The general procedure for the synthesis of ethyl 1,3-dimethyl-1hydro-pyrazole-5-carboxylate from ethyl 3-methylpyrazole-5-carboxylate and dimethyl carbonate is as follows: 0.1 mol ethyl 3-methyl-5-pyrazolecarboxylate, 0.055 mol dimethyl carbonate (DMC), 100 mL xylene, and 2.0 g Cs2CO3 were mixed, and the reaction was carried out at 130140°C for 8 hours. Upon completion of the reaction, the mixture was cooled to room temperature and the solvent was removed by rotary evaporation to afford ethyl 1,3-dimethyl-5-pyrazolecarboxylate as an oil. The product was quantitatively analyzed by high performance liquid chromatography (HPLC) with a purity of 97.7% and a yield of 85.8%.
