Allyl bromide → 1H-Pyrazole-5-acetic acid, 1-methyl-4-nitro-α-2-propen-1-yl-, methyl ester

HRID 521857Notes

Reaction equation

[CH3:1][N:2]1[C:6]([CH2:7][C:8]([O:10][CH3:11])=[O:9])=[C:5]([N+:12]([O-:14])=[O:13])[CH:4]=[N:3]1.[H-].[Na+].[CH2:17](Br)[CH:18]=[CH2:19]>CN(C=O)C>[CH3:1][N:2]1[C:6]([CH:7]([CH2:19][CH:18]=[CH2:17])[C:8]([O:10][CH3:11])=[O:9])=[C:5]([N+:12]([O-:14])=[O:13])[CH:4]=[N:3]1

Participants

Conditions

Temperature: 0 °C

Procedure

To a solution of methyl 2-(2-methyl-4-nitro-pyrazol-3-yl)acetate (869 mg, 4.36 mmol) in anhydrous DMF (10 mL) was added at 0° C. sodium hydride (218 mg, 5.45 mmol, 60 mass %), the mixture became dark red right away. After stirring at 0° C. for 15 min, allyl bromide (0.57 mL, 6.54 mmol) was added slowly, stirred at 0° C. for 10 min then room temp for 1 h. The reaction was quenched with water (20 mL) and extracted with EA (200 mL, 50 mL). Combined organic layer was washed with water (15×3 mL), brine (10 mL), dried (MgSO4) and the solvent removed under reduced pressure. The residue was purified via silica gel chromatography (0-100% EtOAc/heptane) to afford methyl 2-(2-methyl-4-nitro-pyrazol-3-yl)pent-4-enoate (713 mg, 68%). 1H NMR (400 MHz, CDCl3) δ 8.10 (s, 1H), 5.71-5.54 (m, 1H), 5.01 (d, J=13.1 Hz, 2H), 4.43 (dd, J=9.8, 5.5 Hz, 1H), 3.86 (s, 3H), 3.72 (s, 3H), 3.14-3.02 (m, 1H), 2.79-2.62 (m, 1H).

Workup

stirringstirred at 0° C. for 10 min
waitroom temp for 1 h
customThe reaction was quenched with water (20 mL)
extractionextracted with EA (200 mL, 50 mL)
washCombined organic layer was washed with water (15×3 mL), brine (10 mL)
dry with materialdried (MgSO4)
customthe solvent removed under reduced pressure
customThe residue was purified via silica gel chromatography (0-100% EtOAc/heptane)

Sources & evidence

ORD record: ord-d1f87df649004c039f1ca78410e60cdb
Source dataset: uspto-grants-2016_05
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US09328106B2

Reaction notes

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