Polyaniline-Induced Arylation with Arenediazonium Salts Derived from Anilines

5 years ago

Polyaniline-Induced Arylation with Arenediazonium Salts Derived from Anilines

Toshiyuki Moriuchi, Dai Hata, Toshikazu Hirao, Toru Amaya

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. Slow and steady wins the race: A catalytic amount of a reduced form of polyaniline induced C−H direct arylation of (hetero)arenes with arenediazonium salts, which were prepared from anilines using methanesulfonic acid (MeSO3H) and tert-butyl nitrite (tBuONO). Exploiting mono-Boc-protected 1,4-phenylenediamine, two-directional arylation towards the synthesis of a unsymmetrically 1,4-diarylated (furyl and pyrrolyl groups) benzene was also achieved.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/chem.201700630