Diheteroarylmethanes. 8.<sup>1</sup> Mapping Charge and Electron-Withdrawing Power of the 1,2,4-Triazol-5-yl Substituent
作者:Alessandro Abbotto、Silvia Bradamante、Antonio Facchetti、Giorgio A. Pagani
DOI:10.1021/jo990687+
日期:1999.9.1
case of benzyl carbanion 13(-)(), all of the three nitrogen atoms are almost equally involved in delocalizing the negative charge. Also, the N-phenyl group contributes to charge delocalization. Anion 11(-)()( )()is the first of the bis(heteroaryl)methyl carbanions that we have studied, in which all of the negative charge originated by deprotonation of the carbon acid 11 is hosted on the nitrogen atoms
三个新的三唑基衍生物双(1H-1-苯基-1,2,4-三唑-5-基)甲烷(11),1H-1-苯基-5-(β-苯乙烯基)-1,2,4-合成了三唑(12)和1H-5-苄基-1-苯基-1,2,4-三唑(13)并通过多核在DMSO中研究了碳11(-)()和13(-)() NMR光谱。通过在阴离子光谱上应用先前提出并广泛使用的pi-电荷/(13)C位移关系,可以对1,2,4-三唑-5-基的pi吸电子能力进行排名电荷需求量c(X),它表示被杂环离域的pi负电荷的比例。我们的结果表明,该杂环的电荷需求c(X)远远大于其他1,3-唑类化合物(2-咪唑基,2-恶唑基,2-苯并咪唑基),与某些单-和二嗪基的电荷需求相近。取代基。碳负离子11(-)()和13(-)()均显示出一套共振,因此表明它们以单个几何异构体形式或异构体混合物的形式快速存在(在NMR时间上)规模)平衡。(13)C和(15)N位移/π电荷关系可