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92945-28-3

3-(2-METHYLPROPYL)-1H-PYRAZOLE-5-CARBOXYLIC ACID ETHYL ESTER synthesis

2synthesis methods
-

Yield:92945-28-3 68%

Reaction Conditions:

with acetic acid;hydrazine in ethanol at 20; for 12 h;

Steps:

100.a a) Ethyl 5-isobutyl- 1 H-pyrazole-3-carboxylate

To the above solution of ethyl 6-methyl-2,4-dioxo-heptanoate was added acetic acid (9 g, 0.15 mol) and hydrazine monohydrate (8.1 g, 0.15 mol, CAS: 7803-57-8). The reaction mixture was stilTed at room temperature for 12 hours. Volatiles were removed under reduced pressure. The residue was dissolved in ethyl acetate and washed with water and brine. The organic layer was dried over Na2504, filtered, and concentrated under reduced pressure. The crude product waspurified by flash chromatography (silica gel, petroleum ether: ethyl acetate = 20:1 to 2:1 by vol to give ethyl 5-isobutyl-1H-pyrazole-3-carboxylate as a white solid (13 g, 68% yield). MS (ESI): 197.2 ([M+H]j.

References:

WO2016/16292,2016,A1 Location in patent:Page/Page column 86