Benzimidazole → 1-Benzyl-1H-benzimidazole

HRID 982025Notes

Reaction equation

HRID 982025 reaction equation
[N:1]1[C:5]2[CH:6]=[CH:7][CH:8]=[CH:9][C:4]=2[NH:3][CH:2]=1.[H-].[Na+].[CH2:12](Br)[C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1>O1CCCC1>[CH2:12]([N:1]1[C:5]2[CH:6]=[CH:7][CH:8]=[CH:9][C:4]=2[N:3]=[CH:2]1)[C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1

Participants

5

Reactant 3

HCID 5798BenzimidazoleHCID 7498Benzyl BromideHCID 24758Sodium hydride

Product 1

HCID 5633471-Benzyl-1H-benzimidazoleYield 80%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

A solution of 4.96 g (42 mmol) of benzimidazole in 250 ml of tetrahydrofuran was cooled under N2 atmosphere to 0° C. and treated sequentially with 2.12 g (44 mmol) of sodium hydride (50% dispersion in oil) and 5.0 ml (42 mmol) of benzyl bromide. The resulting suspension was stirred at ambient temperature for 16 h, washed sequentially with water and saturated brine, dried over MgSO4, and concentrated. The resulting oil was taken up in 75 ml of ethyl acetate, triturated with 300 ml of hexane, and filtered. The mother liquor was concentrated and filtered, and the combined solids were dried in vacuo at 50° C. to give 7.00 g (80%) of the desired compound. 1H NMR (CDCl3) δ 5.38 (s,2H), 7.2 (m,2H), 7.3-7.4 (m,6H), 7.83 (br d,1H), 7.96 (br s,1H).

Workup

  1. washwashed sequentially with water and saturated brine
  2. dry with materialdried over MgSO4
  3. concentrationconcentrated
  4. customtriturated with 300 ml of hexane
  5. filtrationfiltered
  6. concentrationThe mother liquor was concentrated
  7. filtrationfiltered
  8. customthe combined solids were dried in vacuo at 50° C.

Sources & evidence

ORD record
ord-e0a4dd0f75e2430b9a45de23611f7082
Source dataset
uspto-grants-1991_02
Patent number
US04994477

Reaction notes

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