The Condensation of (Chlorocarbonyl)phenyl Ketene with Bisnucleophiles. Synthesis of 4-Hydroxy-5-phenylpyro-[2,3-c]pyrazol-6-ones and Formation of Pyrazolo[1,2-a]pyrazole-triones by Hydrogen Exchange in Unstable Mesoionic Compounds
作者:Mehdi Abaszadeh、Hassan Sheibani、Kazem Saidi
DOI:10.1071/ch09344
日期:——
The addition of (chlorocarbonyl)phenyl ketene 2 to 5-alkylpyrazol-3(4H)-ones 1 led to the formation of 3-hydroxypyrazolo[1,2-a]pyrazole-dione/pyrazolo[1,2-a]pyrazole-trione derivatives 3. This is ascribed to hydrogen exchange in initially formed unstable, mesoionic pyrazolo[1,2-a]pyrazol-4-ium-5-olates. In contrast, condensation of the same ketene with 3-alkyl-1-phenyl-2-pyrazolin-5-ones 4 afforded
(氯羰基)苯基乙烯酮的添加2〜5 alkylpyrazol-3(4 ħ) -酮1导致-3-羟基吡并[1,2的形成一个]吡唑二酮/吡唑并[1,2一]吡唑-三酮衍生物3。这归因于最初形成的不稳定的,中性的离子型吡唑并[1,2 - a ]吡唑-4-氧-5-酸酯中的氢交换。相反,相同的乙烯酮与3-烷基-1-苯基-2-吡唑啉-5-酮4的缩合得到4-羟基-3-烷基-1,5-二苯基吡喃并[2,3 - c ]吡唑-6-一种衍生物5。后一反应提供了新的快速途径,以高至优异的产率合成与吡唑环稠合的4-羟基-2-吡喃酮。