title: Evidence of Cu(I)/Cu(II) Redox Process by X-ray Absorption and EPR Spectroscopy: Direct Synthesis of Dihydrofurans from β-Ketocarbonyl Derivatives and Olefins.
abstract: The Cu(I)/Cu(II) and Cu(I)/Cu(III) catalytic cycles have been subject to intense debate in the field of copper-catalyzed oxidative coupling reactions. A mechanistic study on the Cu(I)/Cu(II) redox process, by X-ray absorption (XAS) and electron paramagnetic resonance (EPR) spectroscopies, has elucidated the reduction mechanism of Cu(II) to Cu(I) by 1,3-diketone and detailed investigation revealed that the halide ion is important for the reduction process. The oxidative nature of the thereby-formed Cu(I) has also been studied by XAS and EPR spectroscopy. This mechanistic information is applicable to the copper-catalyzed oxidative cyclization of β-ketocarbonyl derivatives to dihydrofurans. This protocol provides an ideal route to highly substituted dihydrofuran rings from easily available 1,3-dicarbonyls and olefins.
authors.affiliation: College of Chemistry and Molecular Sciences, the Institute for Advanced Studies (IAS), Wuhan University, Wuhan, Hubei 430072 (P. R. China) http://aiwenlei.whu.edu.cn/Main_Website/
authors.forename: Hong
authors.initials: H
authors.lastname: Yi
authors.affiliation: College of Chemistry and Molecular Sciences, the Institute for Advanced Studies (IAS), Wuhan University, Wuhan, Hubei 430072 (P. R. China) http://aiwenlei.whu.edu.cn/Main_Website/
authors.forename: Zhixiong
authors.initials: Z
authors.lastname: Liao
authors.affiliation: College of Chemistry and Molecular Sciences, the Institute for Advanced Studies (IAS), Wuhan University, Wuhan, Hubei 430072 (P. R. China) http://aiwenlei.whu.edu.cn/Main_Website/
authors.forename: Guanghui
authors.initials: G
authors.lastname: Zhang
authors.affiliation: College of Chemistry and Molecular Sciences, the Institute for Advanced Studies (IAS), Wuhan University, Wuhan, Hubei 430072 (P. R. China) http://aiwenlei.whu.edu.cn/Main_Website/
authors.forename: Guoting
authors.initials: G
authors.lastname: Zhang
authors.affiliation: College of Chemistry and Molecular Sciences, the Institute for Advanced Studies (IAS), Wuhan University, Wuhan, Hubei 430072 (P. R. China) http://aiwenlei.whu.edu.cn/Main_Website/
authors.forename: Chao
authors.initials: C
authors.lastname: Fan
authors.affiliation: College of Chemistry and Molecular Sciences, the Institute for Advanced Studies (IAS), Wuhan University, Wuhan, Hubei 430072 (P. R. China) http://aiwenlei.whu.edu.cn/Main_Website/
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Ave. Argonne, IL 60439 (USA).
authors.forename: Emilio E
authors.initials: EE
authors.lastname: Bunel
authors.affiliation: National Synchrotron Radiation Research Center, Hsinchu 30076 (Taiwan).
authors.forename: Chih-Wen
authors.initials: CW
authors.lastname: Pao
authors.affiliation: National Synchrotron Radiation Research Center, Hsinchu 30076 (Taiwan).
authors.forename: Jyh-Fu
authors.initials: JF
authors.lastname: Lee
authors.affiliation: College of Chemistry and Molecular Sciences, the Institute for Advanced Studies (IAS), Wuhan University, Wuhan, Hubei 430072 (P. R. China) http://aiwenlei.whu.edu.cn/Main_Website/. aiwenlei@whu.edu.cn.|National Research Center for Carbohydrate Synthesis, Jiangxi Normal University, Nanchang 330022, Jiangxi, (P. R. China). aiwenlei@whu.edu.cn.
authors.forename: Aiwen
authors.initials: A
authors.lastname: Lei
keywords: X-ray absorption spectroscopy; copper; homogeneous catalysis; oxidative coupling; redox chemistry