4-Chlorobenzaldehyde → ethyl 4-((4-chlorophenyl)(hydroxy)methyl)-1-cyclopropyl-5-(trifluoromethyl)-1H-Pyrazole-3-carboxylate

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Reaction Conditions

Reaction Steps

LDA (3.70 mL, 6.66 mmol) was added dropwise to a stirred solution of ethyl 1-cyclopropyl-5-(trifluoromethyl)-1H-pyrazole-3-carboxylate (Step 40.1) (1.18 g, 4.75 mmol) in THF (30 mL). After 15 minutes at −78° C., a solution of 4-chlorobenzaldehyde (668 mg, 4.75 mmol) in THF (5 mL) was slowly added. The reaction was stirred at −78° C. for 15 min, quenched with 1 mL of saturated NH4Cl solution, partitioned between EtOAc and water and both phases separated. The aq. phase was extracted with EtOAc and the combined organic phases were washed with brine, dried over Na2SO4 and concentrated. The crude was purified by silica gel column chromatography (hexane/20% EtOAc) to afford the title product (1.5 g, 3.40 mmol, 71% yield) as a yellow solid. tR: 1.27 min (LC-MS 2); ESI-MS: 389 [M+H]+ (LC-MS 2); Rf=0.22 (hexane/EtOAc 8:2).

Provenance & Evidence