Abstract
An efficient synthesis of 5-heteroaryl- and 5,7-bis(heteroaryl)azulene derivatives was established for first time. The reaction proceeded through electrophilic substitution of 1,3di-tert-butylazulene (1) with the triflates of N-containing heterocycles, in the presence of excess heterocycles, in good yields. The presumed intermediates, 5-(dihydroheteroaryl)azulene derivatives were also available by the reaction with several N-containing heterocycles in the presence of Tf2O under milder reaction, conditions. Treatment of the 5-(dihydroheteroaryl)azulene derivatives with KOH readily gave the desired 5-(heteroaryl)azulene derivatives. Unexpectedly, N(5-azulenyl)pyridinium triflate 17 was also obtained by the reaction of 1 with (trifluoromethylsulfonyl)pyridinium trifluoromethanesulfonate (TPT). 5-Heteroaryl- and 5,7-bis(heteroaryl)azulene derivatives exhibited a significant color change in acetic acid compared to those in dichloromethane due to the development of intramolecular charge-transfer (CT) absorption bands. The redox behavior of these new azulene derivatives was examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV)
Original language | English |
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Pages (from-to) | 1059-1069 |
Number of pages | 11 |
Journal | European Journal of Organic Chemistry |
Issue number | 6 |
DOIs | |
Publication status | Published - 2010 Feb 1 |
Externally published | Yes |
Keywords
- Azulene derivatives
- Electrochemistry
- Electrophilic substitution
- Heterocycles
- Solvatochromism
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry