In the next few decades, the world population will flourish. As the population grows rapidly and people all over the world use more and more resources, all industries must consider their environmental impact. 63237-88-7, name is Pyrazolo[1,5-a]pyridine-2-carboxylic acid, the common compound, a new synthetic route is introduced below. name: Pyrazolo[1,5-a]pyridine-2-carboxylic acid
Reference Example 43-1 (R)-2-methyl-N-((R)-1-(pyrazolo[1,5-a]pyridin-2-yl)ethyl)propane-2-sulfinamide Pyrazolo[1,5-a]pyridine-2,3-dicarboxylic acid dimethyl ester (3.35 g, 14 mmol) was dissolved in 50% sulfuric acid (110 mL), and the solution was stirred for 2.5 hours at 80C. The reaction liquid was cooled to 0C, and a 8 M aqueous solution of sodium hydroxide was added thereto to adjust the pH to 9. Subsequently, the pH was adjusted to 3 with 6 M hydrochloric acid. A suspension liquid thus produced was separated by filtration, and crystals were washed with water and then dried under reduced pressure. Thus, pyrazolo[1,5-a]pyridine-2-carboxylic acid (pale brown crystals, 1.88 g, 81%) was obtained. In a nitrogen atmosphere, pyrazolo[1,5-a]pyridine-2-carboxylic acid (941 mg, 5.8 mmol) thus obtained was dissolved in THF (30 mL), and the solution was stirred for a while at room temperature. Subsequently, a THF solution of a borane-THF complex (20 mL, 18 mmol, 0.9 M) was added to the solution, and the mixture was stirred for 3.5 hours at 70C. The reaction liquid was cooled to 0C, water was added thereto, and the mixture was stirred for a while. Subsequently, 6 N hydrochloric acid was added thereto, and the mixture was heated to reflux for one hour. The solvent was distilled off under reduced pressure, subsequently methanol was added thereto, and the solvent was distilled off again. A residue thus obtained was diluted with ethyl acetate, and the organic layer was washed with a 1 N aqueous solution of sodium hydroxide, water, and saturated brine. The organic layer was dried over anhydrous sodium sulfate, insoluble matters were filtered, and then the solvent was distilled off under reduced pressure. Thus, pyrazolo[1,5-a]pyridin-2-ylmethanol was obtained. According to a technique similar to that of Reference Example 13-3, pyrazolo[1,5-a]pyridine-2-carboaldehyde was obtained using pyrazolo[1,5-a]pyridin-2-ylmethanol thus obtained. According to a technique similar to that of Reference Example 1-2, (R)-2-methyl-N-(pyrazolo[1,5-a]pyridin-2-ylmethylene)propane-2-sulfinamide was obtained using pyrazolo[1,5-a]pyridine-2-carboaldehyde thus obtained and (R)-2-methylpropane-2-sulfinamide. According to a technique similar to that of Reference Example 1-3, the title compound (pale yellow oily material, 498 mg, 65%) was obtained using (R)-2-methyl-N-(pyrazolo[1,5-a]pyridin-2-ylmethylene)propane-2-sulfinamide thus obtained.
The synthetic route of 63237-88-7 has been constantly updated, and we look forward to future research findings.
Reference:
Patent; Nippon Chemiphar Co., Ltd.; Kinki University; TANAKA Hiroto; OOI Isao; MOGI Yuzo; HIROSE Masaaki; ENDO Tsuyoshi; OGAWA Toru; KAWABATA Atsufumi; (171 pag.)EP3404021; (2018); A1;,
Pyridine – Wikipedia,
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