4-Iminobarbiturates: Tautomerism and electrochemical behavior in relation to N(3) substitution.
作者:CHRISTOPHE GIRAUD、CLAIRE GUEUTIN、OLIVIER LAFONT、MICHEL GUERNET、MARCEL MIOCQUE
DOI:10.1248/cpb.36.563
日期:——
Tautomerism of 4-iminobarbiturates depends upon the presence of a substituent on the N(3)atom. The ultraviolet, infrared, proton nuclear magnetic resonance, 13C-nuclear magnetic resonance and mass spectrum data show that 3-alkylated compounds present an imido system while 3-unalkylated ones are characterized by an amidinoketone system.The electrochemical bahavior of these two groups was studied by polarography, cyclic voltammetry and controlled potential electrolysis in dipolar aprotic solvents (dimethyl sulfoxide and hexamethyl phosphoric triamide), and was found to be related to the structure : the reduction of 3-substituted compounds is more difficult (about 0.2 V) than the reduction of 3-unalkylated products. The monoelectronic mechanism of this reduction was determied and confirmed by the electrochemically induced formation of an anion which can be alkylated using methyl iodide.
4-iminobarbiturates 的同分异构体取决于 N(3)原子上是否存在取代基。紫外线、红外线、质子核磁共振、13C 核磁共振和质谱数据显示,3-烷基化化合物呈现亚氨基体系,而 3-非烷基化化合物则以脒基酮体系为特征。通过极谱法、循环伏安法和在双极性非丙烷溶剂(二甲亚砜和六甲基磷酰三酰胺)中的受控电位电解法研究了这两个基团的电化学行为,发现它们与结构有关:3-取代型化合物的还原比 3-非烷基化产物的还原更困难(约 0.2 V)。电化学诱导形成的阴离子可使用甲基碘进行烷基化,从而确定并证实了这种还原的单电子机制。