- THE (1)H AND (13)C N.M.R. RULES FOR THE ASSIGNMENT OF 1,3- AND 1,5-DISUBSTITUTED PYRAZOLES: A REVISION
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The H-5 signal of N-substituted pyrazoles is not shifted to low field values on increasing solvent polarity when a nitrogen lone pair lies very close to the measured proton (H-bond).Typical examples of this "abnormal" behaviour are provided by C,N'-linked, pyrazole-containing heterocyclic dimers.On the contrary, models selected in the 1,1'-bipyrazole and 2,2'-biindazole series (N,N'-linkage) showed normal shifts, due to their non-coplanar conformation around the N-N bond.For the assignment of disubstituted pyrazoles, a proton-coupled (13)C n.m.r. spectrum is recommended as an alternative method.
- Bruix, Marta,Mendoza, Javier de,Elguero, Jose
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- Metallosupramolecular architectures based upon new 2-(1-pyrazolyl)-benzimidazole chelating ligands
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In this article, we report the synthesis and characterisation of five ligands L1-L5 containing the 2-(pyrazol-1-yl)-benzimidazole chelating group, and investigate their structural chemistry when reacted with either Cu(II) or Zn(II) ions. The mononuclear c
- Hawes, Chris S.,Kruger, Paul E.
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p. 757 - 771
(2015/12/30)
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- Direct, metal-free amination of heterocyclic amides/ureas with NH-heterocycles and N-substituted anilines in POCl3
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A POCl3-mediated, direct amination reaction of heterocyclic amides/ureas with NH-heterocycles or N-substituted anilines is described. Compared to the existing methods, this operationally simple protocol provides unique reactivity and functional
- Deng, Xiaohu,Roessler, Armin,Brdar, Ivana,Faessler, Roger,Wu, Jiejun,Sales, Zachary S.,Mani, Neelakandha S.
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experimental part
p. 8262 - 8269
(2011/12/04)
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