Azulene-1-azo-2′-thiazoles. Synthesis and properties
作者:Alexandru C. Razus、Liviu Birzan、Stefania Nae、Mirela Nina Surugiu、Valentin Cimpeanu
DOI:10.1002/jhet.5570400607
日期:2003.11
presence of HNO3/H3PO4 followed by the coupling of diazoniumsalts with azulenes in buffered medium. The reactions proved to be general for this class, the yields are, however, considerably influenced by the substituents at thiazole moiety. For the first time a N-oxide provided from an amino substituted five-member nitrogenous heterocycle was diazotized and coupled. The structure of the obtained compounds
在HNO 3 / H 3 PO 4存在下,将2-氨基噻唑重氮化,然后将重氮盐与天青烯偶联,制得几种属于新化合物类别的衍生物,即azulene-1-azo-2'-噻唑在缓冲介质中。事实证明,这类反应是通用的,但是产率受到噻唑部分的取代基的很大影响。第一次是N由氨基取代的五元氮杂环提供的氧化氮被重氮化并偶联。指定了所得化合物的结构,并对其理化性质进行了讨论。由于芳族体系的强烈推挽效应和噻唑部分的固有性质,新的a并偶氮衍生物在UV-Vis中表现出很强的红移。
Syntheses of polycyclic compounds by oxidative coupling of azulene-1-azoarenes
作者:Alexandru C. Razus
DOI:10.1039/a907402c
日期:——
The chemical oxidation of azulene-1-azoarenes with FeCl3 in benzene was studied. For unsubstituted azo compounds, a 4′,4′ coupling takes place yielding biarylic derivatives 4 or 6. 4′-Substituted azulene-1-azobenzenes react depending on the nature of the substituent. Electron-withdrawing substituents such as NO2 increase the oxidation potential of the starting azo compounds and, as a consequence, they hinder the oxidative coupling. On the contrary, electron-releasing substituents such as 4′-methoxy (compound 1b) activate the position 3 in the azulene moiety and coupling in this position takes place as the main pathway; products with three and four azulene moieties coupled in the 1 and 3 positions (11 and 12) were also separated and characterized. The coupling product for the oxidation of compound 1c with a 4′-CH3 substituent results in 15% yield only; large amounts of oligomers and polymers with substituted methyl detected in the reaction mixture prove that in 1c the benzylic position is also a reactive one. A mechanism with a radical cation intermediate generated by the single-electron transfer oxidation of the starting azo compounds is proposed.