Application of 16034-46-1, These common heterocyclic compound, 16034-46-1, name is 1-Methyl-1H-pyrazole-5-carboxylic acid, 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.
To a solution of tert-butyl [2-(3-methoxybenzyl)-4-methyl-1,3-thiazol-5-yl]carbamate (1.0 g, 2.99 mmol) obtained in Example 219-D) in ethanol (9 mL) was added dropwise concentrated hydrochloric acid (2.3 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 (20 mL), and 1-methyl-1H-pyrazole-5-carboxylic acid (453 mg, 3.59 mmol), HATU (1.37 g, 3.59 mmol) and DIEA (0.247 mL, 1.50 mmol) were added at room temperature. The reaction mixture was stirred at 60C for 2 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 (13:7-1:4)] 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 (545 mg) as colorless crystals (yield 53%). MS (ESI+): [M+H]+ 343. 1H NMR (300 MHz, DMSO-d6) delta 2.30 (3H, s), 3.74 (3H, s), 4.04 (3H, s), 4.17 (2H, s), 6.80-6.94 (3H, m), 7.06 (1H, d, J = 2.3 Hz), 7.22-7.30 (1H, m), 7.53 (1H, d, J = 2.3 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.