Hydrogenation of Anthracene and Nitrogen Heterocycles Catalyzed by Iron Pentacarbonyl under Water-Gas Conditions

Article abstract of DOI:10.1021/jo00181a026

Iron pentacarbonyl in the presence of H2O, CO, base and a phase-transfer agent catalyzes the reduction of quinoline regiospecifically in the nitrogen-containing ring at temperaturee between 150 and 300 deg C.The best yield ( 87 turnovers) is obtained in the presence of 18-crown-6 ether as phase-transfer agent.Anthracene is reduced to 9,10-dihydroanthracene by the same system, which becomes catalytic (17 turnovers) with the addition of bipyridine or terpyridine and tetra-n-butylammonium iodide as phase-transfer agent.The phenanthrolines (4,7 or 1,10) are also regiospecifically reduced in one of the nitrogen-containing rings (71 percent or 50 percent yield, respectively, without optimization).With 9,10-dimethylanthracene, nearly equal amounts of both cis- and trans-9,10-dihydro-9,10-dimethylanthracene are obtained.Aromatic coal constituents such as pyrene, chrysene, or dibenzothiophene are not reduced under these conditions; a reduction potential > -2.0 V seems to be required to achieve hydrogenation in this system.A electron-transfer process is indicated.