The Structure of 4‐Benzoyl‐5‐methyl‐2‐phenylpyrazol‐3‐one Oxime and Its Methyl Derivatives

Abstract

Keywords: Oximes / Tautomerism / X-ray diffraction / NMR spectroscopy / Density functional calculations 1 H and 13 C NMR spectroscopic investigations of 4-benzoyl-5-methyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one oxime (4) and different methylation products thereof (5−11) indicate that 4 exists predominantly as 4-enaminopyrazolone in [D 6 ]DMSO solution. Single-crystal X-ray analysis revealed that in the solid state the same tautomeric structure of 4 was present, and closely resembles that of the corresponding N-

Synthesis, spectral, thermal and crystallographic investigations on oxovanadium(IV) and manganese(III) complexes derived from heterocyclic β-diketone and 2-amino ethanol

“…This is most probably due to the steric repulsion between carbonyl group and phenyl ring (C14 through C9) [29]. It is worth noting that the C5-N1 bond distance value of 1.303(2) Å is falling into the C=N double bond distance region, also, in pyrazolone exocycle, the C3-O3 bond distance of 1.259(2) Å as well as the C7-C4 bond distance of 1.382(2) Å are showing the value of C=O and C=C double bond character, respectively [29] These indicate that the title compound mainly exists in amine-one form [10][11][12] (Fig. 2).…”

“…The HL 1 is stabilized by intra-molecular hydrogen bonds rather than the imine-ol form. In order to form the more stable conformation stabilized by intra-molecular hydrogen bond, the π -electron between C-N (C7-C8) will be delocalize to C7-C4 bond [11,28]. This is confirmed by the crystallographic observation; N-H· · ·O hydrogen bonded ring (O3, C3, C4, C7, N8, H8) is coplanar with the pyrazole ring, with an N8-C7-C4-C3 torsion angle of 3.7(3) • .…”

“…(9)(10)(11) and the results are described in (Tables 7 and 8). All the powder samples were recorded in quartz tubes to avoid Mn(II) or Fe(II) impurities and solution spectra were recorded in 60:40 (DMF + pyridine) mixed solutions in capillary tube.…”

“…Pyrazolone derivatives are also used as starting materials for the synthesis of biologically active compounds [7] and for the construction of condensed heterocyclic systems [8,9]. Moreover, particular interest was drawn due to the ability of these compounds existing in several tautomeric forms, such as CH, OH and NH [10][11][12][13][14][15]. Variations in the design and synthesis of such O 2 -donors have been developed in the recent years, to induce different behaviour and properties in the corresponding metal derivatives [16].…”

Oximes of five-membered heterocyclic compounds with two heteroatoms. 1. Synthesis and structure (Review)

“…The structures of the oximes of 1-(4-fluorophenyl)-2-[5-(4-fluorophenyl)-4,5-dihydro-3-isoxazolyl]-ethanone [134], 1,2-benzoisothiazol-3-yl methyl ketone [156], and 4-benzoyl-5-methyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one [157], 1-(4-chlorophenyl)-4-phenyl-2,5-dihydro-1H-imidazol-2-ylphenylmethanone oxime 3-oxide [158], 2-(imidazol-1-yl)-1-(2-naphthyl)-ethanone O-(2-propene)oxime hydrochloride [159], and 6-{[(hydroxyimino)phenyl]methyl}-1-[(1-methylethyl)sulfonyl]-1H-benzimidazole-2-amine [145] were also confirmed by X-ray crystallographic analysis.…”