16034-46-1, Name is 1-Methyl-1H-pyrazole-5-carboxylic acid, 16034-46-1, belongs to pyrazoles-derivatives compound, is considered to be a conventional heterocyclic compound, which is widely used in drug synthesis. The chemical synthesis route is as follows.
To a solution of tert-butyl [4-methyl-2-(3-methylbenzyl)-1,3-thiazol-5-yl]carbamate (300 g, 0.942 mmol) obtained in Example 221-D) in ethanol (2 mL) was added dropwise concentrated hydrochloric acid (0.670 mL) at room temperature, and the mixture was stirred at 50C for 1.5 hr. The reaction mixture was cooled to 0C, neutralized with 8M aqueous sodium hydroxide solution, adjusted to pH 10-11 with saturated aqueous sodium hydrogen carbonate solution, and extracted with ethyl acetate. The organic layer was dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was dissolved in DMA (9 mL), and 1-methyl-1H-pyrazole-5-carboxylic acid (143 mg, 1.13 mmol), HATU (430 mg, 1.13 mmol) and DIEA (0.0778 mL, 0.471 mmol) were added at room temperature. The reaction mixture was stirred at 60C for 5 hr, water and 0.1N hydrochloric acid were added and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated aqueous sodium hydrogen carbonate solution and saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The obtained residue was purified by silica gel column chromatography [eluent: hexane-ethyl acetate (3:2-3:7)] and basic silica gel column chromatography [eluent: hexane-ethyl acetate (3:2-3:7)], and crystallized from ethyl acetate-hexane to give the title compound (116 mg) as colorless crystals (yield 38%). MS (ESI+): [M+H]+ 327. 1H NMR (300 MHz, DMSO-d6) delta 2.29 (6H, s), 4.04 (3H, s), 4.16 (2H, s), 7.03-7.16 (4H, m), 7.18-7.27 (1H, m), 7.53 (1H, d, J = 1.9 Hz), 10.47 (1H, s).
Statistics shows that 1-Methyl-1H-pyrazole-5-carboxylic acid is playing an increasingly important role. we look forward to future research findings about 16034-46-1.