4-Hydroxybenzoic Acid → Methyl 3,5-diallyloxy-2-ethyl-6-(4-hydroxybenzoyl)phenylacetate

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Reaction Steps

Methyl 3,5-diallyloxy-2-ethylphenylacetate (1.0 g, 3.3 mmol) obtained in Example 5, Step 3 was dissolved in trifluoroacetic acid (9.0 mL), and 4-hydroxybenzoic acid (1.4 g, 10 mmol) and trifluoroacetic anhydride (1.2 mL) were added thereto, followed by stirring at room temperature for 20 hours. To the mixture were further added 4-hydroxybenzoic acid (0.92 g, 6.6 mmol) and trifluoroacetic anhydride (1.4 mL), followed by stirring for 6 hours. The reaction mixture was added dropwise to a saturated aqueous solution of sodium hydrogencarbonate (0.10 L), and the resulting mixture was extracted with ethyl acetate (50 mL×4). The organic layer was dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The resulting residue was dissolved in a 7 mol/L solution of ammonia in methanol (100 mL), followed by stirring at room temperature for 1 day. After the reaction mixture was concentrated under reduced pressure, 3 mol/L hydrochloric acid (40 mL) was added thereto, followed by extraction with ethyl acetate (50 mL×3). The organic layer was washed with water, dried over anhydrous sodium sulfate, and then concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (ethyl acetate/hexane=1/10-1/2) to obtain methyl 3,5-diallyloxy-2-ethyl-6-(4-hydroxybenzoyl)phenylacetate (0.84 g, 57%).

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