Dimethylformamide → (E)-5-Isopropoxy-1-(2-pyridyl)-2-styryl-1H-benzimidazole oxalate

HRID 50930Notes

Reaction equation

HRID 50930 reaction equation
[OH: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:25](=[O:28])([O-:27])[O-].[K+].[K+].Br[CH:32]([CH3:34])[CH3:33].CN(C)C=[O:38]>>[C:2]([OH:1])(=[O:38])[C:25]([OH:27])=[O:28].[CH:32]([O: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)([CH3:34])[CH3:33]

Participants

5

Reactant 4

HCID 6228DimethylformamideHCID 63582-BromopropaneHCID 11430Potassium CarbonateHCID 22736741HCID 22736741, compound

Product 1

HCID 22736705(E)-5-Isopropoxy-1-(2-pyridyl)-2-styryl-1H-benzimidazole oxalateYield 13%

Procedure

According to a literature procedure (Sala, T.; Sargent, M. V. J. Chem. Soc. Perkin Trans. I. 1979, 2593.), to a solution of (E)-5-hydroxy-1-(2-pyridyl)-2-styryl-1H-benzimidazole (63.8 mg, 0.2 mmol) in N,N-dimethylformamide (2 ml), potassium carbonate (140 mg, 1.0 mmol) and 2-bromopropane (0.2 ml, 2.0 mmol) was added at room temperature. This resulting mixture was stirred at room temperature for 19 h. To this mixture, ice-cold water (10 ml) was added and the whole was extracted with ethyl acetate and n-hexane (1:1, 2×20 ml). Combined organic layer was washed with water (2×20 ml), brine (20 ml), dried (magnesium sulfate) and filtered. The filtrate was concentrated and the residue was purified by column chromatography (silica gel, 10 g; n-hexane/ethyl acetate (5/1) to afford the desired compound (9.3 mg, 13%); 1H-NMR (CDCl3) δ: 8.78-8.75 (1H, m), 8.01-7.79 (2H, m), 7.54-7.22 (8H, m), 7.14 (1H, d, J=16.11 Hz), 6.99-6.87 (2H, m), 4.65-4.55 (1H, m), 1.39 (6H, d, J=5.9 Hz). The free base and oxalic acid were dissolved into ethyl acetate. Concentration and recrystallization from ethyl acetate/n-hexane yielded the titled compound. MW: 445.48; mp: 165.0-166.0° C.

Workup

  1. additionwas added at room temperature
  2. extractionthe whole was extracted with ethyl acetate and n-hexane (1:1, 2×20 ml)
  3. washCombined organic layer was washed with water (2×20 ml), brine (20 ml)
  4. dry with materialdried (magnesium sulfate)
  5. filtrationfiltered
  6. concentrationThe filtrate was concentrated
  7. customthe residue was purified by column chromatography (silica gel, 10 g

Sources & evidence

ORD record
ord-e978d9373c534006adee85bbdeac1ba6
Source dataset
uspto-grants-2004_03
Patent number
US06713482B2

Reaction notes

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