Introduction of a new synthetic route about 5-Methyl-1H-pyrazole-3-carboxylic acid

Statistics shows that 5-Methyl-1H-pyrazole-3-carboxylic acid is playing an increasingly important role. we look forward to future research findings about 402-61-9.

Reference of 402-61-9, These common heterocyclic compound, 402-61-9, name is 5-Methyl-1H-pyrazole-3-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.

A solution of 4.30 g (34.1 mmol) of 5-methyl-1H-pyrazole-3-carboxylic acid in 20 ml of anhydrous DMF was added dropwise at RT within approx. 15 min to a suspension of 5.81 g (35.8 mmol) of 1,1′-carbonyldiimidazole (CDI) in 25 ml of anhydrous DMF. After the mixture had been stirred at RT for 105 min, 8.12 g (34.1 mmol) of the compound from Example 5A/Step 3 were added. Subsequently, the reaction mixture was heated to 110 C. for 5 h. After cooling to RT, the mixture was stirred gradually into 800 ml of water. In the course of this, the product precipitated out. It was filtered off with suction and washed with water. Subsequently, the moist crude product was recrystallized from 430 ml of ethanol. After the solid had been filtered and dried, 8.31 g (74% of theory) of the title compound were obtained. A further fraction was obtained by concentrating the mother liquor (1.69 g with 85% purity, 13% of theory).1H NMR (400 MHz, CDCl3, delta/ppm): 10.73 (broad, 1H), 8.20 (d, 2H), 7.52 (d, 2H), 6.81 (s, 1H), 4.00-3.88 (m, 4H), 2.45 (s, 3H), 2.30-2.11 (m, 2H), 1.98-1.91 (m, 2H).LC/MS (method 1, ESIpos): Rt=4.24 min, m/z=329 [M+H]+.

Statistics shows that 5-Methyl-1H-pyrazole-3-carboxylic acid is playing an increasingly important role. we look forward to future research findings about 402-61-9.