title: The pseudo-Michael reaction of 1-aryl-4,5-dihydro-1H-imidazol-2-amines with ethyl ethoxymethylenecyanoacetate.
abstract: The pseudo-Michael reaction of 1-aryl-4,5-dihydro-1H-imidazol-2-amines with ethyl 2-cyano-3-methoxyprop-2-enoate (ethyl ethoxymethylenecyanoacetate) is investigated. At -10 °C reaction takes place on the exocyclic nitrogen atom, giving exclusively ethyl esters of 2-cyano-3-[(1-phenyl-4,5-dihydro-1H-imidazol-2-yl)amino]prop-2-enoic acid. The formation of isomeric enamines which may be a theoretical product of the reaction on N3 ring nitrogen atom is not observed. The N6 enamines, heated in boiling acetic acid, yield cyclic 1-aryl-5-oxo-2,3-dihydroimidazo[1,2-a]pyrimidine-6-carbonitriles. Heating of the enamines to the temperature of 120-140 °C without a solvent makes it possible to obtain a mixture of 1-aryl-5-oxo-2,3-dihydroimidazo[1,2-a]pyrimidine-6-carbonitriles and ethyl 1-aryl-5-imino-2,3-dihydroimidazo[1,2-a]pyrimidine-6-carboxylates. The reaction of the respective hydrobromides of 1-aryl-4,5-dihydro-1H-imidazol-2-amines with ethyl ethoxymethylenecyanoacetate in the presence of triethylamine gives selectively 1-aryl-5-oxo-1,2,3,5-dihydroimidazo[1,2-a]pyrimidine-6-carbonitriles.
authors.affiliation: Department of Synthesis and Chemical Technology of Pharmaceutical Substances with Computer Modeling Lab, Faculty of Pharmacy with Division of Medical Analytics, Medical University of Lublin, 4A Chodźki St, 20093 Lublin, Poland.
authors.forename: Agnieszka A
authors.initials: AA
authors.lastname: Kaczor
authors.affiliation: Department of Synthesis and Chemical Technology of Pharmaceutical Substances with Computer Modeling Lab, Faculty of Pharmacy with Division of Medical Analytics, Medical University of Lublin, 4A Chodźki St, 20093 Lublin, Poland.
authors.forename: Urszula
authors.initials: U
authors.lastname: Kijkowska-Murak
authors.affiliation: Department of Chemistry, University of Turku, Vatselankatu 2, 20014 Turku, Finland.
authors.forename: Kalevi
authors.initials: K
authors.lastname: Pihlaja
authors.affiliation: Department of Chemistry, University of Turku, Vatselankatu 2, 20014 Turku, Finland.
authors.forename: Jari
authors.initials: J
authors.lastname: Sinkkonen
authors.affiliation: Department of Chemistry, University of Podlasie, 3 Maja 54 St, 08110 Siedlce, Poland.
authors.forename: Waldemar
authors.initials: W
authors.lastname: Wysocki
authors.affiliation: Department of Chemistry, University of Podlasie, 3 Maja 54 St, 08110 Siedlce, Poland.
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Karczmarzyk
authors.affiliation: Department of Synthesis and Chemical Technology of Pharmaceutical Substances with Computer Modeling Lab, Faculty of Pharmacy with Division of Medical Analytics, Medical University of Lublin, 4A Chodźki St, 20093 Lublin, Poland.
authors.forename: Dariusz
authors.initials: D
authors.lastname: Matosiuk
keywords: Annelation; Michael addition; X-ray structure determination