4-Bromo-2-methylbut-1-ene → 2-Methoxy-1-[2,4,6-trihydroxy-3,5-di(3-methyl-2-buten-1-yl)phenyl]ethanone

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Reaction Steps

2-methoxy-1-(2,4,6-trihydroxyphenyl)ethanone (8.3 g, 42 mmol) was dissolved in a 5% potassium hydroxide aqueous solution (84 ml). After the reaction mixture was cooled below 0° C., Isopentenyl bromide (12.48 g, 84 mmol) was slowly added dropwise to within 30 minutes. The reaction mixture was stirred at room temperature (RT) for 2 hours, then poured into an ice water and acidified to pH 2. The reaction mixture was extracted with ethyl acetate. The extract was collected and dried over anhydrous sodium sulfate, followed by removing solvent. The desired compound was obtained by purifying the residue by silica gel column chromatography (dichloromethane as eluent) (5.7 g, yield 41%). 1H NMR (400 MHz, DMSO-d6): δ=11.44 (s, 2H), 9.24 (s, 1H), 5.00 (t, 2H, J=6.8 Hz), 4.63 (s, 2H,), 3.31 (s, 3H), 3.22 (d, 4H, J=6.8 Hz), 1.67 (s, 6H), 1.58 (s, 6H).

Provenance & Evidence