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Preparation of 2,4dimethoxy4'-prop-2-enyloxychalcone ##STR30## 0.88 g of 4-allyloxyacetophenone and 0.42 g of 2,4-dimethoxybenzaldehyde were dissolved in 3.5 ml of ethanol, and to the solution was added ethanol saturated with 3.5 ml of hydrogen chloride. The mixture was left at room temperature for 30 min during which time it turned heavily red. The solution was concentrated in vacuo and the residue chromatographed (column chromatography over silica gel 60 (Merck 0.0630-0.200 mm, 100 g), eluent toluene and toluene to which increasing amounts of ethyl acetate were added) to give 500 mg of 4-methoxyacetophenone and 471 mg of 2,4-dimethoxy-4'-prop-2-enyloxychone. The chalcone was recrystallized from petroleum ether-ethyl acetate to give 370 mg of slightly yellow crystals. For data, see Example 2.24.

1. concentrationThe solution was concentrated in vacuo
2. customthe residue chromatographed
3. temperature(column chromatography over silica gel 60 (Merck 0.0630-0.200 mm, 100 g), eluent toluene and toluene to which increasing amounts of ethyl acetate were added)