[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].C[Si]([N-][Si](C)(C)C)(C)C.[Li+].[Cl:25]C(Cl)(Cl)C(Cl)(Cl)Cl>C1COCC1.[Cl-].[Na+].O>[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-(tetrahydro-2H-pyran-4-yl)-1H-pyrazole (1 equiv) in THF (0.5 M) was added dropwise a 1.0M solution of lithium bis(trimethylsilyl)amide (14 equiv) in THF at −78° C. The reaction was stirred at −78° C. for 30 min before hexachloroethane (1.5 equiv) in THF (1.15 M) was added. The reaction was stirred at −78° C. for 2.5 h then warmed to room temperature. The reaction was diluted with brine (0.23 M) and extracted with ethyl acetate. The combined extracts were washed with brine, dried over sodium sulfate, filtered and concentrated. The crude product was purified by silica gel chromatography (10-20% ethyl acetate in petroleum ether) to afford the desired product (81% yield) as a white solid. MS (ESI) m/z 232.1 [M+H]+.
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