Formic Acid → 1H-Benzimidazol-6-ol,1-methyl-(9CI)

HRID 1890919Notes

Reaction equation

HRID 1890919 reaction equation
[CH3:1][NH:2][C:3]1[CH:4]=[C:5]([OH:12])[CH:6]=[CH:7][C:8]=1[N+:9]([O-])=O.[CH:13](O)=O>CO.[Fe]>[CH3:1][N:2]1[C:3]2[CH:4]=[C:5]([OH:12])[CH:6]=[CH:7][C:8]=2[N:9]=[CH:13]1

Participants

5

Reactant 2

HCID 284Formic AcidHCID 146175Phenol, 3-(methylamino)-4-nitro-

Product 1

HCID 124702491H-Benzimidazol-6-ol,1-methyl-(9CI)Yield 94%

Reagents, catalysts & solvents 2

HCID 23925IronCatalystHCID 887MethanolSolvent

Conditions

Temperature
100 °C

Procedure

To a suspension of 3-methylamino-4-nitro-phenol (300 mg, 1.786 mmol) in formic acid (4 mL) was added iron powder (1.0 g, 17.86 mmol). The reaction mixture was stirred at 100° C. overnight, then it was cooled to room temperature and diluted with methanol. The insolubles were filtered and washed with methanol. The filtrate was concentrated in vacuo and adsorbed on silica gel. Purification by flash chromatography on silica gel using a gradient of 0-15% methanol/dichloromethane afforded 249 mg of 3-methyl-3H-benzoimidazol-5-ol as a light brown solid (94% yield): 1H NMR (DMSO-d6) δ 3.71 (s, 3H), 6.69 (dd, 1H), 6.81 (d, 1H), 7.40 (d, 1H), 7.94 (s, 1H), 9.3 (broad s, 1H); MS (m/z) 149 [M+H]+.

Workup

  1. temperatureit was cooled to room temperature
  2. filtrationThe insolubles were filtered
  3. washwashed with methanol
  4. concentrationThe filtrate was concentrated in vacuo
  5. customPurification by flash chromatography on silica gel using a gradient of 0-15% methanol/dichloromethane

Sources & evidence

ORD record
ord-2e99d0b2cecd43889cf38908ecc3a98e
Source dataset
uspto-grants-2013_08
Patent number
US08507489B2

Reaction notes

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