Single-Electron-Transfer (SET)-Induced Oxidative Biaryl Coupling by Polyalkoxybenzene-Derived Diaryliodonium(III) Salts

• Published in: Chemistry : a European journal Vol. 19; no. 44; pp. 15004 - 15011
• Main Authors: Yamaoka, Nobutaka, Sumida, Kohei, Itani, Itsuki, Kubo, Hiroko, Ohnishi, Yusuke, Sekiguchi, Sho, Dohi, Toshifumi, Kita, Yasuyuki
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 25.10.2013; WILEY‐VCH Verlag; Wiley; Wiley Subscription Services, Inc
• Subjects: Aromatic compounds; Benzene Derivatives - chemistry; biaryls; Catalysis; Cations; Chemistry; Chemistry, Multidisciplinary; cross coupling; Electron Transport; Electrons; hypervalent compound; iodine; Joining; Ligands; Onium Compounds - chemistry; Oxidants; Oxidation; Oxidative Coupling; Oxidizing agents; Physical Sciences; radical ions; Radicals; Science & Technology; umpolung; radical ions; cross coupling; ONE-POT SYNTHESIS; umpolung; NUCLEOPHILIC-SUBSTITUTION; hypervalent compound; EFFICIENT SYNTHESIS; PHENOL ETHER DERIVATIVES; AROMATIC-COMPOUNDS; INTRAMOLECULAR CYCLIZATION; biaryls; HETEROAROMATIC IODONIUM SALTS; UNIFIED MECHANISTIC ANALYSIS; iodine; HYPERVALENT IODINE(III) REAGENT; DIPHENYLIODONIUM HALIDES
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201301148

Metal‐free oxidative CC coupling by using polyalkoxybenzene‐derived diaryliodonium(III) salts as both the oxidant and aryl source has been developed. These salts can induce single‐electron‐transfer (SET) oxidation to yield electron‐rich arenes and subsequently transfer the polyalkoxyphenyl group into in situ generated aromatic radical cations to produce biaryl products. The reaction is promoted by a Lewis acid that activates the iodonium salts. It has been revealed that the reactivity of the salts under acidic conditions is quite different to their known behavior under basic conditions. The reactivity preference of a series of iodonium salts in the SET oxidation and their ligand transfer abilities have been systematically investigated and the results are summarized in this report. Coupling in the pair: Metal‐free oxidative CC coupling to yield electron‐rich biaryls has been achieved by using polyalkoxybenzene‐derived diaryliodonium(III) salts as both the oxidant and aryl source. These salts can induce single‐electron‐transfer (SET) oxidation towards electron‐rich aromatic compounds and subsequently transfer the polyalkoxyphenyl group into in situ generated aromatic radical cations to produce biaryl products (see scheme).