Electric Literature of C4H6N2OOn October 1, 2003 ,《New 1-substituted 4-cinnamoyl-5-hydroxypyrazoles and precursors thereof: Synthesis, ring closure reactions and NMR-spectroscopic investigations》 was published in Heterocycles. The article was written by Holzer, Wolfgang; Krca, Ingrid. The article contains the following contents:
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 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. The cyclocondensation of (2E)-1-[5-hydroxy-3-methyl-1-(phenylmethyl)-1H-pyrazol-4-yl]-3-phenyl-2-propen-1-one gave 3-methyl-6-phenyl-1-(phenylmethyl)-1H-pyrano[2,3-c]pyrazol-4-one, however in only 2% yield. In the experiment, the researchers used 2-Methyl-1H-pyrazol-3(2H)-one(cas: 3310-35-8Electric Literature of C4H6N2O)
2-Methyl-1H-pyrazol-3(2H)-one(cas: 3310-35-8) belongs to pyrazoles. Pyrazoles and their related multiring analogs are common elements of a wide variety of bioactive compounds. These ring structures are rare in nature. A consequence of this is that they have previously been thought to be poor moieties to include in potential new drugs. Electric Literature of C4H6N2O
Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics