title: Synthesis and structure of some azo coupled cyclic beta-enaminones.
abstract: The reaction of 3-phenylaminocyclopent-2-en-1-one with 4-methyl, 4-methoxy and 4-chlorobenzenediazonium tetrafluoroborates was used to prepare the azo coupling products 3a-c. It was found that these compounds are present in both CDCl(3) solution and solid phase practically exclusively as (E)-3-phenylamino-2-(4-subst.phenyldiazenyl)cyclopent-2-en-1-ones with N--H...N intramolecular hydrogen bond. The substitution of the phenyl residue of the diazonium salt has no effect on the position of the tautomeric equilibrium. On the other hand, the compounds 4a, b formed by the reaction of 3-phenylamino-1H-inden-1-one with 4-methylbenzene- or benzenediazonium tetrafluoroborates exist in CDCl(3) solution and in solid phase as hydrazone compounds. In the solution they occur as a mixture of three forms, out of which two were identified as E/Z isomers with different types of hydrogen bonds. Compound 5 formed by the reaction of 3-amino-5,5-dimethylcyclohex-2-en-1-one with 4-methoxybenzenediazonium tetrafluoroborate is converted into a stable hydrochloride 5.HCl on standing in CHCl(3) solution; this product exhibits a high degree of delocalization of the positive charge. Its structure was studied by means of X-ray.
authors.affiliation: University of Pardubice, Department of Organic Chemistry, Pardubice, Czech Republic. petr.simunek@upce.cz
authors.forename: Petr
authors.initials: P
authors.lastname: Simůnek
authors.forename: Lucie
authors.initials: L
authors.lastname: Lusková
authors.forename: Markéta
authors.initials: M
authors.lastname: Svobodová
authors.forename: Valerio
authors.initials: V
authors.lastname: Bertolasi
authors.forename: Antonín
authors.initials: A
authors.lastname: Lycka
authors.forename: Vladimír
authors.initials: V
authors.lastname: Machácek