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0 °C

In a round bottomed flask was placed 2-methyl-1-(3-nitro-pyrazol-1-yl)-propan-2-ol (170 mg, 0.92 mmol) and N,N-dimethylformamide (5 mL) and it was placed in an ice bath and cooled to 0° C. To this stirred solution was added triethylsilyl chloride (169 mL, 1.01 mmol) and imidazole (156 mg, 2.30 mmol) and it was stirred at 0° C. and slowly warmed to 25° C. and stirred for two days. The reaction was then diluted with ethyl acetate (15 mL) and washed with a saturated aqueous brine solution (10 mL). The aqueous layer was then extracted with ethyl acetate (2×15 mL). The organic layers were then combined and dried over sodium sulfate, filtered and concentrated in vacuo. Purification by AnaLogix Intelliflash system (4 g column, 5% ethyl acetate/hexanes to 20% ethyl acetate/hexanes) afforded 1-(2-methyl-2-triethylsilanyloxy-propyl)-3-nitro-1H-pyrazole (197 mg, 72%) as a clear colorless oil: ES-HRMS m/e calcd for C13H25N3O3Si (M+H)+ 300.1738, observed 300.1737; 1H NMR (300 MHz, CDCl3) δ ppm 0.58 (q, J=8.0 Hz, 6H, 3×SiCH2), 0.92 (t, J=8.0 Hz, 9H, 3×CH3), 1.26 (s, 6H, 2×CH3), 4.12 (s, 2H, NCH2), 6.89 (d, J=2.5 Hz, 1H, Ar), 7.56 (d, J=2.5 Hz, 1H, Ar).

1. customIn a round bottomed flask was placed
2. temperatureslowly warmed to 25° C.
3. stirringstirred for two days
4. washwashed with a saturated aqueous brine solution (10 mL)
5. extractionThe aqueous layer was then extracted with ethyl acetate (2×15 mL)
6. dry with materialdried over sodium sulfate
7. filtrationfiltered
8. concentrationconcentrated in vacuo
9. customPurification by AnaLogix Intelliflash system (4 g column, 5% ethyl acetate/hexanes to 20% ethyl acetate/hexanes)