Ethyl bromopyruvate → Ethyl 2-aminothiazole-4-carboxylate

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Reaction Steps

2-Amino-thiazole-4-carboxylic acid ethyl ester was prepared by a modification to the procedure of Kumar, R.; Rai, D. et al., Heterocyclic Communications 2002, 8, 521-530. Thiourea (18.45 g, 240 mmol) was suspended in absolute ethanol (192 mL) and to this was added ethyl bromopyruvate (52 g, 240 mmol) over 5 minutes. The solution was stirred at room temperature overnight and then concentrated in vacuo and taken into water (400 mL) and 6 N aqueous hydrochloric acid (44 mL). The aqueous mixture was washed with ethyl acetate (2×) and back extracted with water (50 mL). The combined aqueous solution was adjusted to pH=10 with sodium hydroxide and extracted with 10% dichloromethane in tetrahydrofuran (3×200 mL). The combined organic extracts were dried over sodium sulfate, concentrated and dried in vacuum. The pale yellow solid was taken into dichloromethane (25 mL) and to the slurry was added hexanes (300 mL). The mixture was vigorously stirred for 15 minutes then filtered on a 9 cm funnel and dried in vacuum to give 2-amino-thiazole-4-carboxylic acid ethyl ester as an off white solid (38 g, 92%).

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