred at the sterically less congested positions. Exceptions are the reactions of m-methoxy- and m-fluoroacetophenones, ...

Rhodium-Catalyzed Reaction of N-Acylpiperazines with CO and Ethylene. Carbonylation at a C—H Bond Directed by an Amido Group.

Abstract: The reaction of N -acylpiperazines with CO (15 atm) and ethylene at 160 °C in the presence of Rh 4 (CO) 12 results in dehydrogenation and carbonylation at a C-H bond. This reaction represents the first example of carbonylation at a C-H bond promoted by an oxygen functional group. © 1997 Elsevier Science Ltd.

Transition Metal-Catalyzed Intramolecular Cyclization of 1,5- and 1,6-Dienes via Direct Cleavage and Addition of the Carbon—Hydrogen Bond.

Abstract: Ruthenium- and rhodium-catalyzed intramolecular C–H/olefin coupling reactions of 1-(2-pyridyl)-, 1-(2-imidazolyl)-, and 1-(2-oxazolyl)-1,5-dienes proceeded in a regiospecific manner to give 5-membe...

Ru3(CO)12- and Rh4(CO)12-Catalyzed Reactions of Pyridylolefins or N-(2-Pyridyl)enamines with CO and Olefins. Carbonylation at Olefinic C—H Bonds.

Abstract: This paper describes a study of the Ru3(CO)12-catalyzed carbonylation at an olefinic C−H bond The reaction of pyridylolefins with CO and ethylene in the presence of a catalytic amount of Ru3(CO)12 in toluene results in propionylation at an olefinic C−H bond in pyridylolefins The carbonylation occurs regioselectively at a position γ to the pyridine nitrogen Transition-metal complexes other than Ru3(CO)12, that have thus far been examined exhibit no catalytic activity, and ethylene serves as the only olefin A similar tendency has been noted in the previously reported carbonylation at a C−H bond in the benzene ring of pyridylbenzenes This reaction can be also applied to N-(2-pyridyl)enamines, in which an olefin unit is separated from the pyridine ring by an sp3-nitrogen atom The reaction of N-(2-pyridyl)enamines with CO and ethylene gives the corresponding ethyl ketones as the coupling products Interestingly, Rh4(CO)12 also shows high catalytic activity in the case of N-(2-pyridyl)enamines In additio