Photoredox/Nickel Dual Catalytic C(sp2)S Cross‐coupling of Bromoanilines Enabled by Mineral Acids

Abstract

Cross‐coupling reactions are essential tools in modern organic synthesis, enabling the formation of carbonheteroatom (CX) bonds. Despite significant advancements in method development, particularly with palladium, copper, and nickel catalysis, including recent progress in photoredox catalysis, their efficiency is often limited when sensitive functional groups, such as thiols and amines, are present in the nucleophile or electrophile, and typically requires extensive protection–deprotection strategies. Herein, a practical synthetic approach is reported that employs mineral acids as unconventional reagents to facilitate C(sp2)S cross‐coupling between bromoanilines (or other electrophiles bearing free primary amines as functional groups) and thiols, thereby eliminating the need for protecting group manipulations. Additionally, protonation alters the electronic influence of the aniline moiety, transforming it from an electron‐donating to an electron‐withdrawing group, which promotes oxidative addition, and the acidic medium suppresses polythiolate formation, enhancing nickel catalysts’ accessibility and reducing inner filter effects in photocatalysis. This strategy enables efficient and high‐yielding synthesis of amino thioethers across a broad substrate scope, underscoring the value of acid‐assisted cross‐coupling as a streamlined and robust photoredox methodology for C(sp2)S bond formation.