Add Hans ester Et-HE (0.8mmol) to the reaction tube equipped with a magnetic stir bar, Ru(bpy)3Cl2?¤6H2O (0.004 mmol) and p-cresol (0.08 mmol). Cover the reaction tube and change the nitrogen three times, Use a micro syringe to inject 4-cyanostyrene (0.4mmol), Ethyl diazoacetate (0.8 mmol) and anhydrous dichloromethane (2.0 mL, 0.2M). Then the reaction tube was placed about 15 cm away from the 50W blue light source for illumination and stirring. React at 25??C for 12 hours until the diazonium consumption is complete (monitored by thin layer chromatography). After the solvent was removed by rotary evaporation under reduced pressure, a crude product was obtained. The crude product was purified by silica gel column chromatography to obtain the corresponding product (petroleum ether: ethyl acetate=25:1), the total yield: 86%.
