Acetic Anhydride → (E)-5-Acetylamino-1-(2-pyridyl)-2-styryl-1H-benzimidazole

HRID 50926Notes

Reaction equation

HRID 50926 reaction equation
[NH2:1][C:2]1[CH:24]=[CH:23][C:5]2[N:6]([C:17]3[CH:22]=[CH:21][CH:20]=[CH:19][N:18]=3)[C:7](/[CH:9]=[CH:10]/[C:11]3[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=3)=[N:8][C:4]=2[CH:3]=1.C(=O)(O)[O-].[Na+].[C:30](OC(=O)C)(=[O:32])[CH3:31]>>[C:30]([NH:1][C:2]1[CH:24]=[CH:23][C:5]2[N:6]([C:17]3[CH:22]=[CH:21][CH:20]=[CH:19][N:18]=3)[C:7](/[CH:9]=[CH:10]/[C:11]3[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=3)=[N:8][C:4]=2[CH:3]=1)(=[O:32])[CH3:31]

Participants

4

Reactant 3

HCID 7918Acetic AnhydrideHCID 516892Sodium BicarbonateHCID 22736667(E)-5-Amino-1-(2-pyridyl)-2-styryl-1H-benzimidazole

Product 1

HCID 22736648(E)-5-Acetylamino-1-(2-pyridyl)-2-styryl-1H-benzimidazoleYield 61%

Procedure

(E)-5-Amino-1-(2-pyridyl)-2-styryl-1H-benzimidazole (199 mg, 0.64 mmol) was dissolved in acetic anhydride (2 ml) and the solution was allowed to maintain at room temperature for 30 min. Then the reaction mixture was poured into saturated aqueous sodium bicarbonate solution (50 ml) and the aqueous mixture was extracted with ethyl acetate (100 ml). The organic extract was washed consecutively with water (50 ml) and brine (50 ml), dried (sodium sulfate) and concentrated in vacuo. The residual solids were purified by column chromatography (silica gel, 50 g; n-hexane/ethyl acetate (1/2)) and then recrystallized from ethyl acetate to afford 139 mg (61%) of the titled compound as yellow solids. MW: 354.41; mp: 105.4-106.9° C.; 1H-NMR (CDCl3) δ: 8.81-8.74 (1H, m), 7.99 (1H, ddd, J=7.7, 7.7, 1.8 Hz), 7.97 (1H, d, J=15.8 Hz), 7.84 (1H, d, J=1.5 Hz), 7.63 (1H, br.s), 7.58-7.43 (5H, m), 7.41-7.30 (4H, m), 7.12 (1H, d, J=15.8 Hz), 2.21 (3H, s).

Workup

  1. extractionthe aqueous mixture was extracted with ethyl acetate (100 ml)
  2. extractionThe organic extract
  3. washwas washed consecutively with water (50 ml) and brine (50 ml)
  4. dry with materialdried (sodium sulfate)
  5. concentrationconcentrated in vacuo
  6. customThe residual solids were purified by column chromatography (silica gel, 50 g; n-hexane/ethyl acetate (1/2))
  7. customrecrystallized from ethyl acetate

Sources & evidence

ORD record
ord-76e253657637476094577ac60be953e4
Source dataset
uspto-grants-2004_03
Patent number
US06713482B2

Reaction notes

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