期刊
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
卷 134, 期 37, 页码 15512-15518出版社
AMER CHEMICAL SOC
DOI: 10.1021/ja306120n
关键词
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资金
- U.S. DOE [DE-FG0297ER14807]
- Department of Energy Office of Science Graduate Fellowship Program (DOE SCGF)
- ORISE-ORAU [DE-AC05-06OR23100]
- National Science Foundation [CHE-0840451]
- National Institutes of Health [1S10RR25431-1A1]
The reaction of CpCr(CO)(3)H with activated alkynes in benzene has been examined. The kinetics of these reactions have been studied with various alkynes, along with the stereochemistry with which the alkynes are hydrogenated. The hydrogenation of phenyl acetylene and diphenyl acetylene with CpCr(CO)(3)H has been shown to occur by a hydrogen atom transfer (HAT) mechanism. The reaction of CpCr(CO)(3)H with dimethyl acetylenedicarboxylate (DMAD) produced hydrogenated products as well as phenyl substitution from reaction with solvent. On the basis of kinetic data, it is thought that the reaction of DMAD may proceed via a single electron transfer (SET) as the rate-determining step. The radical anion of dimethylfumarate was observed by EPR spectroscopy during the course of the reaction, supporting this claim. The aromatic 1,6 eneyne (8) gave cyclized products in 78% yield under catalytic conditions (35 psi H-2), presumably by the 5-exo-trig cyclization of the vinyl radical arising from H center dot transfer. Using a cobaloxime catalyst (12) hydrogenation was completely eliminated to yield 100% cyclized products.
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