4-Nitrobenzimidazole → 7-Aminobenzimidazole

HRID 571062Notes

Reaction equation

HRID 571062 reaction equation
[N+:1]([C:4]1[C:12]2[N:11]=[CH:10][NH:9][C:8]=2[CH:7]=[CH:6][CH:5]=1)([O-])=O>CC(O)=O.[Pd]>[NH:9]1[C:8]2[CH:7]=[CH:6][CH:5]=[C:4]([NH2:1])[C:12]=2[N:11]=[CH:10]1

Participants

4

Reactant 1

HCID 1609494-Nitrobenzimidazole

Product 1

HCID 203297-Aminobenzimidazole

Reagents, catalysts & solvents 2

HCID 23938PalladiumCatalystHCID 176Acetic AcidSolvent

Procedure

4-Nitro-1H-benzimidazole was hydrogenated (48 psi) with 1 g 10% Pd/C in HOAc (100 mL) for 3 h. The crude mixture was filtered through a pad of Celite, washing with MeOH, and concentrated. The residue was taken up in 2 M aq HCl and applied to a Phenomenex Strata-X—C ion exchange column (5 g). The column was washed with H2O and MeOH. The washings contained additional material and were applied to another Strata X—C ion exchange column (5 g). The columns were washed with H2O and MeOH. Each of the columns containing product were washed separately with 10% concentrated NH4OH in MeOH and the product collected in fractions. The collected fractions were concentrated to give 1H-Benzimidazol-4-amine as a deep red solid. 1H NMR (500 MHz, d6-DMSO) δ 12.10 (bs, 1 H), 7.98 (s, 1 H), 6.87 (t, J=7.81 Hz, 1 H), 6.72 (d, J=7.82 Hz, 1 H), 6.34 (d, J=7.57 Hz, 1 H), 5.16 (bs, 2 H).

Workup

  1. customfor 3 h
  2. filtrationThe crude mixture was filtered through a pad of Celite
  3. washwashing with MeOH
  4. concentrationconcentrated
  5. washThe column was washed with H2O and MeOH
  6. washThe columns were washed with H2O and MeOH
  7. additionEach of the columns containing product
  8. washwere washed separately with 10% concentrated NH4OH in MeOH
  9. customthe product collected in fractions
  10. concentrationThe collected fractions were concentrated

Sources & evidence

ORD record
ord-551cd3c3d05244c39e7e2d209f05d0a8
Source dataset
uspto-grants-2015_05
Patent number
US09024032B2

Reaction notes

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