Hexane → Ethyl 2-(5-bromo-2-methyl-pyrazol-3-yl)-2-oxo-acetate

HRID 1774587Notes

Reaction equation

C([Li])CCC.CCCCCC.[Br:12][C:13]1[CH:17]=[C:16](Br)[N:15]([CH3:19])[N:14]=1.Cl[C:21](=[O:27])[C:22]([O:24][CH2:25][CH3:26])=[O:23]>O1CCCC1.[Cu](I)I.O>[Br:12][C:13]1[CH:17]=[C:16]([C:21](=[O:27])[C:22]([O:24][CH2:25][CH3:26])=[O:23])[N:15]([CH3:19])[N:14]=1

Participants

Conditions

Temperature: -78 °C

Procedure

Under nitrogen atmosphere, n-butyllithium 1.6M in hexane (6.5 mL, 10.42 mmol) was added dropwise to a solution of 3,5-dibromo-1-methyl-1H-pyrazole (11d) (2.00 g, 8.34 mmol) in anhydrous tetrahydrofuran (40 mL) at −78° C. After 30 minutes stirring at the same temperature, copper iodide (5.56 g, 29.18 mmol) was added. The temperature was allowed to reach 0° C. for 40 minutes, then cooled to −78° C. Ethyl chlorooxoacetate (2.80 mL, 25.01 mmol) was dropwise added. The mixture was stirred at room temperature for 2 hours. Water (20 mL) was added and the mixture was extracted with ethyl acetate (2×30 mL). The organic layer was washed with a saturated solution of sodium hydrogenocarbonate (20 mL), dried over sodium sulfate and concentrated in vacuo. The residue was purified by flash chromatography on silica gel (cyclohexane/ethyl acetate: 100/0 to 80/20) to provide ethyl 2-(3-bromo-1-methyl-1H-pyrazol-5-yl)-2-oxoacetate (11e) (1.36 g, 5.21 mmol, 62%).

Workup

additionwas added
extractionthe mixture was extracted with ethyl acetate (2×30 mL)
washThe organic layer was washed with a saturated solution of sodium hydrogenocarbonate (20 mL)
dry with materialdried over sodium sulfate
concentrationconcentrated in vacuo
customThe residue was purified by flash chromatography on silica gel (cyclohexane/ethyl acetate: 100/0 to 80/20)

Sources & evidence

ORD record: ord-c018920be68140ee9f693b325799a550
Source dataset: uspto-grants-2016_02
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US09260395B2

Reaction notes

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