140-40-9

121-66-4

108-24-7

140-40-9

General method: 2-amino-5-nitrothiazole (0.3 g, 2.0 mmol) was dissolved in dichloromethane, followed by the addition of 1.2 molar equivalents of triethylamine (TEA). The reaction mixture was stirred at 5 °C for 15 min, then acetic anhydride (10.0 mmol, 5 eq.) or the corresponding chloride (2.2 mmol, 1.1 eq.) was added slowly and dropwise. The reaction mixture was continued to be stirred at room temperature for 4 to 24 hours. Upon completion of the reaction, the solvent was removed by distillation under reduced pressure. The residue is neutralized with saturated sodium bicarbonate (NaHCO3) solution and the resulting solid is purified by recrystallization from the appropriate solvent mixture.