p-Toluenesulfonic acid → Methyl 1H-benzimidazole-4-carboxylate

HRID 1767680Notes

Reaction equation

HRID 1767680 reaction equation
[CH3:1][O:2][C:3](=[O:12])[C:4]1[CH:9]=[CH:8][CH:7]=[C:6]([NH2:10])[C:5]=1[NH2:11].[CH:13](OCC)(OCC)OCC.C1(C)C=CC(S(O)(=O)=O)=CC=1>>[CH3:1][O:2][C:3]([C:4]1[C:5]2[N:11]=[CH:13][NH:10][C:6]=2[CH:7]=[CH:8][CH:9]=1)=[O:12]

Participants

4

Reactant 3

HCID 6101p-Toluenesulfonic acidHCID 31214Ethyl orthoformateHCID 5718252,3-Diaminobenzoic acid methyl ester

Product 1

HCID 14970852Methyl 1H-benzimidazole-4-carboxylate

Conditions

Temperature
90 °C

Procedure

Ester 2 (1.7 g, 10.2 mmol), triethyl orthoformate (2.5 mL) and p-toluenesulfonic acid (10 mg) were mixed in “Performance Fluid” (3M Co., 40 mL) and refluxed with reversed Dean-Stark trap at 90° C. for 3 h. The reaction mixture was cooled to room temperature and the solid formed was filtered, washed with hexanes and dried to give 1.65 g (92%) of pure 3: 1H NMR (DMSO-d6) δ 12.59 (br.s, 1H), 8.32 (s, 1H), 7.97 (d, 1H, J=8.0 Hz), 7.86 (d, 1H, J=6.5 Hz), 7.32 (t1, 1H, J=8.0 Hz), 3.95 (s, 3H).

Workup

  1. temperatureThe reaction mixture was cooled to room temperature
  2. customthe solid formed
  3. filtrationwas filtered
  4. washwashed with hexanes
  5. customdried
  6. customto give 1.65 g (92%) of pure 3

Sources & evidence

ORD record
ord-c0d08671b43b4fb786ad091167c6199b
Source dataset
uspto-grants-2007_06
Patent number
US07235557B2

Reaction notes

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