[N+:1]([C:4]1[CH:5]=[N:6][N:7]([CH:9]2[CH2:14][CH2:13][O:12][CH2:11][CH2:10]2)[CH:8]=1)([O-:3])=[O:2].[Li+].C[Si]([N-][Si](C)(C)C)(C)C.[Cl:25]C(Cl)(Cl)C(Cl)(Cl)Cl>C1COCC1.[Na+].[Cl-]>[Cl:25][C:8]1[N:7]([CH:9]2[CH2:14][CH2:13][O:12][CH2:11][CH2:10]2)[N:6]=[CH:5][C:4]=1[N+:1]([O-:3])=[O:2]To a solution of 4-nitro-1-tetrahydropyran-4-yl-pyrazole (1.32 g; 6.69 mmol) in THF (15 mL) was added dropwise LHMDS (1 mol/L) in THF (2.0 equiv.; 13.4 mmol) at −78° C. The reaction was stirred at −78° C. for 30 minutes before the addition of hexachloroethane (2.4 g, 10 mmol) in THF (5 mL). The reaction was stirred at −78° C. before warming to room temperature. The reaction was diluted with sat. NaCl and extracted with EtOAc (3×). The combined extracts were washed with brine, dried over sodium sulfate, filtered and concentrated. The crude product was purified by flash chromatography to give 5-chloro-4-nitro-1-(tetrahydro-2H-pyran-4-yl)-1H-pyrazole (0.98 g, 63%).
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