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288251-64-9

1-(4-FLUOROPHENYL)-3-METHYL-1H-PYRAZOLE-5-CARBOXYLIC ACID ETHYL ESTER synthesis

3synthesis methods
-

Yield:-

Reaction Conditions:

with potassium acetate in ethanol;

Steps:

1.A

4-Fluorophenylhydrazine hydrochloride (25.0 g, 0.154 mol) was added in one portion to a solution of potassium acetate (16.6 g, 0.169 mol) and ethyl acetopyruvate (24.3 g, 0.154 mol) in ethanol (0.154 L). After stirring overnight, methyl tert-butyl ether (0.150 L) was added, the resulting solid was removed by filtration, and the filtrate was concentrated to 40 g of dark oil. This was dissolved in chloroform (100 g), divided into two equal portions, and each portion was purified by prep ηPLC (silica cartridge, eluting with 25% to 40% ethyl acetate in hexane) to separate the two pyrazole isomers. The fractions from both purifications that contained the lower running isomer were combined and concentrated to yield 15.81 g of ethyl l-(4-fluorophenyl)-5-methyl-lH-pyrazole-3- carboxylate as an orange oil. The fractions from both purifications that contained the higher running isomer were combined and concentrated to yield 9.58 g of ethyl l-(4- fluoroρhenyl)-3-methyl-lH-pyrazole-5-carboxylate as an orange solid.

References:

WO2007/79086,2007,A1 Location in patent:Page/Page column 83