- 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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- ARYLATION OF AZULENE
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In the reaction of azulene with phenylhydrazine and an oxidizing agent (Cu(2+)) a mixture of 1-phenylazulene (28percent) with 2-, 4-, and 6-phenylazulenes (27percent in total) is formed; a series of para-substituted phenylazulenes and α-naphthylazulenes were obtained in a similar way.If p-nitrophenylhydrazine is used, selective arylation of azulene (at position 1) and also of dimethylaniline (at the ortho and para positions) occurs.An excess of the oxidizing agent (Cu(2+)) increases and an excess of the reducing agent (arylhydrazine) reduces the selectivity of arylation.Some of the obtained arylazulenes can be used as dichroic coloring additives for liquid crystals.
- Nefedov, V. A.,German, N. A.,Lutsenko, A. I.,Nikishin, G. I.
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p. 154 - 162
(2007/10/02)
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