Methyl vinyl ketone → 6,8-Dimethyl-3-Acetyl-2H-Chromene

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Reaction Steps

1.50 g (10 mmol) of 2-hydroxy-3,5-dimethylbenzaldehyde together with 0.66 g (10 mmol) of 3-oxo-1-butene are added at room temperature to a suspension of 0.14 g (1 mmol) of potassium carbonate in 50 ml of 2-butanone. The mixture is brought to reflux with stirring and this temperature is maintained for 90 minutes. The reaction medium is evaporated on a water bath under vacuum, and the residue is taken up with 100 ml of water and extracted 3 times with 75 ml of diethyl ether. The organic phases are combined, washed to neutrality with saturated aqueous sodium chloride solution, dried over sodium sulfate, filtered and evaporated on a water bath under vacuum, and chromatographed on a column of silica (70-230 mesh), eluting with dichloromethane.

Provenance & Evidence