Formation of Azulenequinone Derivatives from Variously Functionalized Azulenes by Bromine-oxidation |
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| Authors: | Paw-Wang Yang Jhy-An Chen Hidetsugu Wakabayashi Kimio Shindo Teruo Kurihara Chi-Phi Wu Masafumi Yasunami |
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| Institution: | 1. Department of Chemistry, National Taiwan University, Taipei, Taiwan, R.O.C.;2. Department of Chemistry, Faculty of Science, Josai University, Sakado, Saitama 350-02, Japan;3. Department of Chemistry, Chung Yuan Christian University, Chung-Li, Taiwan, R.O.C.;4. Department of Industrial Chemistry, Nihon University, Koriyama, Fukushima 9632, Japan;5. Tokyo Research Laboratories, Kao Corporation, 2-1-3 Bunka, Sumida-ku, Tokyo 1312, Japan |
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| Abstract: | Variously functionalized 1,5- and 1,7-azulenequinones were easily derived in one-pot in 30-50% yield from the bromine-oxidation of 2-methoxyazulene and 2-methyl derivatives of 1-cyano-, 1-methoxycarbonyl- and its 7-isopropyl derivatives, while 1-methoxycarbonylazulene afforded several unstable products from which we could not isolate any azulenequinones. 1-Acetylazulene afforded 3-bromo-1,5- and -1,7-azulenequinones via side-chain brominated intermediates in high yield. 1,3-Dichloroazulene afforded a mixture of 3-chloro-1,5- and ?1,7-azulenequinones, while 1-fluoro- and 1,3-diiodoazulene gave a mixture of 3-bromoazulenequinones. Analogous oxidation of 1,3-difluoroazulene produced 3-fluoroazulenequinones, but we could not isolate them due to its instability. Hydroxy group of 2-(3-hydroxypropyl)azulene was intact during this quinone formation reaction. |
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| Keywords: | Variously functionalized azulenequinones Bromine-oxidation Azulenes One-pot synthesis |
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