Sodium cyanoborohydride → 4-Methyl-3-oxo-1,2,3,4-tetrahydro-quinoxalin-2-yl-acetic acid ethyl ester
Reaktionsgleichung
[CH2:1]([O:3][C:4](=[O:18])[CH:5]=[C:6]1[C:15](=[O:16])[N:14]([CH3:17])[C:13]2[C:8](=[CH:9][CH:10]=[CH:11][CH:12]=2)[NH:7]1)[CH3:2].C([BH3-])#N.[Na+]>CO.CC(O)=O>[CH2:1]([O:3][C:4](=[O:18])[CH2:5][CH:6]1[C:15](=[O:16])[N:14]([CH3:17])[C:13]2[C:8](=[CH:9][CH:10]=[CH:11][CH:12]=2)[NH:7]1)[CH3:2]Komponenten
4
Edukt 2
Produkt 1
Reagenzien, Katalysatoren, Lösungsmittel 1
Versuchsvorschrift
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).