Sodium Bicarbonate → 4-hydroxy-1,2-dimethyl-1H-benzimidazole

HRID 2287541Notes

Reaction equation

HRID 2287541 reaction equation
[CH3:1][N:2]1[C:6]2[CH:7]=[CH:8][CH:9]=[C:10]([O:11]C)[C:5]=2[N:4]=[C:3]1[CH3:13].B(Br)(Br)Br.ClCCl.C(=O)(O)[O-].[Na+]>ClCCl>[OH:11][C:10]1[C:5]2[N:4]=[C:3]([CH3:13])[N:2]([CH3:1])[C:6]=2[CH:7]=[CH:8][CH:9]=1

Participants

5

Reactant 3

HCID 516892Sodium BicarbonateHCID 107024241,2-dimethyl-4-methoxy-1H-benzimidazoleHCID 22277759Boron tribromide dichloromethane

Product 1

HCID 104871994-hydroxy-1,2-dimethyl-1H-benzimidazoleYield 57.6%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

To a solution of 1,2-dimethyl-4-methoxy-1H-benzimidazole (560 mg) in dichloromethane (2 ml) was added 1M boron tribromide-dichloromethane solution (6.36 ml) under ice-cooling, and the mixture was stirred for 30 minutes at the same temperature and then for 2 hours at ambient temperature, and refluxed for 14 hours. After cooling, the solution was adjusted to pH 7 with saturated sodium bicarbonate solution, and extracted with dichloromethane twice. The organic layers were combined, washed with brine, dried over magnesium sulfate and evaporated in vacuo. The residue was crystallized with ethyl acetate to give 4-hydroxy-1,2-dimethyl-1H-benzimidazole (297 mg).

Workup

  1. temperaturecooling
  2. waitfor 2 hours at ambient temperature
  3. temperaturerefluxed for 14 hours
  4. temperatureAfter cooling
  5. extractionextracted with dichloromethane twice
  6. washwashed with brine
  7. dry with materialdried over magnesium sulfate
  8. customevaporated in vacuo
  9. customThe residue was crystallized with ethyl acetate

Sources & evidence

ORD record
ord-a8cfc694ec934f74be0d962830e76eeb
Source dataset
uspto-grants-2000_07
Patent number
US06083961

Reaction notes

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