Search results for "Phenacyl"
showing 6 items of 6 documents
Predominance of inductive over resonance substituent effect on33S NMR chemical shifts of 4-substituted phenyl-4′-methylphenacyl sulfones
1999
33S NMR chemical shifts have been determined for the first time for a series of 10 substituted phenacyl sulfones. Electron-withdrawing and electron-releasing substituents in 4-substituted phenyl-4′-methylphenacyl sulfones, p-MeC6H4COCH2SO2C6H4R-p, cause a ‘reverse’ substituent effect on the 33S NMR resonance. Dual-substituent parameter (DSP) analysis of δ(33S) values revealed that the inductive effect of the substituent predominates over its resonance effect. This finding shows that the 33S NMR chemical shifts are of importance in estimating the electronic properties of sulfur-containing compounds. The 13C and 17O NMR chemical shifts of the title compounds are also discussed. Copyright © 19…
Synthesis of 4(5)-phenacyl-imidazoles from isoxazole side-chain rearrangements
2010
A novel base-induced rearrangement of isoxazoles into imidazole derivatives is reported. In the isoxazole series, this represents the first example of a three-atom side-chain rearrangement involving a CNC sequence. The reactions are carried out under nitrogen and produced 2-aryl-4(5)-phenacyl-5(4)-phenyl-imidazoles in high yields. In the presence of oxygen, a cascade rearrangement-oxidation reaction sequence was observed and imidazole derivatives bearing an oxidized side-chain were isolated.
On the rearrangement of some Z-arylhydrazones of 3-benzoyl-5-phenylisoxazoles into 2-aryl-4-phenacyl-2H-1,2,3-triazoles: a kinetic study of the subst…
2015
Abstract The rearrangement of eight new Z -arylhydrazones of 3-benzoyl-5-phenylisoxazoles ( 3d – k ) into the relevant 2-aryl-4-phenacyl-2 H -1,2,3-triazoles ( 4d – k ) in dioxane/water solution at different proton concentrations has been quantitatively studied in a wide temperature range (293–333 K). The data collected together with some our previous ones on compounds 3a – c have allowed a deep study of the substituent effects on the course of the rearrangement, thus increasing our knowledge on the Boulton–Katritzky reactions in isoxazole derivatives and on the temperature effects on free energy relationships.
ChemInform Abstract: Synthesis of 4(5)-Phenacyl-imidazoles from Isoxazole Side-Chain Rearrangements.
2011
The reaction must be carried out under nitrogen atmosphere in deoxygenated solvent to prevent the oxidation of the imidazole products.
Synthesis and Structural Characterization of Substituted 2-Phenacylbenzoxazoles
2013
1 H and 13C NMR spectra of eleven 2-phenacylbenzoxazoles (ketimine form) show that their CDCl3-solutions contains also (Z)-2-(benzo[d]oxazol-2-yl)-1-phenylethenols (enolimine form). Intramolecular hydrogen bonding in the latter tautomer was found to be significantly weaker than that one in respective (Z)-2-(2-hydroxy-2-phenylvinyl)pyridines. Integrals of the 1 H NMR signals were used to evaluate the molar ratio of the tautomers. Strong electron-donating substituents were found to stabilize the ketimine tautomer. pKT (negative logarithm of the equilibrium constant, KT = [ketimine]/[enolimine]) was found to be linearly dependent on the Hammett substituent constant σ. The results of the MP2 ab…
Unprecedented ring cleavage in the reaction of 1-methyl-3-phenacyl benzimidazolium ylide with diethyl azodicarboxylate
2010
The reaction with diethyl azodicarboxylate (DEAZD) of different cycloimmonium ylides derived from pyridinium, quinolinium, isoquinolinium and 1-methylbenzimidazolium bromides (3, 4, 5 and 6) yielded 3-substituted tetraazapentenes (2). In the special case of 1-methyl-3-phenacyl-benzimidazolium bromide (6a), the ring cleavage compound N-[1-[(ethoxycarbonyl)amino]-2-oxo-2-phenylethylidene]-N-formyl-N-methyl-1,2-benzenediamine (7a) was obtained. Its structure was established by X-ray crystallography.