620-80-4

141-97-9

100-52-7

620-80-4

To an anhydrous DMSO solution containing L-proline (30 mol%) was added benzaldehyde (1 eq.). The reaction mixture was stirred at room temperature for 8-10 minutes, followed by the slow addition of ethyl acetoacetate (1.2 eq.) at the same temperature. The reaction system was warmed up to 80 °C with continuous stirring for 6-8 hours. Upon completion of the reaction, ethyl acetate (10 mL) was added to the mixture and stirred for several minutes before quenching the reaction with cold water. The organic and aqueous phases were separated and the aqueous phase was extracted with ethyl acetate (3 x 20 mL). The organic phases were combined, washed with saturated saline and dried with anhydrous sodium sulfate. After concentration under reduced pressure to remove the solvent, the crude product was purified by column chromatography on silica gel (60-120 mesh), the eluent being a hexane solution of 5% ethyl acetate.