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Zaki ME, Proença MF, Booth BL. Efficient synthesis of 3H-imidazo[4,5-b]pyridines from malononitrile and 5-amino-4-(cyanoformimidoyl)imidazoles. J Org Chem. 2003;68(2):276-82doi: 10.1021/jo020347f.
Zaki, M. E., Proença, M. F., & Booth, B. L. (2003). Efficient synthesis of 3H-imidazo[4,5-b]pyridines from malononitrile and 5-amino-4-(cyanoformimidoyl)imidazoles. The Journal of organic chemistry, 68(2), 276-82. https://doi.org/10.1021/jo020347f
Zaki, Magdi E A, et al. "Efficient synthesis of 3H-imidazo[4,5-b]pyridines from malononitrile and 5-amino-4-(cyanoformimidoyl)imidazoles." The Journal of organic chemistry vol. 68,2 (2003): 276-82. doi: https://doi.org/10.1021/jo020347f
Zaki ME, Proença MF, Booth BL. Efficient synthesis of 3H-imidazo[4,5-b]pyridines from malononitrile and 5-amino-4-(cyanoformimidoyl)imidazoles. J Org Chem. 2003 Jan 24;68(2):276-82. doi: 10.1021/jo020347f. PMID: 12530849.
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J Org Chem. 2003 Jan 24;68(2):276-82. doi: 10.1021/jo020347f.

Efficient synthesis of 3H-imidazo[4,5-b]pyridines from malononitrile and 5-amino-4-(cyanoformimidoyl)imidazoles.

The Journal of organic chemistry

Magdi E A Zaki, M Fernanda Proença, Brian L Booth

Affiliations

  1. Departamento de Química, Universidade do Minho, Campus de Gualtar, 4710 Braga, Portugal.

PMID: 12530849 DOI: 10.1021/jo020347f

Abstract

1-Aryl-5-amino-4-(cyanoformimidoyl)imidazoles 2 were reacted with malononitrile under mild experimental conditions and led to 3-aryl-5,7-diamino-6-cyano-3H-imidazo[4,5-b]pyridines 5, when the reaction was carried out in the presence of DBU, or to 3-aryl-5-amino-6,7-dicyano-3H-imidazo[4,5-b]pyridines 3, in its absence. Both reactions evolved from the adduct formed by nucleophilic attack of the malononitrile anion to the carbon of the cyanoformimidoyl substituent. A 5-amino-1-aryl-4-(1-amino-2,2-dicyanovinyl)imidazole 4 was isolated when this reaction was carried out in the presence of DBU. The structure of compound 4 was confirmed by spectroscopic methods and by reaction with triethyl orthoformate and with acetic anhydride, leading respectively to 9-aryl-6-(cyanomethylidene)purines 11 and 12. Imidazole 2b was also reacted with ethyl acetoacetate, a carbon acid with a pK(a) comparable to that of malononitrile. Similar reaction conditions were used and the product isolated was a 6-carbamoyl-1,2-dihydropurine 10, showing that a different mechanism was operating in this case.

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