[CH2:1]([O:3][C:4]1[CH:9]=[CH:8][C:7]([C:10](=[O:12])[CH3:11])=[C:6]([OH:13])[CH:5]=1)[CH3:2].[C:14](OCC)(=O)[C:15]([O:17][CH2:18][CH3:19])=[O:16].[O-]CC.[Na+].Cl>C(O)C.O.C(OCC)C>[CH2:1]([O:3][C:4]1[CH:5]=[C:6]2[C:7]([C:10](=[O:12])[CH:11]=[C:14]([C:15]([O:17][CH2:18][CH3:19])=[O:16])[O:13]2)=[CH:8][CH:9]=1)[CH3:2]
To a solution of 1-(4-ethoxy-2-hydroxyphenyl)ethanone (Aldrich, 5.0 g, 27.7 mmol) and diethyl oxalate (8.3 mL, 61 mmol) in ethanol (50 mL) was added sodium ethoxide (21% in EtOH, 31 mL, 83 mmol) and the mixture was refluxed for 1.5 hours. The mixture was cooled to ambient temperature, diethyl ether (150 mL), water (150 mL) and 12N hydrochloric acid (7 mL) were added. The separated organic layer was washed with brine, dried over anhydrous sodium sulfate, filtered and was concentrated under reduced pressure to afford ethyl 7-ethoxy-4-oxo-4H-chromene-2-carboxylate. The intermediate was dissolved in acetic acid (70 mL) and 12N hydrochloric acid (8.5 mL), heated to reflux for 2 hours, and cooled to ambient temperature. Water (300 mL) was added and the solids were collected by filtration, rinsed with water, and freeze-dried to afford the title compound. 1H NMR (300 MHz, DMSO-d6) δ ppm 1.38 (t, 3H), 4.20 (q, 2H), 6.84 (s, 1H), 7.08 (dd, 1H), 7.19 (d, 1H), 7.92 (d, 1H). MS (APCI) m/z 235.04 (M+H)1.
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