[N+:1]([C:4]1[CH:8]=[CH:7][NH:6][N:5]=1)([O-:3])=[O:2].[H-].[Na+].Br[CH2:12][CH2:13][O:14][Si:15]([C:18]([CH3:21])([CH3:20])[CH3:19])([CH3:17])[CH3:16]>CN(C)C=O.C(OCC)(=O)C>[C:18]([Si:15]([CH3:17])([CH3:16])[O:14][CH2:13][CH2:12][N:6]1[CH:7]=[CH:8][C:4]([N+:1]([O-:3])=[O:2])=[N:5]1)([CH3:21])([CH3:20])[CH3:19]
3-Nitro-1H-pyrazole (prepared in example 3, 250 mg, 2.21 mmol) was dissolved in anhydrous N,N-dimethylformamide (5 mL) and a 60% dispersion of sodium hydride in mineral oil (93 mg, 2.32 mmol) was added while stirring under nitrogen. After the effervescence ceased and the reaction stirred for an additional 10 min, (2-bromo-ethoxy)-tert-butyl-dimethyl-silane (598 mg, 2.50 mmol) was added. The reaction continued to stir under nitrogen for 2 h. The solution was diluted with ethyl acetate (200 mL), washed with water (2×75 mL), saturated aqueous brine solution (75 mL), dried over magnesium sulfate, filtered and concentrated in vacuo. Purification by flash column chromatography (Merck silica gel 60, 40-63 μm; 5% ethyl acetate/hexanes to 25% ethyl acetate/hexanes) afforded 1-[2-(tert-butyl-dimethyl-silanyloxy)-ethyl]-3-nitro-1H-pyrazole (508 mg, 84%) as a yellow oil: H1-NMR (400 MHz, DMSO-d6) δ 0.00 (6H, s), 0.86 (9H, s), 4.03 (2H, t, J=5.6 Hz), 4.40 (2H, t, J=5.2 Hz), 7.11 (1H, d, J=2.4 Hz), 8.06 (1H, d, J=2.4 Hz).
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