A Visible Light and Iron‐mediated Carbocationic Route to Polysubstituted 1‐Halonaphthalenes by Benzannulation using Allylbenzenes and Polyhalomethanes

A wide array of polysubstituted 1‐bromo and chloronaphthalenes are obtained from coupling of allylbenzenes and polyhalomethanes. The reaction is mediated by iron metal under visible light irradiation and proceeds via a Kharasch addition intermediate followed by intramolecular FeIII mediated Friedel‐Crafts alkylation, with the formation of two Csp2−Csp2 bonds in the process. This method gives easy access to 1‐halonaphthalenes with substituent(s) at C‐5 to C‐8 that are otherwise hard to synthesize.