α‑Chlorobenzylation of Nitroarenes via Vicarious Nucleophilic Substitution with Benzylidene Dichloride: Umpolung of the Friedel–Crafts Reaction

Readily available α,α-dichlorotoluenes enter a vicarious nucleophilic substitution (VNS) reaction with electron-deficient arenes to give α-chlorobenzylated nitrobenzenes, as well as six- and five-membered heterocycles. Oxidation of the initially formed α-chlorobenzylic carbanions instead of protonation results in formation of diaryl ketones, providing a means for overall nucleophilic C–H benzoylation of electron-deficient aromatic rings. Alternatively, benzoylated nitroarenes can be obtained via the reaction of isolated α-chlorodiarylmethanes with sodium azide.