Potassium Carbonate → 6-phenoxy-2-methyl-2H-1-benzopyran-3-carboxaldehyde

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Reaction Steps

The starting material is prepared as follows: A mixture of 5-phenoxysalicylaldehyde (6.52 g, 30.4 mmol), crotonaldehyde (3.2 g, 45.7 mmol) and potassium carbonate (8.41 g, 60.9 mmol) in 100 ml of 1,4-dioxane is heated at reflux for 2 hours. The mixture is cooled, diluted with water, and extracted three times with dichloromethane. The combined organic layers are dried (MgSO4) and evaporated. Purification by flash chromatography (silica gel, 7% ethyl acetate/hexane) yields 6-phenoxy-2-methyl-2H-1-benzopyran-3-carboxaldehyde which is converted to 6-phenoxy-2-methyl-3-(N-hydroxyaminomethyl)-2H-1-benzopyran as described above.

Provenance & Evidence