RU-3(CO)(12)-CATALYZED AND RH-4(CO)(12)-CATALYZED REACTIONS OF PYRIDYLOLEFINS OR N-(2-PYRIDYL)ENAMINES WITH CO AND OLEFINS - CARBONYLATION AT OLEFINIC C-H BONDS

This paper describes a study of the Ru-3(CO)(12)-catalyzed carbonylati on at an olefinic C-K bond. The reaction of pyridylolefins with CO and ethylene in the presence of a catalytic amount of Ru-3(CO)(12) in tol uene results in propionylation at an olefinic C-H bond in pyridylolefi ns. The carbonylation occurs regioselectively ata position gamma to th e pyridine nitrogen. Transition-metal complexes other than Ru3(CO)12 t hat have thus far been examined exhibit no catalytic activity, and eth ylene serves as the only olefin. A similar tendency has been noted in the previously reported carbonylation at a C-H bond in the benzene rin g of pyridylbenzenes. This reaction can be also applied to N-(2-pyridy l)enamines, in which an olefin unit is separated from the pyridine rin g by an sp(3)-nitrogen atom. The reaction of N-(2-pyridyl)enamines wit h CO and ethylene gives the corresponding ethyl ketones as the couplin g products. Interestingly, Rh-4(CO)(12) also shows high catalytic acti vity in the case of N-(2-pyridyl)enamines. In addition, olefins such a s propene, 1-hexene, 3,3-dimethyl-1-butene, styrene, cyclopentene, acr yl acid methyl ester, ethyl vinyl ether, and trimethylvinylsilane can also be used. This is in sharp contrast to the case of the carbonylati on at a C-H bond in pyridylbenzenes reported previously and to the res ults of pyridylolefins as mentioned above, where Ru-3(CO)(12) is the o nly active catalyst and hexene-cannot substitute for ethylene.