Chloroacetone → 4-(2-Oxopropoxy)-2H-1-benzopyran-2-one

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To a solution of 4-hydroxycoumarin (1.62 g, 10 mmol) in acetone (20 ml) were added potassium carbonate (5.53 g, 40 mmol) and chloroacetone (1.38 g, 15 mmol). The resulting mixture was refluxed for 4 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 4-(2-Oxopropoxy)-2H-1-benzopyran-2-one (1a) (1.28 g, 55.1%) as a white needle crystal. mp: 163°-165° C.; IR(KBr) νmax : 1716, 1625; UV(CHCl3) λmax (log ε): 305 (3.83), 266 (4.05); 1H-NMR (CDCl3): δ2.36 (s, 3H, CH3), 4.77 (s, 2H, OCH2), 5.57 (s, 1H, 3-H), 7.28-7.36 (m, 2H, 6- and 8-H), 7.54-7.63 (m, 1H, 7-H), 7.88-7.94 (m, 1H, 5-H). Anal. Calcd for C12H10O4 : C, 66.05; H, 4.62. Found: C, 66.01; H, 4.64.

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