- Efficient preparation of 2-azulenylboronate and Miyaura-Suzuki cross-coupling reaction with aryl bromides for easy access to poly(2-azulenyl)benzenes
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This paper describes an efficient preparation of 2-azulenylboronate (6) starting from 2-iodoazulene by halogen-metal exchange reaction using n-BuLi and subsequent quenching with 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane. The boronate 6 has been found to undergo Pd-catalyzed Miyaura-Suzuki cross-coupling reaction with a range of aryl bromides including aromatic poly bromides utilizing Pd2(dba)3-P(t-Bu)3 as a catalyst and establishes a strategy to produce novel poly(2-azulenyl)benzenes, some of which are found to be insoluble in common organic solvents, however. The redox behavior of 2-arylazulenes and poly(2-azulenyl)benzenes was examined by cyclic voltammetry (CV) and compared with those of 6-azulenylbenzene derivatives reported previously.
- Ito, Shunji,Terazono, Tomomi,Kubo, Takahiro,Okujima, Tetsuo,Morita, Noboru,Murafuji, Toshihiro,Sugihara, Yoshikazu,Fujimori, Kunihide,Kawakami, Jun,Tajiri, Akio
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p. 5357 - 5366
(2007/10/03)
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- Coupling reaction of azulenyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolanes with haloazulenes
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In order to study the physicochemical properties of azulene oligomers, the synthesis and a coupling reaction of 2-(2-amino-1,3-bisethoxycarbonyl-6-azulenyl)-4,4,5,5-tetramethyl-1,3,2- dioxaborolane (1) and 2-(2-azulenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (2) were examined.
- Kurotobi, Kei,Tabata, Hiroshi,Miyauchi, Masato,Murafuji, Toshihiro,Sugihara, Yoshikazu
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p. 1013 - 1016
(2007/10/03)
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- Synthesis of 1,1'-, 2,2'-, 1,2'-, and 2,6'-Biazulenes and Their Derivatives by Ullmann Reaction
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Four kinds of biazulenes, 1,1'- (1a), 2,2'- (2a), 1,2'- (3a), and 2,6'-biazulenes (4a), and their derivatives were synthesized by utilizing Ullmann-type coupling of haloazulene derivatives.Ullmann reaction of ethyl 3-iodo- (5a) and 2-iodoazulene-1-carboxylates (6b) gave diethyl 1,1'-biazulene-3,3-dicarboxylate (1b) and diethyl 2,2'-biazulene-1,1'-dicarboxylate (2b), respectively, in excellent yields.The reaction of 2-iodoazulene gave 2a directly.Diethyl 2-chloroazulene-1,3-dicarboxylate (7a) and 5-alkyl derivatives also reacted to give tetraethyl 2,2'-biazulene-1,1',3,3'- tetracarboxylate (2d) and its 5,5'-dialkyl derivatives, respectively.A mixed Ullmann reaction of 5a and 6b afforded a mixture of 1b, 2b, and diethyl 1,2'-biazulene-1',3-dicarboxylate (3b).Similarly, a mixed Ullmann reaction of 7a and diethyl 6-iodoazulene-1,3-dicarboxylate gave a mixture of 2d and tetraethyl 2,6'-biazulene-1,1',3,3'-tetracarboxylate (4b).The parent hydrocarbons of biazulenes, 1a, 2a, 3a, and 4a, could be derived from the corresponding ethoxycarbonyl derivatives, 1b, 2b, 2d, 3b, and 4b, respectively, by decarboxylation.The planarity of biazulenes and their ester derivatives is also discussed on the basis of the spectral data.
- Morita, Tadayoshi,Takase, Kahei
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p. 1144 - 1152
(2007/10/02)
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