Sodium hydride → 1-(3,7-dimethyl-2,6(E)-octadienyl)-6-methoxy-1H-1,3-benzimidazole

HRID 1030581Notes

Reaction equation

HRID 1030581 reaction equation
[H-].[Na+].[CH3:3][O:4][C:5]1[CH:6]=[CH:7][C:8]2[NH:12][C:11](S)=[N:10][C:9]=2[CH:14]=1.[CH2:15](Cl)/[CH:16]=[C:17](/[CH2:19][CH2:20][CH:21]=[C:22]([CH3:24])[CH3:23])\[CH3:18]>CN(C)C=O.C(Cl)Cl>[CH3:18]/[C:17](/[CH2:19][CH2:20][CH:21]=[C:22]([CH3:24])[CH3:23])=[CH:16]\[CH2:15][N:10]1[C:9]2[CH:14]=[C:5]([O:4][CH3:3])[CH:6]=[CH:7][C:8]=2[N:12]=[CH:11]1

Participants

6

Reactant 3

HCID 24758Sodium hydrideHCID 6372219Geranyl chlorideHCID 178488140HCID 178488140, compound

Product 1

HCID 867457041-(3,7-dimethyl-2,6(E)-octadienyl)-6-methoxy-1H-1,3-benzimidazoleYield 77%

Reagents, catalysts & solvents 2

HCID 6228DimethylformamideSolvent2×HCID 6344DichloromethaneSolvent

Procedure

To a suspension of sodium hydride (0.25 g, 11 mmol) in dimethylformamide (10 mL) at 0° C. under nitrogen was added 6-methoxy-2-mercaptobenzimidazole (1.98 g, 11 mmol) in dimethylformamide (20 mL). The solution was allowed to stir to ambient temperature, then geranyl chloride (1.9 g, 11 mmol) was added and the reaction mixture stirred at 90° C. overnight. Evaporation of the solvent gave a residue which was dissolved in CH2Cl2, washed with H2O and dried over Na2SO4. Evaporation and flash chromatography (Merck Kieselgel, 5% MeOH/CH2Cl2) gave 1-(3,7-dimethyl-2,6(E)-octadienyl)-6-methoxy-1H-1,3-benzimidazole (free base) (2.4 g, 77%) as a 1:1 mixture of 5- and 6-methoxy isomers. Conversion to the oxalate salt in diethyl ether filtration 10 minutes after addition of oxalic acid gave 500 mg of the title compound as a white solid (pure 6-methoxy by 400 MHz NMR with NOE). m.p. 90°-94° C. NMR (DMSO-d6)δ8.3(s,1H), 7.68(d,J=2 Hz,1H), 7.63(d,J=9 Hz,1H), 7.23(m,1H), 5.3 d,J=7 Hz, 1H), 5.0(m,1H), 4.90(d,J=8 Hz,2H), 2.0(m,4H), 1.70(s,3H), 1.58(s,3H), 1.55(s,3H).

Workup

  1. stirringthe reaction mixture stirred at 90° C. overnight
  2. customEvaporation of the solvent
  3. customgave a residue which
  4. washwashed with H2O
  5. dry with materialdried over Na2SO4
  6. customEvaporation and flash chromatography (Merck Kieselgel, 5% MeOH/CH2Cl2)

Sources & evidence

ORD record
ord-d688696dbefe43d2881f47497b3f4259
Source dataset
uspto-grants-1992_04
Patent number
US05106863

Reaction notes

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