Development of novel functional compounds with pyridoimidazopyrazine and its analogous skeleton

以前我们报道了以二氨基马来腈为起始原料合成吡啶并[1 '，2'：1，2]咪唑并[4，5-B]吡嗪的新方法。这些产物具有很强的荧光，根据进一步的研究，其中一些，如7-甲基或7-苯基衍生物，显示出0.6 - 0.8的优异荧光量子产率。为了进一步开展这类功能的研究，我们合成了具有类似骨架的化合物，并对其进行了光化学研究。几种取代的邻苯二胺与草酸反应，再经氯化得到相应的6-取代-2，3-二氯喹啉。然后将这些中间体与几种2-氨基吡啶缩合，形成最终产物，新的吡啶并[1 '，2'：1，2]咪唑并[4，5-B]喹喔啉。一种替代的合成路线也被应用到制备各种各样的衍生物。即用2，3-二氯喹啉进行部分胺化反应得到6-取代-2-氨基-3-氯喹啉类化合物，再用4-苯基吡啶、4，4 ′-联吡啶等取代吡啶类化合物进行处理，得到一系列吡啶并咪唑并喹啉类化合物，并对其进行紫外光谱和荧光光谱的研究，发现它们具有很好的荧光活性，其中一些指示0.6 - 0.7的荧光量子产率。取代基的影响也被澄清。

Previously we reported the novel syntheses of pyrido [1',2':1,2] imidazo [4, 5-b] pyrazines, starting from diaminomaleonitrile. These products are highly fluorescent and, according to the further investigation, some of them, such as 7-methyl or 7-phenyl derivative, showed an excellent fluorescent quantum yield of 0.6 - 0.8. In order to develop the study on such functionality, the compounds with the analogous skeleton were synthesized and investigated photochemically. Several substituted o-phenylenediamine reacted with oxalic acid, followed by chlorination to give the corresponding 6-substituted-2,3-dichloroquinoxalines. These intermediates were then condensed with several 2-aminopyridines, resulting in the formation of the end products, novel pyrido [1',2':1,2] imidazo [4,5-b] quinoxalines. An alternative synthetic route was also applied to prepare a wide range of the derivatives. That is, the partial amination was carried out with the 2,3-dichloroquinoxalines to afford 6-substituted-2-amino-3-chloroquinoxalines, which were treated with various substituted pyridines, including 4-phenylpyridine, 4,4'-dipyridine etc. A number of thus obtained pyridoimidazoquinoxalines were forwarded to observe the ultraviolet and fluorescent spectra, and found to exhibit the interesting fluorescent activity, some of them indicating the fluorescent quantum yield of 0.6 - 0.7. The effect of the substituents is also clarified.