Researchers who often do experiments know that organic synthesis is a process of preparing more complex target molecules from simple raw materials through one or more chemical reactions. Generally, it requires fewer steps, and cheap raw materials. 35691-93-1, name is Ethyl 3,5-dimethyl-1H-pyrazole-4-carboxylate, A new synthetic method of this compound is introduced below., Quality Control of Ethyl 3,5-dimethyl-1H-pyrazole-4-carboxylate
A mixture of 2-[2-(3-chloro-5-fluorobenzyl)-1-benzothiophen-7-yl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1.50 g, 3.72 mmol), ethyl 3,5-dimethyl-1H-pyrazole-4-carboxylate (0.76 g, 4.5 mmol) and copper(II) acetate monohydrate (0.37 g, 1.9 mmol) in pyridine (8 mL) was reacted for 20 hr at 50C. The reaction solution was concentrated, and the residue was diluted with ethyl acetate. The organic layer was washed with 1N hydrochloric acid, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate-hexane 1:10) to give ethyl 1-[2-(3-chloro-5-fluorobenzyl)-1-benzothiophen-7-yl]-3,5-dimethyl-1H-pyrazole-4-carboxylate (0.88 g). To a solution of the compound in methanol (20 mL) was added 1N aqueous sodium hydroxide solution (12 mL, 12 mmol) at room temperature, and the mixture was stirred for 1 days at 60C. To the reaction mixture were added water and hydrochloric acid, and the aqueous layer was acidified. The mixture was extracted with ethyl acetate. The organic layer was dried over magnesium sulfate, and evaporated under reduced pressure. The obtained residue was crystallized from ether to give the title compound (630 mg, yield 41%). melting point 187 – 188C. 1H-NMR (DMSO-d6)delta: 2.38 (6 H, s), 4.29 (2 H, s), 7.18 – 7.25 (1 H, m), 7.30 (1 H, s), 7.36 – 7.44 (2 H, m), 7.46 – 7.54 (1 H, m), 7.72 – 7.81 (1 H, m), 7.88 – 7.92 (1 H, m), 12.43 (1 H, br s).
The synthetic route of 35691-93-1 has been constantly updated, and we look forward to future research findings.