16034-46-1, In the chemical reaction process, reaction time, type of solvent, can easily affect the result of the reaction, thereby determining the yield and properties of the reaction product. An updated downstream synthesis route of 16034-46-1 as follows.
To a solution of tert-butyl [2-(2,4-dichlorobenzyl)-4-methyl-1,3-thiazol-5-yl]carbamate (536 mg, 1.44 mmol) obtained in Example 155-D) in ethanol (0.9 mL) was added dropwise concentrated hydrochloric acid (3 mL) at 0C, and the mixture was stirred at room temperature for 15 min. The reaction mixture was cooled to 0C, neutralized with 8M aqueous sodium hydroxide solution (4.5 mL), adjusted to pH 10-11 with saturated aqueous sodium hydrogen carbonate solution, and extracted twice with ethyl acetate. The organic layer was washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The obtained residue was dissolved in DMA (5 mL), and 1-methyl-1H-pyrazole-5-carboxylic acid (218 mg, 1.73 mmol) obtained in Example 1-A), HATU (658 mg, 1.73 mmol) and DIEA (0.126 mL, 0.72 mmol) were added at 0C. The reaction mixture was stirred at 60C for 3 hr, water was added, and the mixture was extracted twice with ethyl acetate. The organic layer was washed successively with water, saturated aqueous sodium hydrogen carbonate solution and saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The obtained residue was purified by silica gel column chromatography [eluent: hexane-ethyl acetate (9:1-0:1)] and basic silica gel column chromatography [eluent: hexane-ethyl acetate (9:1-0:1)], and crystallized from ethyl acetate-hexane to give the title compound (314 mg) as yellow crystals (yield 57%). MS (ESI+): [M+H]+ 381. 1H NMR (300 MHz, CDCl3) delta 2.39 (3H, s), 4.20 (3H, s), 4.34 (2H, s), 6.67 (1H, d, J = 1.9 Hz), 7.15-7.36 (2H, m), 7.42 (1H, d, J = 2.3 Hz), 7.52 (1H, d, J = 1.9 Hz), 7.70 (1H brs).
According to the analysis of related databases, 1-Methyl-1H-pyrazole-5-carboxylic acid, the application of this compound in the production field has become more and more popular.