Reaktion #9062

Reaktionsgleichung

(2-nitrophenyl)-terephthalamic acid methyl ester

acetic acid

→

methyl 4-(benzimidazol-2-yl)-benzoate

Ausbeute 86.0%

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturat reflux for 1 h
2. 2
   TemperaturThe mixture was cooled
3. 3
   workup.STIRRINGstirred at room temperature for 2 h
4. 4
   Einengenconcentrated under reduced pressure
5. 5
   SonstigeThe residue was partitioned between saturated sodium bicarbonate (10 mL) and ethyl acetate (10 mL)
6. 6
   Sonstigethe phases separated
7. 7
   Waschenthe organic layer washed with saturated NaHCO3 (10 mL)
8. 8
   ExtraktionThe organic extract
9. 9
   Trocknenwas dried (MgSO4)
10. 10
    Filtrationfiltered
11. 11
    Einengenconcentrated

Vorschrift

To a solution of (2-nitrophenyl)-terephthalamic acid methyl ester (0.23 g, 0.76 mmol) in glacial acetic acid (2.5 mL) was added iron powder (<5 μm mesh, 0.12 g, 2.1 mmol) and the mixture stirred at reflux for 1 h. The mixture was cooled, stirred at room temperature for 2 h and concentrated under reduced pressure. The residue was partitioned between saturated sodium bicarbonate (10 mL) and ethyl acetate (10 mL), the phases separated and the organic layer washed with saturated NaHCO3 (10 mL). The organic extract was dried (MgSO4), filtered and concentrated to give cyclized methyl 4-(benzimidazol-2-yl)-benzoate (0.163 g, 86%). 1H NMR (CDCl3) δ 3.96 (s, 3H), 7.32 (m, 2H), 7.53 (br, 1H), 7.84 (br, 1H), 8.17 (m, 4H), 9.65 (br, 1H (NH)).

Quelle