Dual-hatted phenacyl halide for visible-light-mediated de novo synthesis of regioselective ortho-halo-functionalized N-aryl α-keto amides.

Herein, we report a green and sustainable approach for the de novo synthesis of ortho-halo N-aryl α-keto amides via a room-temperature, metal-free, visible-light-induced pathway from readily available feedstocks. This protocol involves the formation of an N-aryl α-keto amide followed by regioselective ortho halogenation, without the need of pre-installation of a directing group. Here, phenacyl halide has been utilized as a source of halogen for the first time. Mechanistic investigation indicates the formation of a halide radical under visible-light-mediated conditions from hydrogen halide, generated in situ from phenacyl halide. This atom-economical protocol tolerates diverse functional groups, delivering excellent yields of the desired products. Gram-scale synthesis, product diversification and application to the synthesis of bromo-quinolines are other highlights of our protocol.