The reaction of 2-amino-N′-arylbenzamidines with tetracyanoethene reinvestigated: routes to imidazoles, quinazolines and quinolino[2′,3′:4,5]imidazo[1,2-c]quinazoline-8-carbonitrile

Styliana I. Mirallai, Maria Manoli, Panayiotis A. Koutentis

Research output: Contribution to journalArticlepeer-review

Abstract

2-Amino-N′-phenylbenzamidine (1a) reacts with tetracyanoethene (TCNE) to give 2-[2-(2-aminophenyl)-5-imino-1-phenyl-1H-imidazol-4(5H)-ylidene]malononitrile (11a), 4-(phenylamino)quinazoline-2-carbonitrile (5a) and 4-imino-3-phenyl-3,4-dihydroquinazoline-2-carbonitrile (9a). By optimizing the reaction conditions each of the compounds can be isolated as the main product and seven examples of these reactions are described. The [1H-imidazol-4(5H)-ylidene]malononitrile 11a was also independently synthesized in three steps from 2-amino-N′-(2-nitrophenyl)benzamidine (25) and TCNE in an overall yield of 56%. Dimroth rearrangement of either 2-aminophenyl- or 2-nitrophenyl-substituted [1H-imidazol-4(5H)-ylidene]malononitriles 11a or 27 with DBU in hot DCM gave the 2-[2-(2-aminophenyl)- and 2-[2-(2-nitrophenyl)-5-(phenylimino)-3H-imidazol-4(5H)-ylidene]malononitriles 28 (71%) and 34 (59%), respectively. Treatment of the [3H-imidazol-4(5H)-ylidene]malononitrile 28 with ethyl orthoformate in DMA at 165°C gave (Z)-2-[3-(phenylimino)imidazo[1,2-c]quinazolin-2(3H)-ylidene]malononitrile (36) (70%), thermolysis of which gave quinolino[3′,2′:4,5]imidazo[1,2-c]quinazoline-13-carbonitrile (30) (97%).

Original languageEnglish
Article number27146
Pages (from-to)8766-8780
Number of pages15
JournalTetrahedron
Volume71
Issue number46
DOIs
Publication statusPublished - 18 Nov 2015

Keywords

  • Amidines
  • Cyclization reactions
  • Heterocycles
  • Imidazoles
  • Quinazolines
  • Tetracyanoethylene

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