[OH:1][C:2]1[CH:3]=[C:4]([CH:10]=[CH:11][C:12]=1[O:13][CH3:14])[CH:5]=[CH:6][C:7]([OH:9])=[O:8].Br[CH2:16][CH2:17][CH2:18][CH2:19][CH3:20].C(=O)([O-])[O-].[K+].[K+]>CN(C=O)C>[CH3:14][O:13][C:12]1[CH:11]=[CH:10][C:4]([CH:5]=[CH:6][C:7]([O:9][CH2:16][CH2:17][CH2:18][CH2:19][CH3:20])=[O:8])=[CH:3][C:2]=1[O:1][CH2:11][CH2:12][CH2:2][CH2:3][CH3:4]3-Hydroxy-4-methoxycinnamic acid (9.7 g, 0.050 mol, 1.0 eq) was dissolved in DMF (90 ml). 1-Bromopentane (22.7 g, 0.150 mol, 3.0 eq) and anhydrous potassium carbonate (41.5 g, 0.30 mol, 6.0 eq) were successively added to this solution, and the mixture was stirred under heating at 90° C. for 3 hours. This reaction mixture was cooled to room temperature, and anhydrous potassium carbonate was filtered off. Water (200 ml) was added to the filtrate, and the mixture was exracted twice with ethyl acetate (200 ml). The organic layers were combined, washed with saturated brine (300 ml) and dried over anhydrous sodium sulfate. The drying agent was filtered off, and the filtrate was concentrated under reduced pressure. The obtained residue was purified by column chromatography (n-hexane/ethyl acetate=15/1-10/1) to give pentyl 4-methoxy-3-pentyloxycinnamate (18.2 g, 100%) as a colorless oil.
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