Solvent-free synthesis of unsaturated amino esters in a ball-mill

The ball-milling technique was used under solvent-free conditions to perform a Horner–Wadsworth–Emmons reaction in the presence of a mild carbonate base. Starting from a phosphonate-substituted glycine, this method gave access to Boc-protected unsaturated amino esters in excellent yield and selectivity in many cases. The scope of the reaction was delineated.