Mechanochemical Ball Milling Approach to C(sp³)‐H Functionalization of 8‐Methylquinolines

Abstract A mechanochemical, highly regioselective rhodium(III)‐catalyzed C─H methylation of 8‐methylquinolines is reported. The methylation method reported in this study, is often solvent‐free or uses minimal solvent (liquid assisted grinding), operates without external heating under mild reaction conditions, demonstrating tolerance for various functional groups. Moreover, the reaction time is significantly reduced compared to the solvent‐based variant. Notably, the reaction can be carried out using a pestle and mortar instead of ball milling as well, highlighting the operational simplicity of this approach for achieving challenging C(sp 3 )‐H activation under more sustainable conditions.