Papers by Viola Kolaříková
Journal of Fluorine Chemistry, Nov 1, 2016
International Journal of Molecular Sciences, Dec 2, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
International Journal of Molecular Sciences
Phenolic acids are known flavonoid metabolites, which typically undergo bioconjugation during pha... more Phenolic acids are known flavonoid metabolites, which typically undergo bioconjugation during phase II of biotransformation, forming sulfates, along with other conjugates. Sulfated derivatives of phenolic acids can be synthesized by two approaches: chemoenzymatically by 3′-phosphoadenosine-5′-phosphosulfate (PAPS)-dependent sulfotransferases or PAPS-independent aryl sulfotransferases such as those from Desulfitobacterium hafniense, or chemically using SO3 complexes. Both approaches were tested with six selected phenolic acids (2-hydroxyphenylacetic acid (2-HPA), 3-hydroxyphenylacetic acid (3-HPA), 4-hydroxyphenylacetic acid (4-HPA), 3,4-dihydroxyphenylacetic acid (DHPA), 3-(4-hydroxyphenyl)propionic acid (4-HPP), and 3,4-dihydroxyphenylpropionic acid (DHPP)) to create a library of sulfated metabolites of phenolic acids. The sulfates of 3-HPA, 4-HPA, 4-HPP, DHPA, and DHPP were all obtained by the methods of chemical synthesis. In contrast, the enzymatic sulfation of monohydroxyphenol...
ChemElectroChem, 2021
Kinetic and mechanistic aspects of an anodic oxidation of iodobenzene and its selected derivative... more Kinetic and mechanistic aspects of an anodic oxidation of iodobenzene and its selected derivatives leading to the corresponding iodosyl compounds, were investigated in anhydrous acidic acetic acid environment using boron‐doped diamond electrode. The first electron removal leading to the formation of radical cation was identified as the rate determining step of the process. Oxidation potential values of the investigated compounds were rationalised by their solution phase ionisation energies (in conformation of the radical cations as products of the first electron removal), calculated by advanced DFT methods. Unexpectedly low oxidation potential of 2‐iodobenzoic acid and its functional derivatives compared to iodobenzene, 3‐iodo and 4‐iodobenzoic acids was explained by decreased electron density at iodine atom leading to planar 2‐iodobenzoic acid radical cation. This is connected with reordering of its frontier molecular orbitals compared to non‐planar neutral molecule.
Beilstein Journal of Organic Chemistry, 2020
The prochiral 4-(allyloxy)hepta-1,6-diynes, optionally modified in the positions 1 and 7 with an ... more The prochiral 4-(allyloxy)hepta-1,6-diynes, optionally modified in the positions 1 and 7 with an alkyl or ester group, undergo a chemoselective ring-closing enyne metathesis yielding racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans. Among the catalysts tested, Grubbs 1st generation precatalyst in the presence of ethene (Mori conditions) gave superior results compared to the more stable Grubbs or Hoveyda–Grubbs 2nd generation precatalysts. This is probably caused by a suppression of the subsequent side-reactions of the enyne metathesis product with ethene. On the other hand, the 2nd generation precatalysts gave better yields in the absence of ethene. The metathesis products, containing both a triple bond and a conjugated system, can be successfully orthogonally modified. For example, the metathesis product of 5-(allyloxy)nona-2,7-diyne reacted chemo- and stereoselectively in a Diels–Alder reaction with N-phenylmaleimide affording the tricyclic products as a mixture of two separable ...
ACS Sustainable Chemistry & Engineering, 2018
As a novel approach to the separation of polyfluorinated compounds, we disclosed that HFE 7100 (m... more As a novel approach to the separation of polyfluorinated compounds, we disclosed that HFE 7100 (methyl perfluorobutyl ether) forms with alkanes or chlorinated solvents two-layer systems between −51 and 30°C depending on the nonfluorinated solvent. Similarly, more fluorinated HFE 7500 (ethyl perfluoroisoheptan-3-yl ether) forms the corresponding two-layer systems between −42 and 79°C. While fluorinated compounds bearing 40−60% of fluorine were exclusively dissolved in the hydrofluoroether layer, nonfluorinated compounds strongly prevailed in the nonfluorinated solvent. The noncoordinating and aprotic character of the solvents used, as well as their low boiling points, enabled efficient isolation and recycling of sensitive polyfluoroalkylated Hoveyda−Grubbs second-generation precatalyst analogues. This medium fluorous method was further extended to the separation of various classes of polyfluorinated compounds including reaction intermediates, ligands, and ionic liquids. The key components of the medium fluorous separation system, hydrofluoroethers, are affordable, environmentally acceptable, and easily recyclable, as well as highly tolerable by sensitive transition-metal complexes.
Beilstein Journal of Organic Chemistry, 2015
A detailed DFT study of the mechanism of metathesis of fluoroethene, 1-fluoroethene, 1,1-difluoro... more A detailed DFT study of the mechanism of metathesis of fluoroethene, 1-fluoroethene, 1,1-difluoroethene, cis- and trans-1,2-difluoroethene, tetrafluoroethene and chlorotrifluoroethene catalysed with the Hoveyda–Grubbs 2nd generation catalyst was performed. It revealed that a successful metathesis of hydrofluoroethenes is hampered by a high preference for a non-productive catalytic cycle proceeding through a ruthenacyclobutane intermediate bearing fluorines in positions 2 and 4. Moreover, the calculations showed that the cross-metathesis of perfluoro- or perhaloalkenes should be a feasible process and that the metathesis is not very sensitive to stereochemical issues.
Dalton Transactions, 2015
Silver and palladium complexes bearing dihydroimidazolylidene or imidazolidinylidene NHC ligands ... more Silver and palladium complexes bearing dihydroimidazolylidene or imidazolidinylidene NHC ligands substituted with racemic secondary polyfluoroalkyl groups were synthesized.
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Papers by Viola Kolaříková