- A versatile method for the synthesis of benzimidazoles from o-nitroanilines and aldehydes in one step via a reductive cyclization
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A highly efficient and versatile method for the synthesis of benzimidazoles was achieved in one step via the Na2S2O4 reduction of o-nitroanilines in the presence of aldehydes. Heating a solution of o-nitroaniline (Ic) and an aldehyde in EtOH or another appropriate solvent, in the presence of aqueous or solid Na2S2O4, provided facile access to a series of 2-substituted N-H benzimidazoles 5a-m containing a wide range of functional groups not always compatible with the existing synthetic methods. This methodology has also been applied to the regioselective synthesis of N-alkyl and N-aryl benzimidazoles 6a-f via the cyclization of the corresponding N-substituted nitroanilines 13a-e, respectively. In addition, the method was applied successfully to the synthesis of other imidazole containing heterocyclic ring systems such as 1H-imidazo[4,5-b]pyridines 14a,b and 1H-imidazo[4,5-f]quinoline 15.
- Yang, Donglai,Fokas, Demosthenes,Li, Jingzhou,Yu, Libing,Baldino, Carmen M.
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- Studies on the Formation of Imidazoquinolines from Quinoline-5,6-diamine and Aromatic Aldehydes
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Condensation of quinoline-5,6-diamine (I) with aromatic aldehydes in acetic acid yields 3H-3-arylmethyl-2-imidazoquinolines (II) and 2-aryl-1H-imidazoquinolines (III).The formation of these compounds has been explained through the intermedia
- Reddy, A. Pandu Ranga,Veeranagaiah, V.
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p. 372 - 376
(2007/10/02)
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- A Facile Synthesis of 2-Substituted Imidazoquinolines
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Condensation of quinoline-5,6-diamine (II) with aliphatic and aromatic acids under catalytic and thermal conditions results in the corresponding 2-alkyl/aryl-1H-imidazoquinolines (I).
- Reddy, A. Pandu Ranga,Veeranagaiah, V.
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p. 673 - 674
(2007/10/02)
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