118452-04-3

24424-99-5

850429-62-8

General procedure for the synthesis of methyl 2-(Boc-amino)thiazole-4-carboxylate from methyl 2-aminothiazole-4-carboxylate and di-tert-butyl dicarbonate: to a 1:1 dichloromethane/tetrahydrofuran (200mL) solution containing methyl 2-aminothiazole-4-carboxylate (10.0g, 63.22mmol, prepared as described in Example 3, Step 2), was added di-tert-butyl dicarbonate butyl ester (15.2 g, 69.64 mmol) and 4-(dimethylamino)pyridine (1.5 g, 12.30 mmol). The reaction mixture was stirred at room temperature overnight. After completion of the reaction, the mixture was partitioned between ethyl acetate and 10% w/v citric acid aqueous solution. The organic layer was separated, washed sequentially with water and brine, and then dried over anhydrous sodium sulfate. The solvent was removed by concentration under reduced pressure and the crude product was purified by silica gel column chromatography to afford methyl 2-(tert-butoxycarbonylamino)thiazole-4-carboxylate as an oil (15.5 g, 95% yield) using 2:3 ethyl acetate/hexane as eluent.