[CH:1]1([O:6][C:7]2[CH:8]=[C:9]([CH:12]=[CH:13][C:14]=2[OH:15])[CH:10]=[O:11])[CH2:5][CH2:4][CH2:3][CH2:2]1.C(=O)([O-])[O-].[K+].[K+].[I-].[K+].[F:24][CH:25]([F:27])Cl>CN(C)C=O>[CH:1]1([O:6][C:7]2[CH:8]=[C:9]([CH:12]=[CH:13][C:14]=2[O:15][CH:25]([F:27])[F:24])[CH:10]=[O:11])[CH2:2][CH2:3][CH2:4][CH2:5]1A solution of 3-cyclopentyloxy-4-hydroxybenzaldehyde (5.1 g) in dimethylformamide (50 mL) is treated with potassium carbonate (4.83 g) and potassium iodide (1.2 g) and the solution is heated at 70-75° C. whilst difluorochloromethane is bubbled though it at a slow rate, during 5 hours. Water (100 mL) is added and the mixture is extracted with ethyl acetate (2×100 mL). The combined organic extracts are dried over magnesium sulfate and concentrated to give a brown oil. The oil is subjected to flash chromatography, eluting with a mixture of diethyl ether and pentane (1:4 v/v), to give 3-cyclopentyloxy-4-difluoromethoxybenzaldehyde, in the form of a pale yellow oil (4.7 g). [NMR (CDCl3): 9.92(s,1H); 7.5-7.24(m,3H); 6.34-5.96(t,1H); 4.9(m,1H); 2.0-1.6(m,8H)].
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