2-((3-Ethoxy-2-(ethoxycarbonyl)-3-oxoprop-1-enyl)amino)-4-methylthiophene-3-carboxylic acid → Ethyl 3-methyl-4-oxo-4,7-dihydrothieno[2,3-b]pyridine-5-carboxylate
Reaktionsgleichung
C(OC(=O)[C:5]([C:17]([O:19][CH2:20][CH3:21])=[O:18])=[CH:6][NH:7][C:8]1[S:9][CH:10]=[C:11]([CH3:16])[C:12]=1[C:13]([OH:15])=O)C>C1(OC2C=CC=CC=2)C=CC=CC=1>[OH:15][C:13]1[C:5]([C:17]([O:19][CH2:20][CH3:21])=[O:18])=[CH:6][N:7]=[C:8]2[S:9][CH:10]=[C:11]([CH3:16])[C:12]=12Komponenten
3
Versuchsvorschrift
In a flask equipped with a Dean-Stark trap, a mixture of 2-((3-ethoxy-2-(ethoxycarbonyl)-3-oxoprop-1-enyl)amino)-4-methylthiophene-3-carboxylic acid (Preparation 25, 4.58 g) and phenyl ether (50 mL) is degassed by freeze-pump-thaw method and then heated to reflux. After approximately 30 min, the reaction mixture is allowed to cool to room temperature. The crude mixture is purified by column chromatography (CH2Cl2; CH2Cl2/methanol, 100/1) to afford 1.95 g of the title compound as a yellow solid. Physical characteristics. M.p. 189-192° C.; 1HNMR (400 MHz, CF3CO2D) δ 11.65, 9.10, 7.31, 4.66, 2.76, 1.53; MS (ESI−) m/z 236 (M—H). Anal. Found: C, 55.66; H, 4.67; N, 5.85; S, 13.40.