Synthesis
A mixture of 2.11 g of pyrazole-3-carboxylic acid (V), 50 ml of methanol, and 0.5 ml of POCl3 was refluxed for 12 h. After cooling the reaction mixture was concentrated. The resulting crystals were washed with 20% sodium carbonate solution, dried at 55°C (1 mm Hg), and recrystallized from benzene. Methyl 1-methylpyrazole-3-carboxylate (VIII) was obtained similarly from 6.12 g of 1-methyl-3-pyrazole carboxylic acid VI, 50 ml of methanol and 0.5 ml of POCl3 . Yield 10.2 g (72.8%). bp 125°C (1 mm Hg). IR spectrum, ν, cm -1: 1520 (ring), 1730 (C═O). 1H NMR spectrum, δ, ppm (J, Hz): 3.77 s (3H, NCH3), 3.85 s (3H, OCH3), 6.68 d (1H, 4-H, J2.2), 7.1 br. s (1H, 5H). Found, %: C 51.63; H 5.85; N 20.28. C6H8N2O2. Calculated, %: C 51.42; H 5.71; N 20.00.
