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,
摘要:
AbstractA 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.
3-Bromo derivatives of 1,5- and 1,7-azulenequinones easily react with various nucleophiles to give 3-methoxy, phenoxy, p-nitrophenoxy, butylthio, butylamino, p-tolylamino, dimethylamino, 2-hydroxyethylamino, azulenyl, and guaiazulenyl derivatives of the respective azulenequinones almost quantitatively. 3-Bromo-1,5- and -1,7-azulenequinones afford the 2,3-bisbutylthio derivatives under basic conditions
A very convenient, one-potsynthesis (in ca. 80% yield) of 3-Bromo-1,5- and -1,7-azulenequinones which can be used as synthones has been developed by polybromination of azulenes. Zink dust reduction and reductive acetylation of these azulenequinones were studied, and possible pathways for the present synthesis are briefly discussed.
Photodimerizations of 1,5- and 1,7-Azulenequinones: Solvent, Substituent, and Concentration Effects on the Product Distribution
作者:Hiroko Kawakami、Yong Zhe Yan、Nobuo Kato、Akira Mori、Hitoshi Takeshita、the late Tetsuo Nozoe
DOI:10.1246/bcsj.71.711
日期:1998.3
with a high-pressure mercury lamp. In polar solvents, head-to-head dimers were predominant, whereas head-to-tail dimers increased in less polar solvents. From 3-methoxy-1,5-azulenequinone, four products were obtained, while bromoazulenequinones and 1,5-azulenequinone gave a single dimer. The product distribution was dependent on the polarity of solvents, substituents, and concentrations.
Tetracyanoazulenequinodimethanes and dicyanoazulenequinonemethides, a new family of azulene-based electron acceptors have been derived from mono-, di-, and tri-bromo- and -chloro-azulenequinones by reaction with titanium tetrachloride, malononitrile and pyridine. Their unique electron acceptability has been revealed by CV measurement.
The high-pressure Diels–Alder reaction of 3-bromo-1,5-azulenequinone and 3-bromo-1,7-azulenequinone with several dienophiles under 300 MPa pressure gave 1∶1 [4 + 2] cycloadducts in good yields. Bromoazulenequinones reacted with dienophiles on the seven-membered ring in such a way as not to produce a cyclopentadienone moiety.