Ito Shunji, Okujima Tetsuo, Kikuchi Shigeru, Shoji Taku, Morita Noboru, Asao Toyonobu, Ikoma Tadaaki, Tero-Kubota Shozo, Kawakami Jun, Tajiri Akio
Graduate School of Science and Technology, Hirosaki University, Hirosaki 036-8561, Japan.
J Org Chem. 2008 Mar 21;73(6):2256-63. doi: 10.1021/jo702309b. Epub 2008 Feb 16.
Several azulene-substituted thioketones, 1-thiobenzoylazulene (1a) and di(1-azulenyl) thioketone (2a) and their derivatives (1b and 2b-d) with alkyl substituents on each azulene ring, were prepared and their intramolecular pericyclization reaction was examined. The thioketones with a 3-alkyl substituent on each azulene ring exhibited the presumed pericyclization reaction under thermal and acid-catalyzed conditions, although the cases of the 1-azulenyl thioketones without the 3-alkyl substituents afforded a complex mixture under similar conditions. The intramolecular reaction following the intramolecular hydrogen transfer afforded the products 13b, 14b, and 14c. The products 13b and 14b were converted into the corresponding cations 18(+) and 19(+), which have structural similarity with that of the phenalenyl cation. These cations exhibited the expected two-step reduction waves upon CV, although the ESR analysis revealed that the neutral radical state did not have the presumed high stability.
制备了几种薁取代的硫酮、1-硫代苯甲酰薁（1a）和二（1-薁基）硫酮（2a）及其在每个薁环上带有烷基取代基的衍生物（1b和2b - d），并研究了它们的分子内周环化反应。尽管在每个薁环上带有3 - 烷基取代基的硫酮在热和酸催化条件下表现出推测的周环化反应，但在类似条件下，没有3 - 烷基取代基的1 - 薁基硫酮的情况得到的是复杂混合物。分子内氢转移后的分子内反应得到了产物13b、14b和14c。产物13b和14b被转化为相应的阳离子18(+)和19(+)，它们与苊烯基阳离子具有结构相似性。这些阳离子在循环伏安法（CV）中表现出预期的两步还原波，尽管电子自旋共振（ESR）分析表明中性自由基态没有推测的高稳定性。
