[H-].[Na+].[C:3](=O)(OCC)[O:4]CC.F[C:12]1[CH:13]=[CH:14][C:15]([OH:21])=[C:16]([C:18](=[O:20])[CH3:19])[CH:17]=1.[OH-].[Na+]>C1C=CC=CC=1>[OH:20][C:18]1[C:16]2[C:15](=[CH:14][CH:13]=[CH:12][CH:17]=2)[O:21][C:3](=[O:4])[CH:19]=1To a stirred suspension of sodium hydride (Aldrich, 60% dispersion in mineral oil) (1.2 g, 30.0 mmol) and diethyl carbonate (Aldrich) (5.9 g, 50 mmol) in anhydrous benzene (Aldrich) (100 mL) under a dry nitrogen atmosphere was added dropwise a solution of 5'-fluoro-2'-hydroxy-acetophenone (Aldrich) (1.54 g, 10 mmol) in anhydrous benzene. The mixture was then refluxed under a nitrogen atmosphere overnight. The reaction mixture was cooled and 50 mL 1N NaOH was added. The mixture was stirred at room temperature for 1 hour. The aqueous layer was separated and washed with ether (100 mL×2). The dark solution was acidified to pH 2 with 6N HCl. The white precipitate was collected by filtration, washed with water and dried to afford product (4) (4-hydroxy-6-fluoro-coumarin) as an off-white solid (1.38 g, 7.66 mmol, 77%). 300-MHz 1H-NMR (CDCl3) δ 5.79 (s,1H), 7.25-7.28 (m,2H), 7.52 (d,1H). Mass/EI: 179 (M-H).
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