Evidence of CuI/CuII Redox Process by X‐ray Absorption and EPR Spectroscopy: Direct Synthesis of Dihydrofurans from β‐Ketocarbonyl Derivatives and Olefins |
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Authors: | Hong Yi Zhixiong Liao Guanghui Zhang Guoting Zhang Chao Fan Xu Zhang Prof. Dr. Emilio E. Bunel Dr. Chih‐Wen Pao Prof. Dr. Jyh‐Fu Lee Prof. Dr. Aiwen Lei |
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Affiliation: | 1. 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/;2. Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Ave. Argonne, IL 60439 (USA);3. National Synchrotron Radiation Research Center, Hsinchu 30076 (Taiwan);4. National Research Center for Carbohydrate Synthesis, Jiangxi Normal University, Nanchang 330022, Jiangxi, (P. R. China) |
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Abstract: | The CuI/CuII and CuI/CuIII catalytic cycles have been subject to intense debate in the field of copper‐catalyzed oxidative coupling reactions. A mechanistic study on the CuI/CuII redox process, by X‐ray absorption (XAS) and electron paramagnetic resonance (EPR) spectroscopies, has elucidated the reduction mechanism of CuII to CuI 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 CuI 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. |
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Keywords: | copper homogeneous catalysis oxidative coupling redox chemistry X‐ray absorption spectroscopy |
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