Ethyl 4-bromo-2-nitro-6-(trifluoromethyl)phenyl(2-chlorobenzyl)carbamate (620.3 mg) was dissolved in N,N-dimethylformamide (30 ml), and to the solution were added zinc cyanide (302.4 mg) and tetrakis(triphenylphosphine)palladium(0) (1.116 g). The mixture was heated at 60° C. and stirred for 7 hours. After allowing to cool, to the reaction mixture was added 1N hydrochloric acid, and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated brine, dried over anhydrous magnesium sulfate, and concentrated in vacuo. The resultant residue was purified by silica gel column (100 g, hexane:ethyl acetate=3:1) to give the title compound (322.6 mg, 59%).
