635288-46-9Relevant articles and documents
Synthesis of some pyrano[2,3-c]pyrazoles
Pavlik, James W.,Ervithayasuporn, Vuthichai,Tantayanon, Supawan
scheme or table, p. 710 - 714 (2011/07/31)
Synthetic methods have been developed to prepare pyrano[2,3-c]pyrazoles with various substituents at ring positions 1, 3, and 6. The 1H- and 13C-NMR properties of these products and their precursors are presented and discussed.
New 1-substituted 4-cinnamoyl-5-hydroxypyrazoles and precursors thereof: Synthesis, ring closure reactions and NMR-spectroscopic investigations
Holzer, Wolfgang,Krca, Ingrid
, p. 2323 - 2342 (2007/10/03)
Reaction of 1-substituted 5-hydroxy-1H-pyrazoles (pyrazolones) with trans-cinnamoyl chloride / calcium hydroxide in dioxane affords the corresponding 4-cinnamoyl-5-hydroxy-1H-pyrazoles. Cyclization of the latter into 5,6-dihydropyrano[2,3-c]pyrazol-4-ones proceeds in very low yields upon treatment with concentrated sulfuric acid. 1,6-Diphenyl-1H-pyrano[2,3-c]pyrazol-4-one was synthesized by reaction of of 4-acetyl-5-hydroxy-1-phenyl-1H-pyrazole with benzoyl chloride and lithium bis(trimethylsilyl)amide and subsequent cyclization of the thus obtained 1,3-diketone. NMR-spectroscopic investigations with the obtained 4-substituted 5-hydroxypyrazoles and their precursors regarding their tautomeric behavior in various solvents are presented.
