反应详情

4-Methyl-3-oxo-3,4-dihydro-1H-quinoxalin-2-ylidene-acetic acid ethyl ester (1.1 g, 4.47 mmol) was suspended in 25 mL of MeOH/HOAc (2:1) at rt and sodium cyanoborohydride was added portionwise (281 mg, 4.47 mmol). The mixture became clear after five minutes and was continuously stirred at rt for 2 hours. The solvent was removed under reduced pressure. The crude residue was mixed with water (50 mL) and extracted with EtOAc (3×40 mL). The organic layers were combined, washed with water, brine and dried over MgSO4. After removal of the solvent, a pale brown oil was obtained as the desired pure product: 1H NMR (CDCl3) δ=6.97–6.94 (m, 3H), 6.74 (d, J=9.0 Hz, 1H), 4.28 (dd, J=3.0, 9.0 Hz, 1H), 4.23 (q, J=9.0 Hz, 2H), 3.37 (s, 3H), 3.11 (dd, J=3.0, 18.0 Hz, 1H), 2.68 (dd, J=9.0, 19.0 Hz, 1H), 1.28 (t, J=9.0 Hz, 3H).

1. customThe solvent was removed under reduced pressure
2. additionThe crude residue was mixed with water (50 mL)
3. extractionextracted with EtOAc (3×40 mL)
4. washwashed with water, brine
5. dry with materialdried over MgSO4
6. customAfter removal of the solvent
7. customa pale brown oil was obtained as the desired pure product