Methyl 2-methylbenzimidazole-5-carboxylate hydrochloride → Methyl 2-methyl-4,5,6,7-tetrahydro-1H-benzo[d]imidazole-6-carboxylate

HRID 1110810Notes

Reaction equation

HRID 1110810 reaction equation
Cl.[CH3:2][C:3]1[NH:4][C:5]2[CH:11]=[C:10]([C:12]([O:14][CH3:15])=[O:13])[CH:9]=[CH:8][C:6]=2[N:7]=1>S([O-])([O-])(=O)=O.[Ba+2].[Pd+2].S([O-])([O-])(=O)=O.C(O)(=O)C>[CH3:2][C:3]1[NH:4][C:5]2[CH2:11][CH:10]([C:12]([O:14][CH3:15])=[O:13])[CH2:9][CH2:8][C:6]=2[N:7]=1

Participants

4

Reactant 1

HCID 22154382Methyl 2-methylbenzimidazole-5-carboxylate hydrochloride

Product 1

HCID 10797890Methyl 2-methyl-4,5,6,7-tetrahydro-1H-benzo[d]imidazole-6-carboxylateYield 12%

Reagents, catalysts & solvents 2

HCID 17887766Palladium barium sulphateCatalystHCID 176Acetic AcidSolvent

Procedure

In an autoclave 6.8 g (30 mmols) of methyl 2-methylbenzimidazole-5-carboxylate hydrochloride, 6.0 g of 5% palladium-barium sulfate and 140 ml of acetic acid were charged and hydrogenation was carried out at 80° C. for 115 hours under 60 atms with stirring. After cooling, 5% palladium-barium sulfate was filtered off and the filtrate was distilled off under reduced pressure. After 200 ml of water was added to the residue, 1 N sodium hydroxide solution was added to the mixture at 0° to 5° C. to adjust pH to 9 to 10 followed by extraction with ethyl acetate. The ethyl acetate layer was dried over anhydrous magnesium sulfate and the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography and eluted with methylene chloride-methanol (10 : 1) to give 0.70 g (12.0%) of methyl 2-methyl-4,5,6,7-tetrahydrobenzimidazole-5-carboxylate.

Workup

  1. temperatureAfter cooling
  2. filtration5% palladium-barium sulfate was filtered off
  3. distillationthe filtrate was distilled off under reduced pressure
  4. additionAfter 200 ml of water was added to the residue, 1 N sodium hydroxide solution
  5. additionwas added to the mixture at 0° to 5° C.
  6. extractionfollowed by extraction with ethyl acetate
  7. dry with materialThe ethyl acetate layer was dried over anhydrous magnesium sulfate
  8. distillationthe solvent was distilled off under reduced pressure
  9. washeluted with methylene chloride-methanol (10 : 1)

Sources & evidence

ORD record
ord-3b666d317a6945f8b69ffc0b82f44ec5
Source dataset
uspto-grants-1990_12
Patent number
US04977175

Reaction notes

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