Keto–enol tautomerism in β‐ketoesters: CH3C(O)CHXC(O)OY (X = H, Cl; Y = CH3, C2H5). Vibrational analyses, NMR spectra and quantum chemical calculations

Schiavoni, María Alejandra; Loreto, H.E. Di; Hermann, Angelika; Mack, Hans‐Georg; Ulic, Sonia E.; Védova, Carlos O. Della

doi:10.1002/jrs.701

Cited by 30 publications

(30 citation statements)

References 18 publications

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“…A slight preference for the Z‐configuration of carbonylamino hydroxypyrimidinone pharmacophore in the gas phase was observed, in coherence with the established predisposition of β‐ketoenols – a principle corner stone of this pharmacophore – to adopt the Z‐isomer in the solid state (Tchertanov and Mouscadet, ). The predisposition of aliphatic β‐ketoenols toward energetically favorable Z‐configuration has been predicted early by ab initio studies at the B3LYP/3‐G** level of theory (Schiavoni et al, ).…”

Section: Discussionmentioning

confidence: 97%

Raltegravir flexibility and its impact on recognition by the HIV‐1 IN targets

Arora¹,

Beauchêne²,

Polański

et al. 2013

J of Molecular Recognition

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HIV-1 IN is a pertinent target for the development of AIDS chemotherapy. The first IN-specific inhibitor approved for the treatment of HIV/AIDS, RAL, was designed to block the ST reaction. We characterized the structural and conformational features of RAL and its recognition by putative HIV-1 targets - the unbound IN, the vDNA, and the IN•vDNA complex - mimicking the IN states over the integration process. RAL binding to the targets was studied by performing an extensive sampling of the inhibitor conformational landscape and by using four different docking algorithms: Glide, Autodock, VINA, and SurFlex. The obtained data evidenced that: (i) a large binding pocket delineated by the active site and an extended loop in the unbound IN accommodates RAL in distinct conformational states all lacking specific interactions with the target; (ii) a well-defined cavity formed by the active site, the vDNA, and the shortened loop in the IN•vDNA complex provide a more optimized inhibitor binding site in which RAL chelates Mg(2+) cations; (iii) a specific recognition between RAL and the unpaired cytosine of the processed DNA is governed by a pair of strong H-bonds similar to those observed in DNA base pair G-C. The identified RAL pose at the cleaved vDNA shed light on a putative step of RAL inhibition mechanism. This modeling study indicates that the inhibition process may include as a first step RAL recognition by the processed vDNA bound to a transient intermediate IN state, and thus provides a potentially promising route to the design of IN inhibitors with improved affinity and selectivity.

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Section: Discussionmentioning

confidence: 97%

Raltegravir flexibility and its impact on recognition by the HIV‐1 IN targets

Arora¹,

Beauchêne²,

Polański

et al. 2013

J of Molecular Recognition

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“…C NMR spectra at room temperature, liquid MAA exists exclusively in the diketo form. 51 The crystal structure also exhibits only the diketo tautomer. 52 We calculated the two tautomeric forms of the isolated molecule, considering also different conformations.…”

Section: X-ray Photoelectron Spectroscopy Measurementsmentioning

confidence: 99%

Adsorption of Methyl Acetoacetate at Ni{111}: Experiment and Theory

et al. 2016

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Abstract. The hydrogenation of methyl acetoacetate (MAA) over modified Ni catalysts is one of the most important and best studied reactions in heterogeneous enantioselective catalysis. Yet, very little molecular-level information is available on the adsorption complex of the reactant.Here we report on a combined experimental and theoretical study of MAA adsorption on Ni{111}. XPS shows that the chemisorbed layer is stable up to 250 K; above 250 K decomposition sets in. In ultra-high vacuum conditions, multilayers grow below 150 K. DFT modelling predicts a deprotonated enol species with bidentate coordination on the flat Ni{111} surface. The presence of adatoms on the surface leads to stronger MAA adsorption in comparison with the flat surface, whereby the stabilization energy is high enough for MAA to 1 drive the formation of adatom defects at Ni{111}, assuming the adatoms come from steps.Comparison of experimental XPS and NEXAFS data with theoretical modeling, however, identify the bidentate deprotonated enol on the flat Ni{111} surface as the dominant species at 250 K, indicating that the formation of adatom adsorption complexes is kinetically hindered at low temperatures.

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“…The tautomeric equilibria for the β-diketones then favor the enol tautomers. (13) Nyquist has reported that carbon oxygen absorption band of the chelate form of β-diketones occurs in the region 1606-1620 cm -1 accompanied by much weaker absorption between 1712 and 1720 cm -1 assigned to the carbon oxygen absorption of the β-diketonate structure. (14) The FT-IR spectrum of the matrix isolated Hthd ligand is shown ECS Transactions, 2 (7) 89-104 (2007) in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…(13) The interconversion of structures B and C does not require the dissociation of the intramolecular hydrogen bond and it reduces to the migration of a proton between two oxygen atoms. Therefore it is very fast.…”

Section: Resultsmentioning

confidence: 99%

Investigation of Thermal Decomposition of the Titanium MOCVD Precursor [Ti(OPri)2(thd)2], Employing Matrix Isolation-FTIR Technique

2007

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The use of matrix isolation (MI) technique coupled with FTIR as a tool for studying the gas-phase decomposition of the metal organic chemical vapor deposition (MOCVD) precursors is demonstrated. The thermoylses experiments on the well known titanium precursor complex [Ti(OPr i ) 2 (thd) 2 ] (thd = tetramethylheptanedione) were carried out. The thermolysis was studied from ambient to 1000 °C. FTIR bands due to products could be observed from 500 °C up to 1000 °C. Intermediates like the two conformers of pivaloylketene were observed for the first time during the thermolyses of [Ti(OPr i ) 2 (thd) 2 ]. Based on the observations, the tentative mechanism involving the cleavage of metal to oxygen bond of the Hthd ligand and subsequent formation of pivaloylketene intermediates are proposed.

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Keto–enol tautomerism in β‐ketoesters: CH₃C(O)CHXC(O)OY (X = H, Cl; Y = CH₃, C₂H₅). Vibrational analyses, NMR spectra and quantum chemical calculations

Cited by 30 publications

References 18 publications

Raltegravir flexibility and its impact on recognition by the HIV‐1 IN targets

Raltegravir flexibility and its impact on recognition by the HIV‐1 IN targets

Adsorption of Methyl Acetoacetate at Ni{111}: Experiment and Theory

Investigation of Thermal Decomposition of the Titanium MOCVD Precursor [Ti(OPri)2(thd)2], Employing Matrix Isolation-FTIR Technique

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