Hori Mitsuki, Guo Jing-Dong, Yanagi Tomoyuki, Nogi Keisuke, Sasamori Takahiro, Yorimitsu Hideki
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan.
Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan.
Angew Chem Int Ed Engl. 2018 Apr 16;57(17):4663-4667. doi: 10.1002/anie.201801132. Epub 2018 Mar 13.
Metal-free dehydrogenative couplings of aryliodanes with phenols to afford 2-hydroxy-2'-iodobiaryls have been developed. This reaction proceeds through ligand exchange on the hypervalent iodine atom followed by a [3,3] sigmatropic rearrangement and with complete regioselectivity. This coupling, in combination with in situ oxidation by mCPBA, enables the convenient conversion of iodoarenes into desirable biaryls. The obtained biaryls have convertible iodo and hydroxy groups in close proximity, and are thus synthetically useful, as exemplified by the controlled syntheses of π-extended furans and a substituted [5]helicene. DFT calculations clearly revealed that the rearrangement is sigmatropic, with C-C bond formation and I-O bond cleavage proceeding in a concerted manner. Acetic acid, which was found to be the best solvent for this protocol, renders the iodine atom more cationic and thus accelerates the sigmatropic rearrangement.
已开发出芳基碘烷与苯酚的无金属脱氢偶联反应，以生成2-羟基-2'-碘联芳基。该反应通过高价碘原子上的配体交换，随后进行[3,3]σ迁移重排，且具有完全的区域选择性。这种偶联反应与间氯过氧苯甲酸（mCPBA）的原位氧化相结合，能够方便地将碘代芳烃转化为所需的联芳基。所得到的联芳基在紧邻位置具有可转化的碘基和羟基，因此具有合成实用性，例如在π-扩展呋喃和取代的[5]螺旋烯的可控合成中得到了体现。密度泛函理论（DFT）计算清楚地表明，该重排是σ迁移重排，碳-碳键的形成和碘-氧键的断裂是协同进行的。已发现乙酸是该反应体系的最佳溶剂，它使碘原子更具阳离子性，从而加速了σ迁移重排。
