反应详情

2.16 ml (10 mmol) of 3,4-dibutoxy-3-cyclobutene-1,2-dione (2b) was dissolved in 20 ml of anhydrous benzene, and 660 mg (10 mmol) of malonodinitrile was added under stirring. Then, 1.65 ml (12 mmol) of triethylamine was added dropwise for 5 min followed by 10 ml of anhydrous benzene. The obtained emulsion is stirred for 30 min at room temperature. The solvent is removed using a rotary evaporator. The yellow oiled residue is treated three times with ether to give crude product 2d (1.8 g, 56%), 1H-NMR (DMSO-d6): δ 10.15–9.55 (1H, broad s, NH+), 4.59 (2H, t, 6.7 Hz, OCH2), 3.07 (6H, q 7.4, 14.5 Hz, N(CH2CH3)3), 1.77–1.58 (2H, m, CH2), 1.48–1.26 (2H, m, CH2), 1.18 (9H, t, 7.3 Hz, N(CH2CH3)3), 0.90 (3H, t, 7.4 Hz, CH3).

1. stirringThe obtained emulsion is stirred for 30 min at room temperature
2. customThe solvent is removed
3. customa rotary evaporator
4. additionThe yellow oiled residue is treated three times with ether