These common heterocyclic compound, 52867-42-2, name is Methyl 2-methyl-5-oxo-2,5-dihydro-1H-pyrazole-3-carboxylate, its traditional synthetic route has been very mature, but the traditional synthetic route has various shortcomings, such as complicated route, low yield, poor purity, etc, below Introduce a new synthetic route. name: Methyl 2-methyl-5-oxo-2,5-dihydro-1H-pyrazole-3-carboxylate
Step 2: 2-Methyl-5-[2-(tetrahydro-pyran-2-yloxy)-ethoxy]-2H-pyrazole-3-carboxylic acid ethyl ester (3_ 1_3) [00353] Diisopropyl azodicarboxylate (DIAD, 41.6 mL, 205.8 mmol) was added to a solution of 3_41_2 (10.7 g, 68.6 mmol), 2-(tetrahydro-pyran-2-yloxy)- ethanol (17 mL, 102.9 mmol) and triphenylphosphine (53.9 g, 205.8 mmol) at 0C, and the mixture was stirred at room temperature for 16 hours. The reaction mixture was heated at 80C for 16 hours, more 2-(tetrahydro-pyran-2-yloxy)-ethanol (3.75 mL), triphenylphosphine (5.3 g) and diisopropyl azodicarboxylate (3 mL) were added, and the reaction mixture was refluxed for 16 hours, concentrated and treated with diethyl ether and hexanes (2:3, 500 mL) to give a precipitate, which was removed by filtration. The filtrate was concentrated and the residue obtained was purified by column chromatography to give compound 3_41_3 (26.6 g, >100 % yield, contaminated with diisopropyl azodicarboxylate) as a yellow oil. [00354] NMR (400 MHz, CDC13): delta = 1.45-1.90 (m, 6H), 3.52 (d, ]=UA Hz, 1H), 3.79-3.92 (m, 5H), 3.95-4.10 (m, 5H), 4.31 (t, J=4.9 Hz, 2H), 4.69 (t, J=3.5 Hz, 1H), 6.21 (s, 1H).
The synthetic route of Methyl 2-methyl-5-oxo-2,5-dihydro-1H-pyrazole-3-carboxylate has been constantly updated, and we look forward to future research findings.