Trifluoroacetic acid → Benzimidazole, 4-bromo-6-nitro-2-(trifluoromethyl)-

HRID 1622484Notes

Reaction equation

HRID 1622484 reaction equation
[Br:1][C:2]1[CH:7]=[C:6]([N+:8]([O-:10])=[O:9])[CH:5]=[C:4]([NH2:11])[C:3]=1[NH2:12].[C:13](O)([C:15]([F:18])([F:17])[F:16])=O>>[Br:1][C:2]1[C:3]2[N:12]=[C:13]([C:15]([F:18])([F:17])[F:16])[NH:11][C:4]=2[CH:5]=[C:6]([N+:8]([O-:10])=[O:9])[CH:7]=1

Participants

3

Reactant 2

HCID 6422Trifluoroacetic acidHCID 203480123-Bromo-5-nitrobenzene-1,2-diamine

Product 1

HCID 23091Benzimidazole, 4-bromo-6-nitro-2-(trifluoromethyl)-Yield 53.1%

Conditions

Temperature
85 °C

Procedure

In a 250 mL round-bottom flask a mixture of 3-bromo-5-nitrobenzene-1,2-diamine (10 g, 43.1 mmol) and TFA (23.24 mL, 302 mmol) was heated to 85° C. for 17 hours. The mixture was allowed to cool to RT, and then was concentrated in vacuo to remove the excess TFA. The residue was partitioned between water (100 mL) and ether (100 mL; not soluble in dichloromethane). The phases were separated, and the organic layer was dried over Na2SO4, then filtered and concentrated in vacuo to provide 4-bromo-6-nitro-2-(trifluoromethyl)-1H-benzo[d]imidazole (7.1 g, 22.90 mmol, 53.1% yield) as a brown solid. LCMS and NMR are consistent with structure (NMR contains a trace of ether). MS (ES+) m/e: 308.9, 310.1 [M+H]+; 1H NMR (400 MHz, DMSO-d6) δ ppm 15.09 (br. s., 1H) 8.49-8.66 (m, 1H) 8.36-8.48 (m, 1H)

Workup

  1. temperatureto cool to RT
  2. concentrationwas concentrated in vacuo
  3. customto remove the excess TFA
  4. customThe residue was partitioned between water (100 mL) and ether (100 mL
  5. customThe phases were separated
  6. dry with materialthe organic layer was dried over Na2SO4
  7. filtrationfiltered
  8. concentrationconcentrated in vacuo

Sources & evidence

ORD record
ord-734ae1d6b6c34dd4ab7df36b3fd3c1c1
Source dataset
uspto-grants-2014_07
Patent number
US08778937B2

Reaction notes

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