Cross-coupling reactions between aromatic rings and alkyl chains has attracted significant attention over the past decade due to the advent of metal-catalyzed photoredox reactions. These transformations significantly improved access to C(sp2)–C(sp3) bonds compared to traditional Friedel-Crafts alkylations. Unfortunately, these photoredox methods require the use of pre-functionalized arenes such as aryl halides, aryl pseudo-halides, or other moieties amenable to oxidative additions by transition-metal catalysts. Enabling the direct alkylation of unfunctionalized and unactivated aromatic rings would represent a more straightforward approach with possible applications in late-stage alkylations and modifications of complex arene moieties in bioactive molecules. Our research has been focused on the development of metal-free approaches to generate alkyl radicals from alkyl halides amenable to functionalized C(sp2)–H bonds across aromatic rings. Herein, we present a photoinduced halogen-atom-transfer process that enables the direct alkylation of unactivated arenes. The reaction proceeds efficiently with a wide variety of alkyl iodides in the presence of important functional groups and affords the desired alkylated aromatic rings. Importantly, this method enables these transformations with both simple and complex arenes containing bioactive motifs and natural products derivatives.

Direct alkylation of aromatic rings via photoinduced halogen-atom-transfer

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