Rearrangement of 3,3-Disubstituted 1-Aryl-4,5-dihydro-5-oxo-3<i>H</i>-1,2,4-triazolium Tetrafluoroborates; Part 3. An Efficient Synthesis of 1,5-Heteroannulated 1,2-Dihydro-2-phenyl-3<i>H</i>-1,2,4-triazol-3-ones
作者:Hubert Gstach、Patrick Seil
DOI:10.1055/s-1990-27090
日期:——
1-Isocyanato-1-(phenylazo)heterocycloalkanes 3a-f react with tetrafluoroboric acid to yield the respective 3-spiro-substituted 4,5-dihydro-5-oxo-1-phenyl-3H-1,2,4-triazolium tetrafluoroborates 4a-f. These compounds rearrange under ring enlargement in good yields to 1,5-heteroannulated 1,2-dihydro-2-phenyl-3H-1, 2,4-triazol-3-ones 5a-f. In two special cases, 4,5-heteroannulated 2,4-dihydro-2-phenyl-3H-1,2,4-triazol-3-ones 7g,h are obtained.
1-Isocyanato-1-(phenylazo)heterocycloalkanes 3a-f 与四氟硼酸反应,生成相应的 3-螺取代的 4,5-二氢-5-氧代-1-苯基-3H-1,2,4-三唑四氟硼酸盐 4a-f。这些化合物在扩环作用下重新排列,生成 1,5-杂环 1,2-二氢-2-苯基-3H-1,2,4-三唑-3-酮 5a-f。在两种特殊情况下,可得到 4,5-杂环 2,4-二氢-2-苯基-3H-1,2,4-三唑-3-酮 7g,h。