We describe a method for the site-selective construction of C(aryl)-C(sp<sup>3</sup>) bond by the palladium-catalyzed direct allylation of arenes with allylic pivalates in the presence of AgOPiv to afford the linear (<i>E</i>)-allylated arene with excellent regioselectivity; this reaction occurs with arenes that have not undergone site- and stereoselective direct allylation previously, such as monofluorobenzenes and non-fluorinated arenes. The available mechanistic data are consistent with a synergistic catalytic process wherein the cleavage of an aryl C–H bond occurs by a phosphine-ligated AgOPiv complex; the resulting arylsilver species then transfers an aryl group to the (π-allyl)palladium pivalate species formed by oxidative-addition of an allylic pivalate to Pd(0). Subsequent C–C bond-forming reductive elimination affords the allylation product and regenerates the Pd(0) species. The proposed palladium and silver intermediates have been synthesized, unambiguously characterized by X-ray crystallography, and shown to be chemically and kinetically competent to be intermediates by the suggested elementary steps of the catalytic cycle.

Palladium-catalyzed, site-selective direct allylation of aryl C–H bonds by silver-mediated C–H activation: A synthetic and mechanistic investigation

253rd National Meeting (2017)

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