Oxonium, trimethyl-, tetrafluoroborate(1-) (1:1) → 2,3-Dimethyl-6-nitro-2H-indazole

HRID 1640705Notes

Reaction equation

HRID 1640705 reaction equation
[CH3:1][C:2]1[C:10]2[C:5](=[CH:6][C:7]([N+:11]([O-:13])=[O:12])=[CH:8][CH:9]=2)[NH:4][N:3]=1.F[B-](F)(F)F.[CH3:19][O+](C)C>CC(C)=O>[CH3:19][N:3]1[C:2]([CH3:1])=[C:10]2[C:5]([CH:6]=[C:7]([N+:11]([O-:13])=[O:12])[CH:8]=[CH:9]2)=[N:4]1

Participants

4

Reactant 2

HCID 2735153Oxonium, trimethyl-, tetrafluoroborate(1-) (1:1)HCID 109210543-Methyl-6-nitro-1H-indazole

Product 1

HCID 104651492,3-Dimethyl-6-nitro-2H-indazoleYield 75.4%

Reagents, catalysts & solvents 1

HCID 180AcetoneSolvent

Procedure

To a stirred solution of 18.5 g (0.11 mol) of 3-methyl-6-nitro-1H-indazole in 350 ml acetone, at room temperature, was added 20 g (0.14 mol) of trimethyloxonium tetrafluoroborate. After the solution was allowed to stir under argon for 3 hours, the solvent was removed under reduced pressure. To the resulting solid was added saturated aqueous NaHCO3 (600 ml) and a 4:1 mixture of chloroform-isopropanol (200 ml), and the mixture was agitated and the layers were separated. The aqueous phase was washed with additional chloroform: isopropanol (4×200 ml) and the combined organic phase was dried (Na2SO4). Filtration and removal of solvent gave a tan solid. The solid was washed with ether (200 ml) to afford 2,3-dimethyl-6-nitro-2H-indazole as a yellow solid (15.85 g, 73%). 1H NMR (300 MHz, d6DMSO) δ 8.51 (s, 1H), 7.94 (d, J=9.1 Hz, 1H), 7.73 (d, J=8.9 Hz, 1H), 4.14 (s, 3H), 2.67 (s, 3H). MS (ES+, m/z) 192 (M+H).

Workup

  1. customthe solvent was removed under reduced pressure
  2. additionTo the resulting solid was added saturated aqueous NaHCO3 (600 ml)
  3. additiona 4:1 mixture of chloroform-isopropanol (200 ml)
  4. stirringthe mixture was agitated
  5. customthe layers were separated
  6. washThe aqueous phase was washed with additional chloroform
  7. dry with materialisopropanol (4×200 ml) and the combined organic phase was dried (Na2SO4)
  8. filtrationFiltration and removal of solvent
  9. customgave a tan solid
  10. washThe solid was washed with ether (200 ml)

Sources & evidence

ORD record
ord-4e75cbfc940b4c959fbd5e4015d2bb83
Source dataset
uspto-grants-2012_02
Patent number
US08114885B2

Reaction notes

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