C([Si](C)(C)[O:6][CH2:7][CH2:8][N:9]1[CH:13]=[CH:12][C:11]([N+:14]([O-:16])=[O:15])=[N:10]1)(C)(C)C.Cl>C(O)C.Cl>[N+:14]([C:11]1[CH:12]=[CH:13][N:9]([CH2:8][CH2:7][OH:6])[N:10]=1)([O-:16])=[O:15]A solution of 1-[2-(tert-butyl-dimethyl-silanyloxy)-ethyl]-3-nitro-1H-pyrazole (prepared as in US 20080021032 Example 67, 6.34 g, 23.36 mmol) in ethanol (100 mL) was treated with concentrated hydrochloric acid (12 drops) and stirred for 1 h at room temperature. After this time, another portion of concentrated hydrochloric acid was added (12 drops) and it was stirred overnight at room temperature. After this time, the reaction mixture was concentrated in vacuo and then azeotroped with acetonitrile. The crude material was then purified by flash column chromatography (silica gel 60, 230-400 mesh, 80% ethyl acetate/hexanes) to afford 2-(3-nitro-pyrazol-1-yl)-ethanol (2.36 g, 94%) as a white solid: 1H NMR (300 MHz, DMSO-d6) δ ppm 8.00 (d, J=2.56 Hz, 1H), 7.03 (d, J=2.56 Hz, 1H), 5.00 (t, J=5.31 Hz, 1H), 4.26 (t, J=5.31 Hz, 2H), 3.77 (q, J=5.49 Hz, 2H).
Loading…
