ChemicalBook CAS DataBase List 4-BROMO-3-ETHYL-1-METHYL-1H-PYRAZOLE-5-CARBOXYLIC ACID ETHYL ESTER

4-BROMO-3-ETHYL-1-METHYL-1H-PYRAZOLE-5-CARBOXYLIC ACID ETHYL ESTER synthesis

4synthesis methods

Product Name:4-BROMO-3-ETHYL-1-METHYL-1H-PYRAZOLE-5-CARBOXYLIC ACID ETHYL ESTER
CAS Number:128537-28-0
Molecular formula:C9H13BrN2O2
Molecular Weight:261.12

3-ETHYL-1-METHYL-1H-PYRAZOLE-5-CARBOXYLIC ACID ETHYL ESTER

128537-26-8
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4-BROMO-3-ETHYL-1-METHYL-1H-PYRAZOLE-5-CARBOXYLIC ACID ETHYL ESTER

128537-28-0
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Yield:128537-28-0 80%

Reaction Conditions:

with bromine in dichloromethane at 0 - 10; for 3 h;

Steps:

Ethyl 4-bromo-3-ethyl-1 -methyl-1 H-pyrazole-5-carboxylate

To a solution of ethyl 3-ethyl-1 -methyl-1 H-pyrazole-5-carboxylate (see intermediate 17, 250 g, 1 .37 mol, 1 eq) in dichloromethane (3800 mL) was added bromine (658 g, 4.12 mol, 212.18 ml_, 3 eq) dropwise at 0 O. The mixture was stirred at 10 O for 3 hours. The reaction was stopped by the addition of an aqueous sodium hydrosulfite solution (1500 mL), and the mixture was then diluted with water (500 mL), and was extracted with dichloromethane (800 mL) thrice. The combined organic layers were washed with brine (800 mL), dried over sodium sulfate, filtered and concentrated under reduced pressure to give the title compound (300 g, 80% yield, 96% purity) as a yellow solid.¹H NMR (MeOD, 400MHz) d [ppm]: 4.33 - 4.43 (m, 2H), 4.07 (s, 3H), 2.61 (q, J = 7.65 Hz, 2H), 1 .40 (t, J = 7.15 Hz, 3H), 1 .17 - 1.24 (m, 3H)

References:

WO2019/96907,2019,A1 Location in patent:Page/Page column 140