To a stirred 30 mL microwave vial was added a solution of aryl or heteroaryl halides (Br, I) (0.5 mmol) and monoethyl malonate potassium salt (0.75 mmol) in THF (10 mL). Pd(OAc)2 (5 mol%), Xantphos (5 mol%), MgCl2 (0.75 mmol), Et3N (0.75 mmol), imidazole (1 mmol), and Co2(CO)8 (0.15 mmol) were then added sequentially. The vials were immediately sealed and subjected to microwave irradiation at 90 °C for 30 min. After completion of the reaction, the mixture was concentrated and diluted with ethyl acetate and water. The organic layer (ethyl acetate layer) was separated, dried over anhydrous sodium sulfate and then concentrated. The crude product was purified by column chromatography to afford the target compound ethyl 4-trifluoromethylbenzoylacetate.
