- Synthesis and Reactivities of 1,5- and 1,7-Azulenequinone Derivatives. A Highly Convenient, One-Pot Synthesis of 3-Bromo-1,5- and -1,7-Azulenequinones by Bromination of Azulene 1,2
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A very convenient, one-pot synthesis (over 80% yield) of 3-bromo-1,5- and -1,7-azulenequinones has been developed by bromination of azulene in aqueous tetrahydrofuran. Reduction of 3-bromo-1,5- and -1,7-azulenequinones with tin or zinc powder in acetic acid gave the parent 1,5- and 1,7-azulenequinones, and further reduction products.
- Wakabayashi, Hidetsugu,Kurihara, Teruo,Shindo, Kimio,Tsukada, Masaaki,Yang, Paw-Wang,Yasunami, Masafumi,Nozoe, Tetsuo
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p. 391 - 400
(2007/10/03)
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- Formation of Azulenequinone Derivatives from Variously Functionalized Azulenes by Bromine-oxidation
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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.
- Yang, Paw-Wang,Chen, Jhy-An,Wakabayashi, Hidetsugu,Shindo, Kimio,Kurihara, Teruo,Wu, Chi-Phi,Yasunami, Masafumi,Nozoe, Tetsuo
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