Ethoxalyl chloride → Ethyl 3-(3,5-dibromo-4-hydroxyphenyl)-1,2,4-oxadiazole-5-carboxylate
Reaktionsgleichung
Cl[C:2](=[O:8])[C:3]([O:5][CH2:6][CH3:7])=[O:4].[Br:9][C:10]1[CH:11]=[C:12]([CH:17]=[C:18]([Br:21])[C:19]=1[OH:20])[C:13](=[N:15]O)[NH2:14]>N1C=CC=CC=1>[Br:9][C:10]1[CH:11]=[C:12]([C:13]2[N:15]=[C:2]([C:3]([O:5][CH2:6][CH3:7])=[O:4])[O:8][N:14]=2)[CH:17]=[C:18]([Br:21])[C:19]=1[OH:20]Komponenten
4
Edukt 2
Produkt 1
Reagenzien, Katalysatoren, Lösungsmittel 1
Versuchsvorschrift
Ethyl 2-chloro-2-oxoacetate (12.3 g, 82 mmol) was added dropwise to a stirred solution of 3,5-dibromo-N′,4-dihydroxybenzimidamide (25.5 g, 82 mmol) in pyridine (120 mL) and the mixture was stirred at room temperature for 1 hour and then at 60° C. for 2 hours. The resulting suspension was poured onto water (1.5 L) and extracted with ethyl acetate (2×400 mL). The combined extracts were washed with saturated sodium chloride, dried (MgSO4) and evaporated in vacuo to give an oily solid that was purified by flash chromatography to give a colourless powder. Crystallisation from toluene (400 mL) gave the title compound (14.7 g, 46%) as colourless crystals. 1H NMR δ (ppm) (DMSO-d6): 1.14 (3 H, t), 4.49 (2 H, q), 8.14 (2 H, s), 10.93 (1 H, br s).