反应详情

A solution of 2-bromo-4-methoxy aniline (6.02 g, 29.8 mmol) in 125 mL anhydrous methanol was treated with dimethyl acetylenedicarboxylate (3.70 mL, 30.2 mmol) and the solution was heated at reflux under nitrogen for 8 hours. The reaction mixture was cooled, concentrated, and redissolved in hot methanol. Yellow crystals were obtained by filtration (6.93 g, 68%). A second crop of crystals was obtained from ethanol (0.942 g, 9%). The filtrates were combined and purified by flash chromatography on silica gel using 4:1 hexanes:ethyl acetate to afford an additional 1.63 g (16%) for a total yield of 93%. 1H NMR (300 MHz, DMSO, d6) δ 9.60 (s, 1 H, NH), 7.26 (d, 1 H, Jm=2.7 Hz, ArH3), 6.93 (dd, 1 H, Jo=8.7, Jm=2.7 Hz, ArH5), 6.87 (d, 1 H, Jo=8.7 Hz, ArH6), 5.34 (s, 1 H, C═CH), 3.76 (s, 3 H, OCH3), 3.68 (s, 3 H, CHCO2CH3), 3.66 (s, 3 H, CNCO2CH3); Mass Spec.: calc. for [C13H14BrNO5+H]+ Theor. m/z=344, 346; Obs. 344, 346.

1. temperaturethe solution was heated
2. temperatureat reflux under nitrogen for 8 hours
3. temperatureThe reaction mixture was cooled
4. concentrationconcentrated
5. dissolutionredissolved in hot methanol
6. customYellow crystals were obtained by filtration (6.93 g, 68%)
7. custompurified by flash chromatography on silica gel using 4:1 hexanes
8. customethyl acetate to afford an additional 1.63 g (16%) for a total yield of 93%