1-(1-乙基-1H-5-吲哚基)-2-苯基-1,2-二酮缩合成1,2,4-三嗪类化合物反应

Condensation of 1-(1-Ethyl-1H-indol-5-yl)-2-phenylethane-1,2-dione to 1,2,4-Triazines

报道了一种1-（1-乙基-1H-5-吲哚基）-2-苯基-1,2-二酮与氨基胍碳酸氢盐缩合生成互为同分异构体的两种1,2,4-三嗪的反应,并通过运用目标定向合成和核磁的方法,研究了1,2-二酮苯环上不同取代基对反应产品比例的影响.反应总收率为40%~81%,且当不对称1,2-二酮苯环上无取代基时,其生成的同分异构体6-（1-乙基-1H-5-吲哚基）-5-苯基-3-氨基-1,2,4-三嗪（2a）和5-（1-乙基-1H-5-吲哚基）-6-苯基-3-氨基-1,2,4-三嗪（4a）比例为40∶60;当苯环上取代基为吸电子基时,6-（1-乙基-1H-5-吲哚基）-5-（4-硝基苯基）-3-氨基-1,2,4-三嗪（2b）和5-（1-乙基-1H-5-吲哚基）-6-（4-硝基苯基）-3-氨基-1,2,4-三嗪（4b）比例为63∶37;当苯环上取代基为供电子基时,绝大部分生成2系列构型结构.

This paper reports the selective condensation of aminoguanidine with 1-（1-ethyl-1H-indol-5-yl）-2-phenylethane-1,2-dione to afford 1,2,4-triazines. The constituents and relative proportion of these condensation products are identified by the methods of target-oriented synthesis and nuclear magnetic resonance. And the influences on the relative proportion by different substituents are described. When the phenyl is substituted with the electron-withdrawing group, the ratio of the isomers 6-（1-ethyl-1H-indol-5-yl）-5-phenyl-1,2,4-triazin-3-amine/5-（1-ethyl-1H-indol-5-yl）-6-phenyl-1,2,4-triazin-3-amine [n（2a） ∶n（4a）] is 40 ∶ 60; when without the substituent, the ratio of the isomers 6-（1-ethyl-1H-indol-5-yl）-5-（4-nitrophenyl）-1,2,4-triazin-3-amine/5-（1-ethyl-1H-indol-5-yl）-6-（4-nitrophenyl）-1,2,4-triazin-3-amine [n（2b）∶n（4b）] is 63∶37; when substituted with the electron-donating group, the type of the major products was 2.