Acetic Anhydride → (E)-1-(2-pyridyl)-2-[2-(2-pyridyl)ethenyl]-1H-benzimidazole

HRID 50905

Reaktionsgleichung

Reaktionsgleichung von HRID 50905
[CH3:1][C:2]1[N:6]([C:7]2[CH:12]=[CH:11][CH:10]=[CH:9][N:8]=2)[C:5]2[CH:13]=[CH:14][CH:15]=[CH:16][C:4]=2[N:3]=1.[N:17]1[CH:22]=[CH:21][CH:20]=[CH:19][C:18]=1[CH:23]=O.C(OC(=O)C)(=O)C.[OH-].[Na+]>O>[N:8]1[CH:9]=[CH:10][CH:11]=[CH:12][C:7]=1[N:6]1[C:5]2[CH:13]=[CH:14][CH:15]=[CH:16][C:4]=2[N:3]=[C:2]1/[CH:1]=[CH:23]/[C:18]1[CH:19]=[CH:20][CH:21]=[CH:22][N:17]=1

Komponenten

6

Edukt 4

HCID 7918Acetic AnhydrideHCID 142732-PyridinecarboxaldehydeHCID 14798Sodium HydroxideHCID 227366432-Methyl-1-(pyridin-2-yl)-1H-benzimidazole

Produkt 1

HCID 22736658(E)-1-(2-pyridyl)-2-[2-(2-pyridyl)ethenyl]-1H-benzimidazoleAusbeute 25,2 %

Reagenzien, Katalysatoren, Lösungsmittel 1

HCID 962WaterLösungsmittel

Reaktionsbedingungen

Temperatur
80 °C

Versuchsvorschrift

A stirred mixture of 2-methyl-1-(2-pyridyl)-1H-benzimidazole (0.50 g, 2.39), pyridine-2-carboxaldehyde (0.50 g, 4.67 mmol) and acetic anhydride (5 ml) was heated to 80° C. for 1.5 h and then to reflux for about 6 h. After cooling, the mixture was diluted with water (15 ml), basified with a 10% aqueous solution of sodium hydroxide (100 ml) and extracted with dichloromethane (2×100 ml). The combined organic layers were washed with water (100 ml) and extracted with 2 N hydrochloric acid (3×50 ml). The combined aqueous extracts were basified with a 50% aqueous solution of sodium hydroxide (3×50 ml) and extracted with dichloromethane (4×50 ml). The combined organic extracts were washed consecutively with water (100 ml) and brine (100 ml), dried (magnesium sulfate) and concentrated to dryness. Column chromatography (silica gel, 125 g; ethyl acetate) gave 0.18 g of free base (E)-1-(2-pyridyl)-2-[2-(2-pyridyl)ethenyl]-1H-benzimidazole as a brown oil. This product was dissolved into methanol (5 ml), treated with a 10% methanol solution of hydrogen chloride (5 ml) and concentrated to dryness. Recrystallization from 2-propanol afforded 0.15 g (21%) of the titled compound. MW: 371.27; mp: 148.0-155.0° C.; 1H-NMR (DMSO-6) δ: 8.84-8.78 (1H, m), 8.74-8.69 (1H, m), 8.30-8.22 (1H, m), 8.19-8.10 (2H, m), 8.02-7.95 (1H, m), 7.91-7.84 (2H, m), 7.79-7.70 (2H, m), 7.65-7.40 (4H, m).

Aufarbeitung

  1. temperatureto reflux for about 6 h
  2. temperatureAfter cooling
  3. extractionextracted with dichloromethane (2×100 ml)
  4. washThe combined organic layers were washed with water (100 ml)
  5. extractionextracted with 2 N hydrochloric acid (3×50 ml)
  6. extractionextracted with dichloromethane (4×50 ml)
  7. washThe combined organic extracts were washed consecutively with water (100 ml) and brine (100 ml)
  8. dry with materialdried (magnesium sulfate)
  9. concentrationconcentrated to dryness

Quellen und Nachweise

ORD-Eintrag
ord-73feb2e68c154dbaaadf1f58d760ae82
Quelldatensatz
uspto-grants-2004_03
Patentnummer
US06713482B2

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