Ethyl 2-aminothiazole-4-carboxylate (100 g, 581 mmol) and copper(II) bromide (195 g, 871 mmol) were dissolved in acetonitrile (1000 ml) at 0 °C. Subsequently, tert-butyl nitrite (104 ml, 871 mmol) was added slowly and dropwise. The reaction mixture was gradually warmed to room temperature and stirred continuously for 12 hours. After completion of the reaction, the reaction mixture was diluted with a mixture of ethyl acetate (1000 ml) and water (3000 ml) and the pH was adjusted to 2 with 1 N hydrochloric acid.The organic and aqueous layers were separated, and the aqueous layer was extracted three times with ethyl acetate (500 ml). All organic layers were combined, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The crude product was purified by recrystallization from hexane to give pure ethyl 2-bromothiazole-4-carboxylate (115 g, 84% yield). The product was confirmed by 1H-NMR (400 MHz, DMSO-d6): δ 8.52 (s, 1H), 4.29 (q, J=7.1 Hz, 2H), 1.29 (t, J=7.1 Hz, 3H). Mass spectral analysis showed m/z 235.90 [M+1].
