Cyclization of Isothiosemicarbazones. IV. Synthesis of the [1,2,4]Triazolo[1,5-<i>c</i>]pyrimidine Ring System
作者:Chiji Yamazaki
DOI:10.1246/bcsj.54.1767
日期:1981.6
Condensation of isothiosemicarbazones with ethoxymethylenemalononitrile gave 2,3-dihydro[1,2,4] triazolo[1,5-c]pyrimidines in moderate to high yields. The 2,3-dihydro compounds were readily oxidized in dimethyl sulfoxide to give the corresponding [1,2,4]triazolo[1,5-c]pyrimidines.
A novel route to 1-benzyl-1,2,4-triazole derivatives through disproportionation of isothiosemicarbazones
作者:Chiji Yamazaki、Mariko Ohno
DOI:10.1002/jhet.5570340305
日期:1997.5
Aromatic isothiosemicarbazones 1–4 underwent disproportionation at elevated temperature in the presence of a thiol or a thiol-releasing substance to give 1-arylmethylene-3-alkylthio-5-aryl-1H-1,2,4-triazole derivatives 6–9 in moderate yields. An isothiosemicarbazone of aliphatic aldehyde with no α-hydrogen did not give rise to the corresponding disproportionation under the similar conditions. Cross reaction
在高温下,在有硫醇或释放硫醇的物质下,芳族异硫代半碳杂唑烷1-4歧化,得到1-芳基亚甲基-3-烷基硫基-5-芳基-1 H -1,2,4-三唑衍生物6-9产量中等。在类似条件下,没有α-氢的脂族醛的异亚氨基脲也不会引起相应的歧化。在两个不同的异硫代咪唑酮之间发生了交叉反应,但只能以较低的收率分离出交叉化合物。任何惰性溶剂都可以显着抑制歧化反应,即使仅将其稀释即可。提出了一个初步的反应机理,其中可能涉及潜在的氮烯-ulf离子对作为关键步骤。