N-bromobutanimide → Ethyl 2-phenylthiazole-5-carboxylate
Reaktionsgleichung
BrN1[C:6](=[O:7])[CH2:5][CH2:4]C1=O.[C:9]([NH2:17])(=[S:16])[C:10]1[CH:15]=[CH:14][CH:13]=[CH:12][CH:11]=1.O1CCO[CH2:20][CH2:19]1.[OH2:24]>>[C:10]1([C:9]2[S:16][C:5]([C:6]([O:7][CH2:19][CH3:20])=[O:24])=[CH:4][N:17]=2)[CH:15]=[CH:14][CH:13]=[CH:12][CH:11]=1Komponenten
4
Reaktionsbedingungen
- Temperatur
- -10 °C
Versuchsvorschrift
Ethyl-3-ethoxyacryalate (4.0 g, 27.7 mmol) was dissolved in dioxane-H2O (30 ml, 1:1 v/v) and cooled to −10° C. N-Bromosuccinimide (5.43 g, 30.5 mmol) was added to this solution and the reaction mixture was allowed to warm up to room temperature and further stirred for 1 h. Thiobenzamide (3.8 g, 27.7 mmol) was then added and the reaction mixture was further heated to 80° C. for 1 h. The reaction mixture was then cooled to room temperature and quenched with aqueous ammonia solution. The organic product was extracted with EtOAc and combined extracts were washed with H2O and brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The crude product was purified by column chromatography (silica gel 60-120 mesh, eluent 5-10% EtOAc in petroleum ether) to afford ethyl 2-phenylthiazole-5-carboxylate (1.1 g, yield 17%) as a yellow solid. 1H NMR (300 MHz, CDCl3) δ 8.43 (s, 1H), 8.01-7.98 (m, 2H), 7.48-7.48 (m, 3H), 4.44-4.37 (q, J=7.2 Hz, 2H), 1.44-1.39 (t, J=7.2 Hz, 3H). MS (ESI) m/z: Calculated for C12H11NO2S: 233.05. found: 234.0 (M+H)+.