para-Selective C–H alkylation via phosphonium-directed radical tele-substitution

Alkylated arenes are valuable scaffolds in pharmaceuticals, agrochemicals, and materials science. In this work, Ohmiya, Nagao, and co-workers report a radical para-selective alkylation of aroyl chlorides via a unique tele-substitution mechanism mediated by aroyl trialkylphosphonium intermediates. This metal-free strategy proceeds under mild conditions and enables functionalization without the pre-installation of directing groups onto the arenes.