Direct Arylation of Alkenes with Aryl Iodides/Bromides through an Organocatalytic Radical Process
Direct Arylation of Alkenes with Aryl Iodides/Bromides through an Organocatalytic Radical Process
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DOI：
10.1002/chem.201101562
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发表时间：
2011-09-01
影响因子：
4.3
通讯作者：
Shi, Zhang-Jie
中科院分区：
文献类型：
--
作者：
Sun, Chang-Liang;Gu, Yi-Fan;Shi, Zhang-Jie
Radical addition into a carbon–carbon double bond is a fundamental and important process in radical chemistry.[1] The intramolecular radical addition to a C= C bond is regarded as an efficient tool for cyclization and has been widely developed and applied into organic synthesis.[2] In general, aryl radicals can be generated through many methods to process the radical addition.[3–5] For example, diazo compounds [4] and diaroyl peroxides [5] are efficient precursors to initiate the homolytic cleavage of ArÀX to generate aryl radicals. Recently, Itami and co-workers reported a KOtBupromoted coupling of electron-deficient nitrogen heterocycles with aryl iodides.[6] Later, we and other groups reported additional examples of transition-metal-free couplings of arenes with aryl halides, which were promoted by KOtBu together with a catalytic amount of phenanthroline derivatives or DMEDA (N, N’-dimethylethane-1, 2-diamine).[7] Such a reported process is now identified as a new radical pathway. To confirm the radical intermediate in our previous investigation, we carried out the addition of 4-iodoanisole (1a) towards 1, 1-diphenylethylene (2a) in the presence of nBu3SnH and an alkene hydroarylation product was observed albeit in a low yield (Scheme 1).[7a] We envision that, in the absence of the hydrogen source, such aryl radicals might undergo an addition to a C= C bond followed by hydrogen elimination to carry out the arylation of olefins. With this idea in mind, 1, 1-diphenylethylene (2a) was selected as the substrate. The arylation of 2a was obtained under suitable conditions in the presence of KOtBu and various dinitrogen compounds (Table 1). After screening several catalysts, we found that bathophenanthroline (bathophen)[a] C.-L. Sun, Y.-F. Gu, Prof. Dr. Z.-J. Shi Beijing National Laboratory of Molecular Sciences (BNLMS) Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education College of Chemistry and Molecular Engineering Peking University, Beijing 100871 (PR China) Fax:(+ 86) 10-6276-0890 E-mail: zshi@ pku. edu. cn [b] Prof. Dr. B. Wang Department of Medicinal Chemistry, Nakai University Tianjin 300071 (PR China)[c] Prof. Dr. Z.-J. Shi State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic Chemistry Chinese Academy of Sciences, Shanghai 200032 (PR China)
