Tetrahydrofuran → 1-(2-Hydroxy-4,6-dimethoxyphenyl)-3-pyridin-4-ylpropane-1,3-dione

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Reaction Steps

To a solution of isonicotinic acid-2-acetyl-3,5-dimethoxyphenyl ester (2.72 g, 9.03 mmol) in anhydrous THF (50 mL) was added potassium tert-butoxide (1.21 g, 10.8 mmol) in small portions. The reaction mixture was stirred at room temperature for 24 hours. A sat. NH4Cl solution (20 mL) was added. The organic layer was separated and aqueous phase was extracted with ethyl acetate (100 mL). The combined organic phase were washed with water, brine and dried over anhydrous Na2SO4. Removal of solvent gave 1-(2-hydroxy-4,6-dimethoxyphenyl)-3-pyridin-4-yl-propane-1,3-dione (2.4 g, 88%). To a mixture of 1-(2-hydroxy-4,6-dimethoxyphenyl)-3-pyridin-4-yl-propane-1,3-dione (2.4 g, 7.96° mmol) acetic acid (10 mL) and conc. HCl (1 mL) was heated at 100° C. for 1 hours. The reaction mixture was cooled to room temperature, diluted with water, neutralized with a sat. aqueous NaHCO3 solution. The solid was filtered off and dissolved in CH2Cl2 (120 mL) and hydrogen chloride in ether (5 mL, 2.0M solution) was added. The formed solid was isolated by filtration, washed with 10% methanol in ether and ether to give 5,7-dimethoxy-2-(pyridin-4-yl))-4H-chromen-4-one hydrochloride (0.335 g, 13%) as a yellow solid; MS (ES) m/z: 283.94 (M); MP 234-235° C.

Provenance & Evidence