A new bicyclic oxazaborines with a bridged nitrogen atom, their thermic rearrangement and fluorescence properties

• Published in: Journal of organometallic chemistry Vol. 699; pp. 75 - 81
• Main Authors: Josefík, František, Svobodová, Markéta, Bertolasi, Valerio, Šimůnek, Petr, Macháček, Vladimír, Almonasy, Numan, Černošková, Eva
• Format: Journal Article
• Language: English
• Published: LAUSANNE Elsevier B.V 15.02.2012; Elsevier
• Subjects: 2H-[1,2,4,3λ4]triazaborines; [1,3,2λ4]Oxazaborines; Chemistry; Chemistry, Inorganic & Nuclear; Chemistry, Organic; Diazonium tetraphenylborates; Fluorescence; Physical Sciences; Science & Technology; β-Enaminones; [1,3,2λ4]Oxazaborines; Fluorescence; 2H-[1,2,4,3λ4]triazaborines; β-Enaminones; Diazonium tetraphenylborates; ORGANOBORON COMPOUNDS; BORON COMPLEXES; [1,3,2 lambda]Oxazaborines; beta-Enaminones; 2H-[1,2,4,3 lambda]triazaborines; ELECTROLUMINESCENCE; DIPHENYLBORON
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/j.jorganchem.2011.11.004

Cyclic β-enaminones bearing secondary amino group react with 4-substituted benzenediazonium tetraphenylborates in dichloromethane to form substituted bicyclic [1,3,2λ4]oxazaborines The oxazaborines rearrange, on heating to 200°C in the absence of solvent or in DMF or DMSO, to isomeric 2H-[1,2,4,3λ4]triazaborines. Previously prepared [1,3,2λ4]oxazaborines derived from acyclic β-enaminones bearing secondary amino group either did not undergo the rearrangement or with a lot of difficulties and with negligible yield. The fluorescence behaviour of the prepared triazaborines was observed. These compounds fluoresce in 2-methyltetrahydrofurane and in solid state under low temperatures. The enaminones bearing cyclic amino group react with 4-substituted benzenediazonium tetraphenylborate to form new condensed heterocycles – oxazaborines. The condensed triazaborines, showing fluorescence both in 2-methyl THF and in solid state at low temperatures, have been prepared from these oxazaborines. [Display omitted] ►A novel bicyclic [1,3,2λ4]oxazaborines were prepared. ►The oxazaborines rearrange to the triazaborines under various conditions. ►All the boron heterocycles were characterized by means of NMR and also by X-ray. ►Fluorescence properties were studied in various solvents and in the solid state.