Thionyl Chloride → 4,5,6,7-Tetrahydro-1H-benzimidazole

HRID 2225619Notes

Reaction equation

HRID 2225619 reaction equation
S(O)(O)(=O)=O.[N:6]1[C:10]2[CH2:11][CH2:12][CH:13](C(O)=O)[CH2:14][C:9]=2[NH:8][CH:7]=1.S(Cl)(Cl)=O>ClCCCl>[N:6]1[C:10]2[CH2:11][CH2:12][CH2:13][CH2:14][C:9]=2[NH:8][CH:7]=1

Participants

4

Reactant 2

HCID 24386Thionyl ChlorideHCID 148567954,5,6,7-Tetrahydrobenzimidazole-5-carboxylic acid sulfate

Product 1

HCID 3042634,5,6,7-Tetrahydro-1H-benzimidazole

Reagents, catalysts & solvents 1

HCID 111,2-DichloroethaneSolvent

Conditions

Temperature
30 °C

Procedure

4,5,6,7-Tetrahydrobenzimidazole-5-carboxylic acid sulfate (1.32 g) was refluxed in 10 ml of 1,2-dichloroethane together with 1.78 g of thionyl chloride for 30 minutes, and the excess of thionyl chloride and the solvent were removed by distillation under reduced pressure. To the residue was added 10 ml of 1,2-dichloroethane, and 1.6 ml of indoline was added dropwise thereto at 30° C. or lower while stirring followed by stirring at room temperature for 2 hours. The reaction mixture was successively extracted once with 30 ml of water and twice with 20 ml of water. The combined aqueous layer was adjusted to a pH of 9 to 10 with a 10% sodium hydroxide aqueous solution and then extracted with methylene chloride. The combined methylene chloride layer was washed with water and dried over anhydrous magnesium sulfate. The solvent was removed by distillation under reduced pressure. The residue was recrystallized from ethyl acetate to obtain 1.1 g (82.7%) of 5-(2,3-dihydroindol-1-yl)carbonyl]-4,5,6,7-tetrahydrobenzimidazole.

Workup

  1. customthe excess of thionyl chloride and the solvent were removed by distillation under reduced pressure
  2. additionTo the residue was added 10 ml of 1,2-dichloroethane, and 1.6 ml of indoline
  3. additionwas added dropwise
  4. stirringby stirring at room temperature for 2 hours
  5. extractionThe reaction mixture was successively extracted once with 30 ml of water and twice with 20 ml of water
  6. extractionextracted with methylene chloride
  7. washThe combined methylene chloride layer was washed with water
  8. dry with materialdried over anhydrous magnesium sulfate
  9. customThe solvent was removed by distillation under reduced pressure
  10. customThe residue was recrystallized from ethyl acetate

Sources & evidence

ORD record
ord-32f08c8d4abb456aa9c829f2f3866452
Source dataset
uspto-grants-1994_09
Patent number
US05344927

Reaction notes

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