1218782-26-3Relevant articles and documents
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
Abaszadeh, Mehdi,Sheibani, Hassan,Saidi, Kazem
, p. 92 - 95 (2010)
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 4-hydroxy-3-alkyl-1,5-diphenylpyrano[2,3-c]pyrazol- 6-one derivatives 5. The latter reaction provides a new and rapid route to 4-hydroxy-2-pyrones fused to pyrazole rings, in good to excellent yields.
