Sulfuric Acid → 6-Chloro-7-hydroxy-2,3-dihydro-4H-1-benzopyran-4-one

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Reaction Steps

3-chloro-1-(5-chloro-2,4-dihydroxyphenyl)propan-1-one (140 g, 596 mmol) was dissolved in a 2M aqueous NaOH solution (2085 ml) at 0° C. then allowed to warm up to ambient temperature over the next 2 hours. The reaction was acidified by the addition of 6M H2SO4 to a pH of ˜2. The resulting solids were removed by filtration and dried under high vacuum. The resulting solid was dissolved in THF (600 ml) and washed with water. The organic layer and was dried over magnesium sulfate, filtered, and concentrated. The resulting solid was treated with a minimal amount of diethyl ether and sonicated until a homogeneous suspension resulted. The resulting solid was collected by filtration to give the desired compound (85.7 g, 73%).

Provenance & Evidence