Potassium Iodide → ethyl 1-benzyl-3-nitro-1H-pyrazole-4-carboxylate

HRID 1426269Notes

Reaction equation

[N+:1]([C:4]1[NH:8][N:7]=[CH:6][C:5]=1[C:9]([O:11][CH2:12][CH3:13])=[O:10])([O-:3])=[O:2].C(=O)([O-])[O-].[K+].[K+].[CH2:20](Br)[C:21]1[CH:26]=[CH:25][CH:24]=[CH:23][CH:22]=1.[I-].[K+]>CN(C)C=O.CCOC(C)=O>[CH2:20]([N:7]1[CH:6]=[C:5]([C:9]([O:11][CH2:12][CH3:13])=[O:10])[C:4]([N+:1]([O-:3])=[O:2])=[N:8]1)[C:21]1[CH:26]=[CH:25][CH:24]=[CH:23][CH:22]=1

Participants

Conditions

Temperature: 60 °C

Procedure

To a solution of C1 (2.86 g, 15.4 mmol) in N,N-dimethylformamide (60 mL) was added anhydrous potassium carbonate (12.8 g, 92.6 mmol), benzyl bromide (2.20 mL, 18.5 mmol) and a catalytic amount of potassium iodide. The reaction was heated at 60° C. for 18 hours, then diluted with EtOAc and washed with water. The organic layer was dried over magnesium sulfate, filtered and concentrated under reduced pressure. Purification using silica gel chromatography (Gradient: 0% to 100% EtOAc in heptane) provided C2 as an oil. Yield: 1.35 g, 4.90 mmol, 32%. An NOE experiment revealed a strong interaction between the pyrazole CH and aromatic protons on the phenyl group, supporting the indicated regiochemistry for C2. LCMS m/z 276.0 (M+1). 1H NMR (400 MHz, CDCl3) δ 1.32 (t, J=7.1 Hz, 3H), 4.31 (q, J=7.1 Hz, 2H), 5.33 (s, 2H), 7.30-7.35 (m, 2H), 7.40-7.45 (m, 3H), 7.78 (s, 1H).

Workup

washwashed with water
dry with materialThe organic layer was dried over magnesium sulfate
filtrationfiltered
concentrationconcentrated under reduced pressure
customPurification

Sources & evidence

ORD record: ord-55db64da5ff64c3395b44048a4907af9
Source dataset: uspto-grants-2015_01
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08933095B2

Reaction notes

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