On the mechanism of the generation of 5-oxy-2,3-dihydroimidazo[1,2-a]pyrazin-3-ones by the direct variable-temperature NMR method: a variable-temperature study
作者:Katsunori Teranishi、Makoto Hisamatsu、Tetsuya Yamada
DOI:10.1039/a608462a
日期:——
The mechanism of the generation of
8-benzyl-2-(tert-butyl)-6-(p-methoxyphenyl)-5-oxy-
2,3-dihydroimidazo[1,2-a]pyrazin-3-ones 2a, 2b and 2c from
3-benzyl-2-[1-(2-trimethylsilylethoxycarbonyl)-2,2-
dimethylpropylideneamino]-5-(p-methoxyphenyl)pyrazine 1 has
been investigated. The structure of an unstable intermediate 4 forming
2a, 2b and 2c in the reactions has been proved to have a
2-(methoxycarbonyloxy)-2,3-dihydroimidazo[1,2-a]pyrazin-3-one
ring system by the results of direct variable-temperature
1
H
NMR spectral analysis, low-temperature
13
C NMR and 2D NMR
(
1
H–
13
C COSY and COLOC) spectral analysis of
the crude reaction mixture.
从3-苄基-2-[1-(2-三甲基硅乙氧基羰基)-2,2-二甲基亚丙基氨基]-5-(对甲氧基苯基)吡嗪1中生成8-苄基-2-(叔丁基)-6-(对甲氧基苯基)-5-氧代-2,3-二氢咪唑并[1,2-a]吡嗪-3-酮2a、2b和2c的机理已得到研究。通过直接可变温度1H NMR光谱分析、低温13C NMR和2D NMR(1H-13C COSY和COLOC)对反应混合物进行光谱分析的结果,证明在反应中形成2a、2b和2c的不稳定中间体4的结构具有2-(甲氧羰基氧基)-2,3-二氢咪唑并[1,2-a]吡嗪-3-酮3-酮环系统。