Neopentylglycolborylation of ortho-Substituted Aryl Halides Catalyzed by NiCl2-Based Mixed-Ligand Systems

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• 作者：Costel Moldoveanu ; Daniela A. Wilson ; Christopher J. Wilson ; Pawaret Leowanawat ; Ana-Maria Resmerita ; Chi Liu ; Brad M. Rosen ; Virgil Percec
• 刊名：Journal of Organic Chemistry
• 出版年：2010
• 出版时间：August 20, 2010
• 年：2010
• 卷：75
• 期：16
• 页码：5438-5452
• 全文大小：1448K
• 年卷期：v.75,no.16(August 20, 2010)
• ISSN：1520-6904

文摘

NiCl₂-based mixed-ligand systems were shown to be very effective catalysts for the neopentylglycolborylation of aryl iodides, bromides, and chlorides bearing electron-rich and electron-deficient ortho-substituents. Although NiCl₂-based single-ligand catalytic systems were able to mediate neopentylglycolborylation of selected substrates, they were not as effective for all substrates, highlighting the value of the mixed-ligand concept. Optimization of the Ni(II)-catalyzed neopentylglycolborylation of 2-iodoanisole and methyl 2-iodobenzoate demonstrated that, while the role of ligand and coligand in the conversion of Ni(II) precatalyst to Ni(0) active catalyst cannot be ignored, a mixed-ligand complex is likely present throughout the catalytic cycle. In addition, protodeborylation and hydrodehalogenation were demonstrated to be the predominant side reactions of Ni(II)-catalyzed borylation of ortho-substituted aryl halides containing the electron-deficient carboxylate substituents. Ni(II) complexes in the presence of H₂O and Ni(0) are responsible for the catalysis of these side reactions.