Novel aurone-type compounds with an extended π-system: Synthesis and optical properties

In this paper, a novel family of (E,E)-aminoaurone-type compounds with an extended π-system has been developed, prepared via copper catalysed aza-Michael addition, ring opening, and cyclization between (E)-3-bromo-2-styrylchromones and aniline derivatives in the presence of base under mild reaction conditions. All derivatives showed strong solvatochromic absorption and emission properties, which make them potential compounds for sensing applications. The presence of electron-withdrawing substituents in the aromatic ring had a strong influence on the fluorescence behavior of the aurone-type derivatives. In particular, aurone 3h has promising characteristics, not only for the large Stokes observed, but also for the presence of the C-glycosyl moiety. We conclude that appropriately substituted π-extended aminoaurones are potentially useful as biological probes.