Phenacyl bromide → 7-(2-oxo-2-phenylethoxy)-2H-chromen-2-one

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To a solution of 7-hydroxycoumarin (1.62 g, 10 mmol) in acetone (60 ml) were added 2-bromoacetophenone (1.99 g, 10 mmol) and potassium carbonate (5.53 g, 40 mmol). The mixture was refluxed for 3 h. (monitored by TLC). Evaporation of the solvent gave a residue which was poured into ice water (50 ml). The resulting solid was collected and crystallized from ethyl acetate to afford 7-(2-oxo-2-phenylethoxy)-2H-1-benzopyran-2-one (4a) (1.53 g, 73.1%) as a needle crystal. mp: 163°-165° C.; IR(KBr) νmax : 1728, 1702, 1627; UV(CHCl3) λmax (log ε): 320 (4.16), 249 (4.13); 1H-NMR (CDCl3): δ5.39 (s, 2H, OCH2), 6.27 (d, 1H, 3-H), 6.80 (d, 1H, 8-H), 6.93 (dd, 1H, 6-H), 7.40 (d, 1H, 5-H), 7.49-7.68 (m, 4H, 4-H and aromatic H). Anal Calcd for C17H12O4 : C, 72.85; H, 4.32. Found: C, 72.98; H, 4.35.

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