136229-98-6Relevant academic research and scientific papers
Stereochemical Effects in the Nitrosation of Some α,β-Unsaturated Ketoximes. Formation of 1-Hydroxypyrazole 2-Oxides and 4-Oximino-4,5-dihydroisoxazoles
Hansen, John F.,Easter, John A.
, p. 1481 - 1486 (2007/10/02)
Several α,β-unsaturated ketoximes R1CH=CHC(=NOH)R2 were nitrosated using butyl nitrite in aqueous ethanol in the presence of copper(II) sulfate and pyridine.The product distribution varied depending on whether the oxime hydroxyl group was syn or anti with respect to the carbon-carbon double bond.The anti-oximes gave the copper complexes of 1-hydroxypyrazole 2-oxides in high yields.The isomeric syn-oximes gave lower yields of the pyrazole complexes along with 4-oximino-4,5-dihydroisoxazole derivatives.For the syn-oximes where R1 is phenyl and R2 is either methyl or ethyl, conversion of the oximes to the parent ketones was also observed.The results may be explained by processes involving N-nitrosonitrone intermediates.
Nitrosation of Methyl and Phenyl Styryl Ketoximes Under Oxygen. Formation of 4-Nitro-1-hydroxypyrazole 2-Oxides and 3,5-Diphenyl-4-nitrato-4,5-dihydroisoxazole
Hansen, John F.,Georgiou, Paul J.
, p. 1487 - 1492 (2007/10/02)
The nitrosation of the oximes of 4-phenyl-3-buten-2-one and 1,3-diphenyl-2-propen-1-one under oxygen has been reinvestigated.In addition to 4-oxo- and 4-oximino-4H-pyrazole 1,2-dioxides previously reported, the reactions give 4-nitro-1-hydroxypyrazole 2-oxides.In the case of 1,3-diphenyl-2-propen-1-one oxime the nitrosation reaction also gives 3,5-diphenyl-4-nitrato-4,5-dihydroisoxazole.Evidence is presented suggesting that the nitrate ester is formed through the rearrangement of a peroxynitrite intermediate.
Preparation of 4-Bromo-1-hydroxypyrazole 2-Oxides by Nitrosation of α-Bromo-α,β-unsaturated Ketoximes
Hansen, John F.,Easter, John A.,Eckert, David A.,Hunt, Karen J.,Little, David A.
, p. 281 - 286 (2007/10/02)
Nitrosation of the oximes of 3-bromo-3-penten-2-one, 3-bromo-4-phenyl-3-buten-2-one, and 2-bromo-1,3-diphenyl-2-propen-1-one using sodium nitrite in acetic acid gave low yields of 4-pyrazolone 1,2-dioxides.Nitrosation using butyl nitrite in the presence of copper(II) sulfate and pyridine in aqueous ethanol produced insoluble copper complexes from which 3,5-dimethyl-, 3-methyl-5-phenyl-, and 3,5-diphenyl-4-bromo-1-hydroxypyrazole 2-oxides could be liberated by treatment with dilute potassium hydroxide, filtration, and acidification of the filtrate.High yields wereobtained with the first two oximes, but, presumably due to unfavorable stereochemistry of the oxime, the diphenyl derivative gave a lower yield of the complex, accompanied by 4-bromo- and 4-nitro-3,5-diphenylisoxazole and 4-oximino-3,5-diphenyl-4,5-dihydroisoxazole.
Synthesis of some new 1-hydroxypyrazole-2-oxides and heterocyclic oximes
Fadda, A. A.
, p. 749 - 753 (2007/10/02)
α,β-Unsaturated oximes (Ia-c) are converted into 1-hydroxypyrazole-2-oxides (IIIa-c) and isoxazole (IV) by reaction with n-butyl nitrite and metal ions in pyridine.Reduction of IIIc with zinc in acetic acid furnishes the pyrazole V.However, reduction of IIIc with sodium dithionite yields the 1-hydroxypyrazole (VI).Acylation of IIIc affords the acyl derivative (VII).Reaction of hydroxylamine hydrochloride and benzaldehyde with oximes VIIIa,b and IXa,b affords O-methyloximinoisoxazoles (Xa,b).
