A mixture of 0.30 g of ethyl 2,2-bis(fluoromethyl)-6-iodo-2H-1-benzopyran-4-carboxylate, 3.50 g of nonafluoro-butyl iodide, 0.30 g of copper powder, 0.32 g of cuprous iodide and 3 ml of hexamethylphosphoric triamide was stirred with heating at 70° C. for 22 hours, added another 1.75 g of nonafluorobutyl iodide, and stirred with heating at 150° C. for 5 hours. A mixture of 2N HCl and ethyl acetate was added to the reaction mixture, and insoluble materials were separated off using a celite. An organic layer was taken up, and an aqueous layer was extracted with ethyl acetate. The organic layers were combined, washed with saturated sodium chloride solution, dried over sodium sulfate, and concentrated in vacuo. The resultant residue was purified with silica gel column chromatography (developing solution, methylene chloride:hexane=5:1) to obtain 0.19 g of ethyl 6-nonafluorobutyl-2,2-bis(fluoromethyl)-2H-1-benzopyran-4-carboxylate as an oil.
