N(OC(C)(C)C)=O.N[C:9]1[S:10][C:11]([CH3:18])=[C:12]([C:14]([O:16][CH3:17])=[O:15])[N:13]=1>O1CCOCC1>[CH3:18][C:11]1[S:10][CH:9]=[N:13][C:12]=1[C:14]([O:16][CH3:17])=[O:15]To a solution of tert-butyl nitrite (24 mL, 202 mmol) in 1,4-dioxane (180 mL) was added a mixture of methyl 2-amino-5-methyl-1,3-thiazole-4-carboxylate (6.83 g, 40.0 mmol) in 1,4-dioxane (70 mL). The solution was stirred at 60° C. for 1 hour. After cooling to room temperature, the solvent was evaporated. The crude oil was purified by flash chromatography (0-20% EtOAc/hexanes), affording methyl 5-methyl-1,3-thiazole-4-carboxylate (3.95 g, 63%). The product was used for the next step without any further purification.
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