Cl[CH2:2][C:3]#[C:4][CH2:5][N:6]1[CH:10]=[CH:9][C:8]([N+:11]([O-:13])=[O:12])=[N:7]1.Cl.[O:15]1CCCC1>CN(C)C=O.C(OCC)(=O)C>[N+:11]([C:8]1[CH:9]=[CH:10][N:6]([CH2:5][C:4]#[C:3][CH2:2][OH:15])[N:7]=1)([O-:13])=[O:12]The 1-(4-chloro-but-2-ynyl)-3-nitro-1H-pyrazole (300 mg, 1.50 mmol) was dissolved in tetrahydrofuran (2 mL) and N,N-dimethylformamide (6 mL). 1.0 M aqueous hydrochloric acid solution (8 mL) was added and the solution was heated to 100° C. while stirring for 36 h in a sealed vial. The solution was diluted with ethyl acetate (100 mL), washed with water (2×50 mL), saturated aqueous brine solution (2×25 mL), dried over magnesium sulfate and concentrated in vacuo to give a waxy yellow solid. Purification by ISCO flash column chromatography (Teledyne Isco RediSep Flash Column 40 g; 15% ethyl acetate/hexanes to 100% ethyl acetate/hexanes) afforded 4-(3-nitro-pyrazol-1-yl)-but-2-yn-1-ol (166 mg, 61%) as an off white solid: H1-NMR (400 MHz, DMSO-d6) δ 4.12 (2H, d, J=6.0 Hz), 5.23 (2H, s), 7.06 (1H, d, J=2.8 Hz), 8.08 (2H, d, J=3.6 Hz).
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