Ethoxalyl chloride → ethyl 2-[1-benzyl-5-(3,4-dihydro-2H-1-benzopyran-6-yl)-3-(trifluoromethyl)-1H-pyrazol-4-yl]-2-oxoacetate

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Reaction Conditions

Reaction Steps

Under nitrogen, isopropyl magnesium chloride 2M in tetrahydrofuran (0.30 mL, 0.59 mmol) was added dropwise to a solution of 1-benzyl-4-bromo-5-(3,4-dihydro-2H-1-benzopyran-6-yl)-3-(trifluoromethyl)-1H-pyrazole (49d) (200 mg, 0.46 mmol) in anhydrous tetrahydrofuran (1.0 mL), previously cooled to −20° C. After 2 hour stirring at the same temperature, ethyl chlorooxoacetate (87 μL, 0.78 mmol) was dropwise added. The mixture was stirred at −20° C. for 60 minutes before being poured in water (2 mL). The mixture was extracted with ethyl acetate (2×3 mL) and the organic layer was dried over sodium sulfate and concentrated in vacuo. The residue was purified by preparative TLC (cyclohexane/ethyl acetate 75/25) to provide the desired keto-ester (49e) (80 mg, 0.17 mmol, 38%)

Provenance & Evidence