Conformational studies of 3-aminomethylene-2,4-pentanedione using vibrational and NMR spectra, and ab initio calculations

Gróf, Martin; Gatial, A.; Milata, Viktor; Prónayová, Naďa; Sümmchen, L.; Salzer, Reiner

doi:10.1016/j.molstruc.2006.12.023

Cited by 10 publications

(5 citation statements)

References 35 publications

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“…The presence of an intramolecular hydrogen bond was recognized as an important influence on the conformational behaviour of this type of molecules 21 . The IR, Raman and NMR spectra of 2-aminomethylene-2,4-pentanedione indicate that this compound exists as a single isomer 22 and this was also the case for the analogous structure 8c, prepared and fully characterized in this work. The reaction of o-phenylenediamine with ethoxymethylene cyanoacetate was also carried out under microwave irradiation, in the absence and in the presence of base (DBU).…”

Section: Resultssupporting

confidence: 64%

The reaction of o-phenylenediamine with ethoxymethylene compounds and aromatic aldehydes

Proença¹,

Marinho²

2010

Arkivoc

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Disubstituted o-phenylenediamines 10 were generated by reaction with ethoxymethylene malononitrile, ethyl ethoxymethylene cyanoacetate and diethyl 2-(ethoxymethylene)-malonate, followed by aromatic aldehydes. These compounds proved to be highly stable even under microwave irradiation. This feature, associated to a convenient substitution pattern, makes them suitable candidates to be tested for their biological activity or to be used as ligands for the preparation of metal complex catalysts.

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Section: Resultssupporting

confidence: 64%

The reaction of o-phenylenediamine with ethoxymethylene compounds and aromatic aldehydes

Proença¹,

Marinho²

2010

Arkivoc

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“…The same trend between the value of dipole moments and EZa:ZZa ratio has also been found in the NH 2 −CC− (COCH 3 ) 2 in vacuo study at B3LYP and MP2 levels of theory. 29 In addition, one finds a considerable variation of total dipole moments of the studied precursors with respect to the solvent effects (and/or solvent polarity). Although the dipole moment of EZa conformers is always increasing with the inclusion and/or polarity of the solvent for all studied precursors P1−P3, the dependence of the dipole moment of ZZa conformers upon the solvent inclusion/polarity do vary among the studied precursors (see Table 4).…”

Section: ■ Computational Detailsmentioning

confidence: 97%

“…The πconjugation prefers a planar structure of the push−pull systems. The planar structure is furthermore stabilized by the hydrogen bond between the amino hydrogen and the carbonyl oxygen from the acetyl 29 or methyl/ethyl ester 30 group. On the other hand, sp 3 hybridization of the amino nitrogen and the hydrogen−hydrogen repulsion prefer different nonplanar geometries.…”

Section: ■ Introductionmentioning

confidence: 99%

Conformational, Spectroscopic, and Molecular Dynamics DFT Study of Precursors for New Potential Antibacterial Fluoroquinolone Drugs

et al. 2014

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Biological activity, functionality, and synthesis of (fluoro)quinolones is closely related to their precursors (for instance 3-fluoroanilinoethylene derivatives) (i.e., their functional groups, conformational behavior, and/or electronic structure). Herein, the theoretical study of 3-fluoroanilinoethylene derivatives is presented. Impact of substituents (acetyl, methyl ester, and ethyl ester) on the conformational analysis and the spectral behavior is investigated. The B3LYP/6-311++G** computational protocol is utilized. It is found that the intramolecular hydrogen bond N-H···O is responsible for the energetic preference of anti (a) conformer (anti position of 3-fluoroanilino group with respect to the C═C double bond). The Boltzmann ratios of the conformers are related to the differences of the particular dipole moments and/or their dependence on the solvent polarity. The studied acetyl, ethyl ester, and methyl ester substituted fluoroquinolone precursors prefer in the solvent either EZa, ZZa, or both conformers equally, respectively. In order to understand the degree of freedom of rotation of the trans ethyl ester group, B3LYP/6-311G** molecular dynamic simulations were carried out. Vibrational frequencies, electron transitions, as well as NMR spectra are analyzed with respect to conformational analysis, including the effect of the substituent. X-ray structures of the precursors are presented and compared with the results of the conformational analysis.

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“…The conformations of both acetyl groups strongly depend on the possibility to create stabilizing intramolecular hydrogen bond between the electron-donor group, e.g. amino group H 2 N- (Gróf, 2007) or alkylamino group R-NH- (Gatial, 2015) and carbonyl of the cis acetyl group. The conformers with such bond belong to the most stable ones.…”

Section: Introductionmentioning

confidence: 99%

Raman and infrared spectra, conformations and ab initio calculations of 3-methoxymethylene-2,4-pentanedione

Gatial

Milata

Prónayová

et al. 2015

Acta Chimica Slovaca

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The IR (4000-400 cm-1) and Raman (4000-50 cm-1) spectra of 3-methoxymethylene-2,4-pentanedione [H3C-O-CH=C(COCH3)2] as a liquid and solutes in various solvents of different polarity have been recorded at ambient temperature. Additional IR and Raman spectra were obtained for amorphous and crystalline solid state at low temperature. The vibrational spectra revealed that the compound exists at least in two dominant conformers of different polarity and that the conformer present in the solid phase is less polar. NMR spectra in various solvents at different temperatures were also obtained. The compound can exist in several conformers due to the rotation around O-C= and both =C-C bonds with planar or nonplanar arrangements of heavy atoms. Ab initio MP2 and DFT calculations using a wide scale of basis sets were carried out. According to these calculations six conformational structures of the eight theoretically possible conformational structures with the methoxy group oriented as anti or syn and carbonyl groups oriented as Z or E towards the C=C double bond were obtained at potential energy surface. It has been shown that the conformers with the E orientations of both acetyl groups are not the stable ones. The calculated ab initio MP2 and DFT energies of all found conformers in vacuum suggest the most stable ZEa conformer where Z and E regard to the trans and cis acetyl groups, respectively and a denotes the orientation of the methoxy group. The EZa conformer was calculated as the second most stable one with the energy by at least 10 kJ mol-1 higher. Corrections of the relative energies of single conformers obtained in vacuum on the polar surroundings were done by including the solvent effect into the calculations using IEF Polarizable Continuum Model. Assignments of the vibrational spectra for the studied compound were made with the aid of normal coordinate calculations employing scaled ab initio force field. The scaled ab initio frequencies as well as calculated energies indicate that ZEa is the conformer present in the solid phase.

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Conformational studies of 3-aminomethylene-2,4-pentanedione using vibrational and NMR spectra, and ab initio calculations

Cited by 10 publications

References 35 publications

The reaction of o-phenylenediamine with ethoxymethylene compounds and aromatic aldehydes

The reaction of o-phenylenediamine with ethoxymethylene compounds and aromatic aldehydes

Conformational, Spectroscopic, and Molecular Dynamics DFT Study of Precursors for New Potential Antibacterial Fluoroquinolone Drugs

Raman and infrared spectra, conformations and ab initio calculations of 3-methoxymethylene-2,4-pentanedione

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