反应详情

4-Aminobenzonitrile (17.58 g, 149 mmol) was added to a solution of 3,4-diethoxy-3-cyclobutene-1,2-dione (25.31 g, 149 mmol) in absolute ethanol (450 mL). The mixture was heated at reflux overnight and the resulting suspension filtered hot to remove a small amount of a dirty yellow solid (discarded). The filtrate was gradually concentrated to afford several crops of 4-(3,4-dioxo-2-ethoxy-cyclobut-1-enylamino)benzonitrile, as a bright yellow solid, which were collected by filtration and combined. Yield: 29.11 g (81%): 1H NMR (DMSO-d6): δ11.07 (s, 1H), 7.81 (d, 2H), 7.56 (d, 2H), 4.79 (q, 2H), 1.46 (t, 3H).

1. temperatureThe mixture was heated
2. temperatureat reflux overnight
3. filtrationthe resulting suspension filtered hot
4. customto remove a small amount of a dirty yellow solid (discarded)
5. concentrationThe filtrate was gradually concentrated