Synthesis of 2‐Azulenyl‐1,1,4,4‐tetracyano‐3‐ferrocenyl‐1,3‐butadienes by [2+2] Cycloaddition of (Ferrocenylethynyl)azulenes with Tetracyanoethylene |
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| Authors: | Dr Taku Shoji Prof?Dr Shunji Ito Dr Tetsuo Okujima Prof?Dr Noboru Morita |
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| Institution: | 1. Department of Chemistry, Faculty of Science, Shinshu University, Matsumoto 390‐8621 (Japan), Fax: (+81)?263‐37‐2476;2. Graduate School of Science and Technology, Hirosaki University, Hirosaki 036‐8561 (Japan);3. Department of Chemistry and Biology, Graduate School of Science and Engineering, Ehime University, Matsuyama 790‐8577 (Japan);4. Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980‐8578 (Japan) |
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| Abstract: | 1‐, 2‐, and 6‐(Ferrocenylethynyl)azulene derivatives 10 – 16 have been prepared by palladium‐catalyzed alkynylation of ethynylferrocene with the corresponding haloazulenes under Sonogashira–Hagihara conditions. Compounds 10 – 16 reacted with tetracyanoethylene (TCNE) in a 2+2] cycloaddition–cycloreversion reaction to afford the corresponding 2‐azulenyl‐1,1,4,4,‐tetracyano‐3‐ferrocenyl‐1,3‐butadiene chromophores 17 – 23 in excellent yields. The redox behavior of the novel azulene chromophores 17 – 23 was examined by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV), which revealed their multistep electrochemical reduction properties. Moreover, a significant color change was observed by visible spectroscopy under electrochemical reduction conditions. |
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| Keywords: | azulene cycloaddition donor– acceptor systems electrochemistry ferrocene |
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