title: Reactions of tetracyanoethylene with N'-arylbenzamidines: a route to 2-phenyl-3H-imidazo[4,5-b]quinoline-9-carbonitriles.
abstract: Eight 2-phenyl-3H-imidazo[4,5-b]quinoline-9-carbonitriles 15 are prepared in four steps from N'-arylbenzamidines 11 and tetracyanoethylene (TCNE) in ~70-90% yields. The transformation involves the initial formation of N-aryl-N'-(1,2,2-tricyanovinyl)benzamidines 12 in 87-99% yields, which in MeCN undergo a 5-exodig cyclization to give the 2-[1-aryl-5-imino-2-phenyl-1H-imidazol-4(5H)-ylidene]malononitriles 13 in 84-92% yields, while in MeOH the (Z)-2-[2-phenyl-4-(arylimino)-1H-imidazol-5(4H)-ylidene]malononitriles 14 are formed in 85-94% yields. The imidazoles 14 can also be prepared directly from imidazoles 13 via a Dimroth rearrangement in either neat MeOH or in DCM with DBU. Subsequent thermolysis of imidazoles 14 in diphenyl ether affords 2-phenyl-3H-imidazo[4,5-b]quinoline-9-carbonitriles 15 in near quantitative yields. Mechanistic rationale is provided for all transformations.
authors.affiliation: Department of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus.
authors.forename: Styliana I
authors.initials: SI
authors.lastname: Mirallai
authors.forename: Maria
authors.initials: M
authors.lastname: Manoli
authors.forename: Panayiotis A
authors.initials: PA
authors.lastname: Koutentis
mesh_terms: D001550:Benzamidines / Q000737:chemistry*; D005030:Ethylenes / Q000737:chemistry*; D007093:Imidazoles / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D009570:Nitriles / Q000737:chemistry*; D011804:Quinolines / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D001550:Benzamidines; D005030:Ethylenes; D007093:Imidazoles; D009570:Nitriles; D011804:Quinolines; C003393:tetracyanoethylene