Copper-Catalyzed Alkyl鈥揂lkyl Cross-Coupling Reactions Using Hydrocarbon Additives: Efficiency of Catalyst and Roles of Additives

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• 作者：Takanori Iwasaki ; Reiko Imanishi ; Ryohei Shimizu ; Hitoshi Kuniyasu ; Jun Terao ; Nobuaki Kambe
• 刊名：Journal of Organic Chemistry
• 出版年：2014
• 出版时间：September 19, 2014
• 年：2014
• 卷：79
• 期：18
• 页码：8522-8532
• 全文大小：727K
• ISSN：1520-6904

文摘

Cross-coupling of alkyl halides with alkyl Grignard reagents proceeds with extremely high TONs of up to 1230000 using a Cu/unsaturated hydrocarbon catalytic system. Alkyl fluorides, chlorides, bromides, and tosylates are all suitable electrophiles, and a TOF as high as 31200 h^鈥? was attained using an alkyl iodide. Side reactions of this catalytic system, i.e., reduction, dehydrohalogenation (elimination), and the homocoupling of alkyl halides, occur in the absence of additives. It appears that the reaction involves the 尾-hydrogen elimination of alkylcopper intermediates, giving rise to olefins and Cu鈥揌 species, and that this process triggers both side reactions and the degradation of the Cu catalyst. The formed Cu鈥揌 promotes the reduction of alkyl halides to give alkanes and Cu鈥揦 or the generation of Cu(0), probably by disproportionation, which can oxidatively add to alkyl halides to yield olefins and, in some cases, homocoupling products. Unsaturated hydrocarbon additives such as 1,3-butadiene and phenylpropyne play important roles in achieving highly efficient cross-coupling by suppressing 尾-hydrogen elimination, which inhibits both the degradation of the Cu catalyst and undesirable side reactions.