Palladium-Catalyzed Removable 8-Aminoquinoline Assisted Chemo- and Regioselective Oxidative sp-C-H/sp-C-H Cross-Coupling of Ferrocene with Toluene Derivatives.

The coupling of the C(sp)-H bond of ferrocene with toluene avoiding in situ functionalization of both coupling partners has been achieved using palladium and iron dual catalysis. This cross oxidative coupling features regioselectivity to primary and secondary C(sp)-H bonds and chemoselectivity toward the -C(sp)-H over C-I bond of toluene with gram-scale production. It seems Fe(II) catalyst not only stabilizes the generated benzyl radical but also tames its oxidizing behavior, and consequently transfers it to the palladacycle for C-C coupling.