title: Polyaniline-Induced Arylation with Arenediazonium Salts Derived from Anilines.
abstract: A catalytic amount of a reduced form of polyaniline (a redox-active π-conjugated polymer) was found to induce C-H direct arylation of (hetero)arenes with arenediazonium salts prepared from anilines with methanesulfonic acid (MeSO3H) and tert-butyl nitrite (tBuONO). The difficult part of this method is the coexistence of an oxidant and a reductant in this sequential diazotization and arylation system; diazotization requires weak oxidants such as alkyl nitrites, whereas the arylation is induced by a reductant. This was achieved by the careful control of the amount of tBuONO (1.0 equivalent) for the diazotization step, and sequential arylation using 5 mol % of the polyaniline. The reaction took place under mild conditions without any metals or strong bases at room temperature, and the amino group is a formal leaving group. The scope of the substrates demonstrates the versatility in the combination of anilines with a variety of functional groups and several (hetero)arenes. Two-directional arylation for the synthesis of an unsymmetrical 1,4-diarylated (furyl and pyrrolyl groups) benzene was achieved, using mono-Boc-protected 1,4-phenylenediamine as a substrate. This shows potential for the synthesis of more complicated oligoarene compounds.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamada-oka, Suita, Osaka, 565-0871, Japan.
authors.forename: Dai
authors.initials: D
authors.lastname: Hata
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamada-oka, Suita, Osaka, 565-0871, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Moriuchi
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamada-oka, Suita, Osaka, 565-0871, Japan.|The Institute of Scientific and Industrial Research, Osaka University, Mihoga-oka, Ibaraki, Osaka, 567-0047, Japan.
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Hirao
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamada-oka, Suita, Osaka, 565-0871, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Amaya
keywords: C−C coupling; Gomberg-Bachmann reaction; diazo compounds; polyaniline; radical reactions