Biasing mechanistically distinct reaction pathways by mechanochemistry

Abstract

Due to the solvent-free nature of the mechanochemical approach, it offers an opportunity to drive reactions with different selectivities from those under conventional solution-based conditions. Nevertheless, literature examples of pathway switching remain scarce. Herein, we report an unusual example where ball-milling offers three distinct pathways leading to three different products. By simply adjusting the amount of liquid additive, arene C–H functionalization can be biased between bromination and oxidation via either radical (Br˙) or ionic (Br⁺) intermediates, respectively.