反应详情

4-Amino-3-ethylbenzonitrile (2.00 g, 13.7 mmol) was added to a solution of 3,4-diethoxy-3-cyclobutene-1,2-dione (2.30 g, 13.5 mmol) in acetonitrile (5 mL). After refluxing the mixture for 24 h a second portion of 3,4-diethoxy-3-cyclobutene-1,2-dione (1.15 g, 6.76 mmol) was added and heating was continued for an additional 24 h. The reaction mixture was diluted with ethyl acetate (45 mL), stirred vigorously and filtered free of undissolved solid. The filtrate was concentrated and the resulting residue was purified by chromatographed (CH3OH/CH2Cl2) and trituration with ether to afford 0.86 g (24%) of product as a light yellow solid: 1H NMR (DMSO-d6): δ 10.57 (s, 1H), 7.77-7.66 (m, 2H), 7.31 (d, 1H), 4.71 (q, 2H), 2.73 (q, 2H), 1.37 (t, 3H), 1.13 (t, 3H).

1. additionwas added
2. temperatureheating
3. filtrationfiltered free of undissolved solid
4. concentrationThe filtrate was concentrated
5. customthe resulting residue was purified
6. customby chromatographed (CH3OH/CH2Cl2) and trituration with ether