ChemicalBook CAS DataBase List 4-bromo-1-methylpyrazole-3-carboxy acid

4-bromo-1-methylpyrazole-3-carboxy acid synthesis

6synthesis methods

Product Name:4-bromo-1-methylpyrazole-3-carboxy acid
CAS Number:84547-84-2
Molecular formula:C5H5BrN2O2
Molecular Weight:205.01

15803-02-8

124-38-9

84547-84-2

1. 600 ml of anhydrous THF was added to a 2L reaction flask under argon protection. 2. 65.4 g of diisopropylamine was added and the reaction system was subsequently cooled to -78 °C via a dry ice acetone bath. 3. 258 ml of 2.5 M n-butyllithium solution was slowly added dropwise at 0 °C. After the dropwise addition, the reaction temperature was raised to 0 °C and maintained for 0.5 h. The reaction system was then cooled to -78 °C again. 4. 80.0 g of 1-methyl-4-bromopyrazole was slowly added dropwise at -78 °C, and after the dropwise addition was completed, the reaction temperature was maintained at -78 °C for 1 hour. 5. dry carbon dioxide gas was passed into the reaction system until TLC detection showed that the reaction was complete. 6. The pH of the reaction solution was slowly adjusted to 2-3 with 1N HCl, at which time a large amount of white solid was precipitated. 7. The reaction mixture was cooled at 0 °C for 3 h, followed by filtration to collect the white solid. 8. The resulting solid was dried at 40 °C for 16 h to give 77.3 g of white solid compound 22 (4-bromo-1-methyl-1H-pyrazole-5-carboxylic acid).

15803-02-8
337 suppliers
$5.00/1g

124-38-9
134 suppliers
$214.00/14L

84547-84-2
97 suppliers
$28.60/5MG

Yield:84547-84-2 77.3 g

Reaction Conditions:

with n-butyllithium;diisopropylamine in tetrahydrofuran;acetone at -78 - 0; for 1 h;Inert atmosphere;

Steps:

11.21 Step 21: Synthesis of Compound 22

tHF (anhydrous) 600 ml was added to a 2 L reaction flask.Diisopropylamine 65.4g,Argon replacement protection,Dry ice acetone was cooled to -78 °C. Add 2.5M n-butyl lithium 258ml,The temperature is raised at 0 ° C for 0.5 h, and the temperature is lowered to -78 ° C.80.0 g of 1-methyl-4-bromopyrazole was added dropwise, and the reaction was maintained at -78 ° C for 1 h.Pass dry carbon dioxide gas until the reaction is complete.TLC showed the reaction was complete, and 1N HCl was added dropwise to adjust pH = 2-3.A large amount of white solid precipitated. After cooling at 0 ° C for 3 h, filter.Drying at 40 ° C for 16 h gave a white solid compound 22 (77.3 g).

References:

CN108264520,2018,A Location in patent:Paragraph 0261; 0262; 0263; 0264; 0265

5775-86-0 Synthesis