3,5-Dichloro-4H-1,2,6-thiadiazin-4-one 1 condenses rapidly at room temperature with 1,2-diaminobenzene, 2-aminothiophenol and sodium 2-aminophenoxide to give, respectively, the purple thiadiazinoquinoxaline 4a, red thiadiazinobenzothiazine 4b and orange thiadiazinobenzoxazine 4c in almost quantitative yield. The 10H tautomer 4a is spectroscopically almost identical with the purple 10-methyl derivative 11 formed by condensation of 1 with N-methyl-1,2-diaminobenzene and by the methylation of 4a. The chlorine substituent in these tricyclic thiadiazino compounds is readily displaced by nucleophiles, to give the 4-ethoxy 13 and 4-piperidino derivative 21. The dicyanomethylene compound 2, analogous to 1, reacts in the same way as 1 with 2-aminothiophenol to give 4b (87%), but its reaction with 1,2-diaminobenzene is more complex since, in addition to the analogous formation of 4a, there is now the possibility of another cyclisation in the intermediate 16 which leads to the tetracyclic compound 14 and its substitution product 15. This difference in reaction pathway between 1 and 2 is further illustrated by their condensation with 1,8-diaminonaphthalene: 1 is converted into 19 by simple displacement of chlorine, whilst 2 gives, almost quantitatively, the product 20 of cyclisation onto the neighbouring cyano group.
3,5-二
氯-4H-1,2,6-噻二嗪-4-酮1在室温下与1,2-二
氨基苯、2-
氨基
噻吩酚和钠盐2-
氨基苯氧化物迅速缩合,分别生成紫色的噻二嗪
喹啉4a、红色的噻二嗪苯并
噻嗪4b和橙色的噻二嗪苯并噁嗪4c,产率几乎是定量的。10H互变异构体4a在光谱上与通过与
N-甲基-1,2-二
氨基苯的缩合反应和对4a的甲基化反应生成的紫色10-甲基衍
生物11几乎相同。这些
三环噻二嗪化合物中的
氯取代基可以被亲核试剂轻易取代,生成4-乙氧基衍
生物13和4-
哌啶基衍
生物21。与1类似的二
氰甲烯化合物2与2-
氨基
噻吩酚的反应与1相似,生成4b(87%),但与1,2-二
氨基苯的反应更为复杂,除了类似于4a的反应,现在还可能在中间体16中发生另一个环化,导致四环化合物14及其取代产物15。1和2在反应路径上的差异通过它们与
1,8-二氨基萘的缩合进一步说明:1通过简单的
氯取代反应转化为19,而2则几乎定量生成与相邻
氰基反应的环化产物20。