1-Butanol → 7-(diethylamino)-3-nitro-2H-chromen-2-one

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A mixture containing n-butanol (20 mL), 4-diethylamino salicylaldehyde (1.4 g, 7.2 mmol), ethyl nitroacetate (0.8 mL, 7.2 mmol), molecular sieves 4 Å (100 mg), piperidine (0.1 mL) and acetic acid (0.2 mL) was refluxed for a period of 24 h. Upon cooling to room temperature, a bright yellow solid formed, which was collected and dissolved in DMF (15 mL) at 80° C. It was filtered again to remove the molecular sieves. The filtrate, upon addition to 100 ml of ice-cold water, yielded 3-nitro-7-diethylamino coumarin as a bright yellow solid: 1.40 g, 73%. A small amount of this compound was recrystallized from DMF to give an analytical sample; mp 193-195° C. 1H-NMR (CDCl3, 300 MHz) δ 1.27 (t, J=7.14 Hz, 6H), 3.48 (q, J=7.86 Hz, 4H), 6.50 (s, 1H), 6.70 (d, J=6.71 Hz, 1H), 7.42 (d, J=7.42 Hz, 2H), 8.72 (s, 1H). HRMS m/e calculated for MH+ C13H14N2O4 263.1041; found 263.1032.

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