Solvent-free Darzens condensation of 3-chlorooxindoles with aryl aldehydes for diastereoselective construction of spiro-epoxyoxindoles by grinding

A highly efficient, diastereoselective strategy for the synthesis of aryl-substituted spiro-epoxyoxindole derivatives by a Darzens-type reaction of alpha-chlorooxindoles with aryl aldehydes in the presence of bases under solvent-free grinding conditions has been developed. The process features with easy work-up, mild reaction condition, high to excellent diastereoselectivitie and yields as well as environmental compatibility.