α-Oxo-Iminoxyls of Isoxazolones, Pyrazol­ones and 1,2,3-Triazolone

Koch, Rainer, Wollweber, Hans-Joachim, Muller-Starke, Hans and Wentrup, Curt (2015) α-Oxo-Iminoxyls of Isoxazolones, Pyrazol­ones and 1,2,3-Triazolone. European Journal of Organic Chemistry, 2015 23: 5143-5149. doi:10.1002/ejoc.201500728


Author Koch, Rainer
Wollweber, Hans-Joachim
Muller-Starke, Hans
Wentrup, Curt
Title α-Oxo-Iminoxyls of Isoxazolones, Pyrazol­ones and 1,2,3-Triazolone
Journal name European Journal of Organic Chemistry   Check publisher's open access policy
ISSN 1434-193X
1099-0690
Publication date 2015-08
Sub-type Article (original research)
DOI 10.1002/ejoc.201500728
Volume 2015
Issue 23
Start page 5143
End page 5149
Total pages 8
Place of publication Weinheim, Germany
Publisher Wiley - V C H Verlag GmbH
Collection year 2016
Language eng
Formatted abstract
A series of α-oxo-iminoxyls was obtained by PbO2 oxidation of 4-oximinoisoxazol-5(4H)-ones, 4-oximinopyrazol-5(4H)-ones, and 1-phenyl-4-oximino-1,2,3-triazol-5(4H)-one and characterized by electron spin resonance spectroscopy in conjunction with DFT calculations of structures, energies, and hyperfine coupling constants. The iminoxyls are σ-radicals existing largely in the Z configuration with respect to the C=O group, but minor amounts of the E isomers were observable in several cases. Couplings of the free-radical electron with N1, N2, N3, C4 and C5 ring nuclei as well as the imine nitrogen N6 were observed, and some isomers were also observed to couple with a CH3 group in position 3 and with the ortho-H atoms of an aryl group in position 3. The lower energies of the Z isomers relative to the E isomers can be ascribed to a stabilizing interaction between a singly occupied orbital on the oxime oxygen and a lone pair orbital on the carbonyl oxygen.
Keyword Radicals
Nitrogen heterocycles
ESR spectroscopy
Structure elucidation
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2016 Collection
School of Chemistry and Molecular Biosciences
 
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Created: Fri, 17 Jul 2015, 09:45:50 EST by Mrs Louise Nimwegen on behalf of School of Chemistry & Molecular Biosciences