Water → 2-Methyl-1-[2,4,6-trihydroxy-3-(3-methyl-2-buten-1-yl)phenyl]-1-propanone

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Reaction Steps

Under an atmosphere of nitrogen, 981 mg (5.00 mmol) of (2,4,6-trihydroxyphenyl) (2-propyl) ketone (4) was dissolved in 10.0 ml of dioxane, cooled with cold water at about 10° C., and stirred. Into the stirred solution, 554 ml (639 mg, 4.50 mmol, 0.900 equivalent) of boron trifluorideether complex was added by the use of a microsyringe. The resultant mixture was further stirred for 15 minutes and then a dioxane (9 ml) solution of 861 mg of 3-methyl-2-butenol was slowly added dropwise. After four hours, the reaction solution was poured into 100 ml of ether. The ether layer was washed sequentially with a saturated aqueous sodium hydrogen carbonate solution and saturated brine and dried over sodium sulfate. The produced solution was distilled under a reduced pressure to remove the solvent and obtain 1.76 g of a crude product in the form of a red viscous oily substance. The crude product was treated by silica gel column chromatography (50 g of Wako Gel C-300, and eluted sequentially with 200 ml each of petroleum ether:ether at varying ratios=9:1, 7:3, and 5:5) to isolate 417 mg of {3-(3-methyl-2-butenyl)-2,4,6-trihydroxyphenyl} (2-propyl) ketone (23) and 338 mg of 2,2-bis(3-methyl-2-butenyl)-3,5-dihydroxy-6-(2-methyl-1-oxopropyl) cyclohexa-3,5-dienone (13).

Provenance & Evidence