Protonation-Induced Cyclocondensation of 1-Aryl Ethynylanthraquinones: Expanding the π Conjugation

Protonation-Induced Cyclocondensation of 1-Aryl Ethynylanthraquinones: Expanding the π Conjugation

Just add a proton: The cyclocondensation of 1‐aryl ethynylanthraquinones in the presence of a strong organic acid proceeds almost quantitatively to give oxodihydrodibenzochromenylium compounds (see scheme for a 1‐ferrocenyl derivative; blue C, red O, purple Fe). Expansion of the π‐conjugated system...

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Veröffentlicht in:Angewandte Chemie (International ed.) 2007-01, Vol.46 (33), p.6271-6274
Hauptverfasser: Kondo, Mio, Uchikawa, Maai, Zhang, Wen-Wei, Namiki, Kosuke, Kume, Shoko, Murata, Masaki, Kobayashi, Yoshio, Nishihara, Hiroshi
Format: Artikel
Sprache:eng
Schlagworte:
anthraquinone
cyclocondensation
fused-ring systems
protonation
tautomerism
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Zusammenfassung:Just add a proton: The cyclocondensation of 1‐aryl ethynylanthraquinones in the presence of a strong organic acid proceeds almost quantitatively to give oxodihydrodibenzochromenylium compounds (see scheme for a 1‐ferrocenyl derivative; blue C, red O, purple Fe). Expansion of the π‐conjugated system of the starting anthraquinones causes a lowering of the π* orbital and promotes intramolecular electron transfer.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.200701766