Grind-and-Heat: Solvent-free Catalytic C–H and C–X Functionalization Without a Ball Mill

This study describes an accessible approach to various solvent-free transition metal-catalyzed C–H and C–X functionalizations. Conditions from eight different Rh-, Ru-, Ir- and Pd-based mechanochemical reactions are adapted to proceed with generally high efficiency by substituting automated ball milling with pestle and mortar grinding and subsequent heating. This is a low-cost, operationally simple method that requires no specialized equipment and offers similar sustainability benefits. The reaction scope encompasses 10 heterocycle types, many pendant functional groups and is demonstrated on the late-stage modification of a variety of bioactive compounds.