Sigmatropic Rearrangements of Hypervalent‐Iodine‐Tethered Intermediates for the Synthesis of Biaryls |
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| Authors: | Mitsuki Hori Dr Jing‐Dong Guo Tomoyuki Yanagi Dr Keisuke Nogi Prof Dr Takahiro Sasamori Prof Dr Hideki Yorimitsu |
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| Institution: | 1. Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, Japan;2. Institute for Chemical Research, Kyoto University, Kyoto, Japan;3. Graduate School of Natural Sciences, Nagoya City University, Aichi, Japan |
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| Abstract: | 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. |
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| Keywords: | biaryls dehydrogenative couplings density functional calculations hypervalent iodine compounds sigmatropic rearrangements |
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