Investigation of Mechanochemical Sonogashira Couplings─From Batch Solution to Continuous Reactive Extrusion through Ball-Milling Optimization

Solvents used to run chemical reactions on a process scale are the largest contributors to hazardous waste in active pharmaceutical ingredient (API) process manufacturing. Frequently, the solvents providing optimal reaction performance are toxic and environmentally damaging. The rapid emergence of mechanochemistry as a practical tool for organic synthesis has piqued the interest of process chemists as a potential method that could reduce solvent use and perform organic transformations in a safer and environmentally friendly manner. Reactive extrusion has become a viable option for chemists to perform multigram-scale reactions in a continuous manner. Herein, we demonstrate the use of small-scale ball-milling experiments as a screening and optimizing system to allow translation of a Sonogashira coupling reaction from small-scale to twin-screw extrusion for implementation at a larger scale.