General procedure for the synthesis of ethyl N-methyl-4-nitro-1H-imidazole-2-carboxylate from ethyl 1-methylimidazole-2-carboxylate: ethyl 1-methylimidazole-2-carboxylate (1.8 g) was dissolved in concentrated sulfuric acid (5 mL) and the solution was cooled to 0 °C. 90% nitric acid (5 mL) was added slowly with stirring, followed by gradually warming the reaction mixture to room temperature and refluxing the reaction for 1.5 hours at -20 °C. Upon completion of the reaction, the mixture was poured into ice (50 mL) to quench the reaction. The reaction mixture was extracted with dichloromethane and the organic phase was dried over anhydrous sodium sulfate and subsequently concentrated under reduced pressure to give the crude product. The crude product was recrystallized using a mixture of carbon tetrachloride and ethanol solvents (1:1, 5 mL) to give ethyl N-methyl-4-nitro-1H-imidazole-2-carboxylate in the form of white crystals. The yield was 1.0543 g with 45% yield. The structure of the product was confirmed by 1H NMR (DMSO-d6) and 13C NMR (DMSO-d6): 1H NMR (DMSO-d6): δ 8.61 (s, 1H), 4.33 (q, 2H, J = 6.4 Hz), 3.97 (s, 3H), 1.29 (t, 3H, J = 6.0 Hz); 13C NMR (DMSO- d6): δ 158.2, 145.4, 135.3, 127.4, 62.2, 37.3, 14.5.
