Iodoethane → 6,8-Difluoro-7-ethoxy-4-methylcoumarin

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Reaction Steps

A solution of Compound 5 (0.10 g, 0.47 mmol) and ethyl iodide (112 μL, 1.4 mmol) in acetone (10 mL) is stirred at reflux with potassium carbonate (207 mg, 1.5 mmol) for 72 hours, during which additional ethyl iodide (2×200 μL) is added at 24 and 48 hours. After cooling, the reaction mixture is filtered and the filtrate is concentrated to a colorless solid. This solid is purified by preparative TLC (silica gel, 1000 μm plate, eluting with ethyl acetate/hexanes 1:1) to give 50 mg of nonfluorescent Compound 7 as a colorless solid. UV-vis (MeCN): 298 nm, ε=7,770 cm-1M-1 ; 279 nm, ε=11,080 cm-1 M-1. Rf (ethyl acetate/hexanes 3:2) 0.75. 1H NMR (CDCl3) 7.10 (dd, 1H), 6.28 (s, 1H), 4.38 (q, 2H), 2.39 (s, 3H), 1.42 (t, 3H). 19F NMR (CDCl3) 132.2 (t, 1F), 146.9 (d, 1F). Anal. calcd for C12H10O3F2 : C, 60.00; H, 4.20; N, 0.00; Found: C, 59.98; H, 4.27; N, 0.01.

Provenance & Evidence