Application
3-Methyl-1H-indazole-5-amine is an important pharmaceutical intermediate used to construct the core of active drug molecules, and it has broad application prospects in the synthesis and screening of small molecule chemical drugs.
Synthesis
55g of
2-amino-5-nitrotoluene was dissolved in 2.5L of glacial acetic acid, cooled, and a solution prepared by adding 25g of sodium nitrite and 60ml of water was added, and the temperature of the reaction was not more than 25. The yellow precipitate produced was filtered off, the reaction solution was left for 3d and then concentrated under reduced pressure, the residue was stirred to a paste with 200 ml of water, filtered, the filter cake was washed with cold water, dried, and recrystallized from methanol to give 42-47 g of .
5-nitroindazole, yield 72%-80%.
In a three-mouth reaction flask add N,N-dimethylformamide solution, 5-nitroindazole, stirring for 30 minutes, 0 slowly drop of iodomethane, drop is completed, warm up to room temperature reaction. Thin layer chromatography to detect the progress of the reaction, the reaction is complete, add ethyl acetate, water wash 3 to 4 times, the organic phase is dried with anhydrous magnesium sulfate, filtration, concentration of the product 5-nitro-3-methyl-1H-indazole.
Add 5-nitro-3-methyl-1H-indazole and methanol in a 2L single-necked flask, stir to dissolve and then add Pd/C (10g, Pd:C=10:1), exclude the air and then pass hydrogen. The reaction was stirred at room temperature for 4 h. The reaction was complete. Filtering to remove Pd/C, the filtrate was evaporated to remove the solvent to obtain a solid crude, dissolved in 500 mL of ethyl acetate, washed with 200 mL of water, the organic phase was dried with anhydrous sodium sulfate, the filtrate was evaporated to remove the solvent, and the residue was slurried with n-hexane and dried to obtain the target compound 3-methyl-1H-indazol-5-amine.
