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DOI: 10.1055/sos-SD-103-00038

Hopkinson, M. N.; Gouverneur, V.Science of Synthesis Knowledge Updates, (20112102.

Gold(III) is known to selectively activate aromatic C–H bonds via an electrophilic aromatic substitution mechanism to give arylgold(III) complexes. In contrast to palladium and other late transition metals, this transformation can be performed under mild conditions without the need for directing groups on the arene. Oxidative functionalization of a nonactivated arene via C(sp2)–H bond functionalization was observed by Kharasch and co-workers in 1931.[‌36‌] Reacting gold(III) chloride with benzene results in the immediate evolution of hydrogen chloride gas with a concomitant color change from yellow to red. After a few minutes, the reaction mixture turns brown and bright yellow crystals of gold(I) chloride precipitate (97.7% yield; Scheme 2). The benzene solution contains chlorobenzene resulting from an oxidative chlorination process. The addition of diethyl ether to the reaction mixture prior to the precipitation of gold(I) chloride results in the formation of a bright yellow solution containing dichloro(phenyl)gold(III), which can be isolated in 18% yield upon evaporation of the solvents and recrystallization. Chlorobenzene most likely derives from reductive elimination from this or related complexes.

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