An efficient and chemoselective method for oximination of β-diketones under mild and heterogeneous conditions
A combination of oxalic acid dihydrate and sodium nitrite in the presence of wet SiO2 was used as an effective nitrosating agent for the nitrosation of β-diketones to their corresponding α-oximinoketones in moderate to excellent yields under mild and heterogenous conditions.
Metal-Free Sequential C(sp2)-H/OH and C(sp3)-H Aminations of Nitrosoarenes and N-Heterocycles to Ring-Fused Imidazoles
Hydrogen bond assisted ortho-selective C(sp2)-H amination of nitrosoarenes and subsequent α-C(sp3)-H functionalization of aliphatic amines is achieved under metal-free conditions. The annulation of nitrosoarenes and 2-hydroxy-C-nitroso compounds with N-heterocycles provides a facile excess to a wide range of biologically relevant ring-fused benzimidazoles and structurally novel polycyclic imidazoles, respectively. Nucleophilic aromatic hydrogen substitution (SNArH) was found to be preferred over classical SNAr reaction during the C(sp2)-H amination of halogenated nitrosoarenes.
Purkait, Anisha,Roy, Subhra Kanti,Srivastava, Hemant Kumar,Jana, Chandan K.
supporting information
p. 2540 - 2543
(2017/05/24)
Synthesis and study of prototropic tautomerism of 2-(3-chromenyl)-1- hydroxyimidazoles
A series of novel derivatives of imidazole containing a chromenyl moiety in position 2 of the ring has been synthesized. A characteristic response of the chromenyl ring H-2 proton to its environment allows the study of the prototropic tautomerism of novel 1-hydroxyimidazoles in solution using 1H NMR spectroscopy. It has been shown that the predominance of one or another tautomer depends on the nature of the substituents of the imidazole ring, and the proton-donating/proton-withdrawing properties of a solvent. X-ray diffraction data for two of the compounds has revealed that in the solid state these 1-hydroxyimidazole derivatives exist as N-oxide tautomers.
Nikitina, Polina A.,Kuz'Mina, Ludmila G.,Perevalov, Valery P.,Tkach, Iosif I.
p. 3249 - 3256
(2013/05/09)
Silica sulfuric acid/NaNO2 as a novel heterogeneous system for the chemoselective α-nitrosation of β-diketones under mild conditions
A combination of silica sulfuric acid and sodium nitrite in the presence of wet SiO2 was used as an effective nitrosating agent for the nitrosation of β-diketones to their corresponding α-nitroso or α-oximinoketones under mild and heterogenous conditions in moderate to excellent yields.
Zolfigol, Mohammad Ali,Ghorbani Choghamarani, Arash
p. 1623 - 1629
(2007/10/03)
182. Heterocyclic Rearrangement of 4,5,6,7-Tetrahydro-6,6-dimethylbenzooxadiazol-4-one (Z)-Arylhydrazones into Corresponding 2-Aryl-4,5,6,7-tetrahydro-2H-benzotriazol-4-one Oximes
The thermal base-catalysed and photochemical transformation (Boulton-Katritzky rearrangement) of the title tetrahydrobenzooxadiazoles to tetrahydro-2H-benzotriazoles is studied.Attempts to induce analogous rearrangement in tetrahydro-2H-benzotriazol-4-one arylhydrazones or oximes failed.Some CNDO/2 calculations are also carried out.
Lefkopoulou, Susan,Stephanidou-Stephanatou, Julia,Tsoleridis, Constantine,Alexandrou, Nicholas E.
p. 1748 - 1753
(2007/10/02)
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