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1
Content available Thermal [3+2] cycloaddition reactions as most universal way for the effective preparation of five-membered nitrogen containing heterocycles
Kras Jowita, Sadowski Mikołaj, Zawadzińska Karolina, Nagatsky Roman, Woliński Przemysław, Kula Karolina, Łapczuk Agnieszka
Scientiae Radices
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2023
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Vol. 2, Iss. 3
247--267
EN
The possibility of the construction of five-membered heterocycles, including single heteroatom or systems with two, three and four heteroatoms were critically reviewed based on the recent reports regarding to the [3+2] cycloaddition reactions. Almost all of analysed reaction are realized with high regio- and stereoselectivity.
2
Content available Reakcja Mitsunobu : mechanizm i zastosowanie
Kitkowska J. D., Tabaczyńska Ż. A., Dramiński M.
Wiadomości Chemiczne
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2013
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[Z] 67, 9-10
843--876
EN
The Mitsunobu reaction has been known since 1967, but the research on its modifications as well as on the introduction of new reagents, productivity, improvement and methods of post-reaction mixture separation is still being conducted. The original reaction was used to obtain esters by condensation of carboxylic acids and alcohols using triphenylphosphine and DEAD mixture. This reaction allows formation of s not only carbon-oxygen bond, but also carbon-carbon, carbon-nitrogen, and carbon-sulphur to be synthesized. The Mitsunobu reaction is widely applied in organic synthesis as a way of inversion of configuration of secondary alcohols or of aryl ethers synthesis. Numerous studies bring the accounts of using this reaction for the synthesis of steroids, carbohydrates, nucleosides, as well as alkaloids and other heterocyclic compounds containing nitrogen. The popularity of this reaction lies in its stereoselectivity and compatibility with a wide range of functional groups as well as in its moderate requirements considering reaction conditions. However, an isolation of a desirable product from the used up or surplus reagents still causes a lot of difficulties.
3
Content available remote Zależności pomiędzy stereoselektywnością i szybkością reakcji a polarnością cieczy jonowych
Janus E., Wróblewska E. K.
Przemysł Chemiczny
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2013
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T. 92, nr 9
1610-1614
PL
Zbadano reakcję Dielsa i Aldera pomiędzy cyklopentadienem i maleinianem dimetylu w cieczach jonowych zbudowanych z anionu NTf2- i różnych kationów. Wartości stałej szybkości i stereoselektywności endo:egzo skorelowano z parametrami polarności Kamleta i Tafta i lepkością cieczy jonowych. Zastosowanie wielowymiarowej regresji liniowej pozwoliło ustalić, że właściwości protonodonorowe, związane z parametrem polarności α oraz lepkość cieczy jonowej mają największy wpływ na stałą szybkości reakcji. Natomiast polaryzowalność, związana z parametrem π* przyczynia się w dużym stopniu do zmian stereoselektywności, podczas gdy zdolności do donacji i akceptacji protonu są mniej ważne.
EN
Eleven ionic liqs. were used as medium of the Diels-Alder reaction between cyclopentadiene and dimethyl maleate carried out at 25°C to det. reaction rate constants and stereoselectivities correlated with Kamlet-Taft polarity parameters and viscosity of the ionic liqs. Multidimensional linear regression model was chosen. The H bond donating ability and viscosity of ionic liqs. had a significant impact on the reaction rate const. Polarizability contributed to a large extent to the changes in stereoselectivity, whereas H bondaccepting and donating abilities were of lesser importance.
4
Content available remote Regio- i stereoselektywność [2+3] cykloaddycji α-podstawionych nitroetenów z 1,3-dipolami propargilo-allenowego i allilowego typu
Jasiński R., Mikulska M., Socha J., Barański A.
Czasopismo Techniczne. Chemia
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2012
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R. 109, z. 2-Ch
53--63
PL
W artykule przeprowadzono krytyczną analizę danych literaturowych dotyczących regioi stereoselektywności reakcji [2+3] cykloaddycji z udziałem α-podstawionych nitroetenów.
EN
The paper is a critical review of available literature data about regio- and stereoselectivity of [2+3] cycloaddition reactions of α-substituted nitroethenes.
5
Uptake of Molecular Oxygen by Co(II) Chelates with Peptides in Aqueous Solution. Part XII. Non-covalent Interactions in the Cobalt(II) - Diastereoisomeric Phenylalanyl Dipeptide Systems. Effect on Kinetics of Oxygenation
Kufelnicki A., Świątek A.
Polish Journal of Chemistry
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2008
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Vol. 82, nr 5
981-991
EN
The interactions of Co(II) with a group of diastereoisomeric dipeptides containing a side chain with the aromatic phenyl ring have been studied in aqueous solution, both under inert atmosphere and in the presence of dioxygen. An effect of stereoselectivity has been observed in the metal promoted deprotonations, examined by glass electrode potentiometry and correlated with the results of UV/Vis spectroscopy. The kinetics of oxygenation were studied by the stopped flow method and related to the potentiometric results.
6
Uptake of molecular oxygen by Co(II) chelates with peptides in an aqueous colution : Part XI : Stereoselective properties of oxygenated diastereoisomeric dipeptide systems
Kufelnicki A., Świątek M.
Polish Journal of Chemistry
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1999
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vol. 73 nr 4
579-591
EN
The reaction of oxygen uptake by Co(II) complexes with a group of diastereoisimetric dipeptides, consisting of alanine and leucine in various chiral forms, has been studied in an aqueous solution. The structure of the bridging moiety has been discussed on the basis of spectroscopic results (UV, Vis, near IR, CD, ESR). The effect of stereoselectivity has been confirmed by studies of reversibility of oxygenation. Comparative ESR measurements were done for mixed complexes with imidazole as N-base in the axial position. All of the results were compared with that for glycine dipeptides (containing only one asymmetric atom).
7
Synthesis and Properties of Azoles and Their Derivatives : Part XLI : Stereoselectivity and Kinetic Study of the [2+3]Cycloaddition of E-B-Nitrostyrene to Z-C,N-Diphenylnitrone
Barański A.
Polish Journal of Chemistry
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1999
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Vol. 73, nr 10
1711-1717
EN
Stereoselectivity and the kinetics of the reaction of E-B-nitrostyrene to Z-C,N-diphenylnitrone at different temperatures and in several solvents have been studied. From the results obtained, it is evident that the reaction shows the properties of a one-step concerted process, so that it can be considered a typical [2+3]cycloaddition process.
8
Uptake of molecular oxygen by Co(II) chelates with peptides in aqueous solution. Part X. Diastereoisomeric dipeptides as auxiliary ligands in oxygen-free complexes
Kufelnicki A., Świątek M.
Polish Journal of Chemistry
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1998
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Vol. 72, nr 8
1897-1906
EN
Co(II) complexes with group of diastereoisomeric dipeptides consisting of alanine and leucine in various chiral forms have been studied in aqueous solution. The equilibria were determined by potentiometric and spectrophometric methods, using least-squares fotting procedures. The results were compared with those for glycine dipeptides containing only one asymmetric atom.
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