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    Wyświetlanie 1-9 z 9
    Tytuł:
    Kwasy nukleinowe jako katalizatory reakcji chemicznych
    Nucleic acids as catalysts in chemical reactions
    Autorzy:
    Bukowiecka-Matusiak, M.
    Sobczak, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/172466.pdf
    Data publikacji:
    2012
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    DNA
    kataliza
    synteza asymetryczna
    catalysis
    asymmetric synthesis
    Opis:
    Nucleic acids, due to their specific structure, are effective and durable carriers of genetic information. They have also been used as catalysts in chemical reactions. The right-handed DNA double helix structure has become one of the icons of modern science, and its share in asymmetric catalysis is undeniable. In these reactions, DNA is a source of chirality and proximity between oligonucleotides and complexes of copper during catalysis, what allows a direct transfer of chirality from DNA to the reaction product. Almost complete regioselectivity and excellent enantioselectivity of the aforementioned reactions in water are the evidence of the potential of asymmetry based on DNA. Asymmetric catalysis used in organic synthesis, allows achieving high enantioselectivity. This strategy has been successfully used to create new C-C bonds in Diels- Alder cycloaddition, Friedel-Crafts alkylation and Michael addition using copper complexes with oligonucleotides as catalysts. The important factor to optimize the reaction of asymmetric catalysis in the presence of DNA constitutes its sequence. It has been shown that the use of the double helix DNA can provide the product with higher enantiomeric excess than using the single strand of DNA. In addition, the results of the study suggest that Friedel-Crafts alkylation is accelerated by DNA almost 30-fold. The same correlation is observed in Diels-Alder cycloaddition. Due to promising results, further testing directed at the possibility of using catalytic DNA is being conducted.
    Źródło:
    Wiadomości Chemiczne; 2012, 66, 1-2; 119-137
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Prolina : pospolity aminokwas wyjątkowy katalizator. Część IV, Reakcja Michaela
    Proline as a common amino acid and an exceptional catalyst. Part IV, Michael reaction
    Autorzy:
    Karczmarska-Wódzka, A.
    Studzińska, R.
    Kołodziejska, R.
    Wróblewski, M.
    Dramiński, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/171840.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    prolina
    reakcja Michaela
    synteza asymetryczna
    proline
    Michael reaction
    asymmetric synthesis
    Opis:
    In recent years there has been a dynamic development of asymmetric synthesis. Groups of researchers, particularly the one led by Benjamin List and Carlos Barbas, carried out a number of reactions and showed the effectiveness of the use of small organic molecules such as proline as catalysts. Michael addition catalyzed with proline is a particularly interesting reaction because it can be carried out in two aminocatalytic pathways. The analysis of Michael reaction reveals potential for both forms of aminocatalysis: enamine and iminium catalysis (Scheme 1) [1–14]. Presumably Michael reaction proceeds mainly according to enamine mechanism. The use of proline in Michael reaction with imine activated acceptor is slightly effective. So far the researches have shown that the modification of proline molecule or addition of other catalyst is necessary for condensation to appear. Enamine catalysis concerns the activation of carbonyl compound in situ being a donor. There is no need for enolase anion to be created earlier [2, 15–17]. When, as a result of the reaction of a,b-unsaturated carbonyl compound with proline, Michael acceptor activation appears it means that it is enamine mechanism reaction (Scheme 1) [2, 24]. One of the first examples of direct Michael reaction proceeding through enamine transition state is the reaction of cyclopentanone with nitrostyrene (Scheme 6) [20–23]. Other examples of Michael addition of ketone with nitro olefin catalysed by proline are shown in table 2 and 3 [10, 23, 30]. Nitroketones obtained in that way are useful as precursors for different organic compounds [33], also pyrrolidines [34]. Pyrrolidines are pharmacologically active and they selectively block presynaptic dopamine receptors [34] (Scheme 7). Except for Michael intermolecular reaction, intramolecular condensation adducts were also obtained. Michael intramolecular proline-catalyzed condensation in which inactive ketones transform into α,β-unsaturated carbonyl compounds was described (Scheme 9) [35, 36]. These reactions require a stoichiometric amount of a catalyst and a long time of reaction and they give as a result a little enantiomeric excess [11, 24, 35]. In 1991, Yamaguchi and co-workers carried out malonates Michael addition to α, β-unsaturated aldehydes catalyzed by L-proline [24, 39]. The reaction proceeded according to enamine mechanism, for example dimethyl malonate was reacted with hex- 2-enal in the presence of proline to give Michael adduct in 44% yield. To improve the yield an attempt of a slight modification of a proline molecule was made transforming it into proper salt. Proline lithium salt enabled to obtain the condensation product in 93% yield (Tab. 4). Regardless of a used catalyst the products in the form of racemates were obtained. In order to improve enantioselective properties of a catalyst, Michael addition of diisopropyl malonate to cycloheptenone was carried out in chloroform in the presence of different proline salts. Optimal enantioselectivity and yield was obtained by using rubidium salt (Tab. 5–7) [40, 41]. Rubidium prolinate-catalyzed Michael additions are used in industry e.g. for enantioselective synthesis of the selective serotonine reuptake inhibitior (SSRI) (–)-paroxetine (antidepressant) (Scheme 12) [24].
    Źródło:
    Wiadomości Chemiczne; 2014, 68, 1-2; 49-65
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Prolina : pospolity aminokwas wyjątkowy katalizator. Część III, Reakcja Mannicha
    Proline as a common amino acid and an exceptional catalyst. Part III, Mannich reaction
    Autorzy:
    Studzińska, R.
    Karczmarska-Wódzka, A.
    Wróblewski, M.
    Kołodziejska, R.
    Dramiński, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/172649.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    prolina
    reakcja Mannicha
    synteza asymetryczna
    proline
    Mannich reaction
    asymmetric synthesis
    Opis:
    Mannich reaction occuring among ketone, aldehyde, and amine is one of the ways of a synthesis of biologically active compounds. Reactions of this type were carried out in the presence of different catalysts [3–10], however in recent years a lot of attention has been paid to enantioselective Mannich reaction catalyzed with proline. Such reactions were carried out with the use of different compounds containing carbonyl group and the most frequently used amine was p-anisidine. The advantage of the use of p-anisidine is a possibility of conducting the direct Mannich reaction (Scheme 3). In this way β-amino ketones (Tab. 1, 2, 4) [15, 18–20, 23, 24], α-hydroxy-β-amino ketones (Tab. 3) [15, 22], and β-amino alcohols (Tab. 5, 6) [25, 26] were obtained. A possibility of syntheses of β-amino sugars and α-amino acids with their derivatives (Tab. 7) [28, 29] is worth noticing. In a great number of described reactions, the products were obtained with satisfactory yield and enantiomeric excess. Taking into consideration the difficulty of a removal of p-hydroxyphenyl group which protects amine group in the resulting products, the attempts of using different amine compounds in Mannich reactions catalyzed with proline were undertaken. The use of amines blocked by tert-butoxycarbonyl group (Boc) enabled to obtain the products with high yield and ee values (Tab. 12–15) [35–38]. However in the case of the use of Boc the reaction must be carried out in an indirect way (it is necessary to prepare imine blocked by Boc earlier).
    Źródło:
    Wiadomości Chemiczne; 2014, 68, 1-2; 21-48
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Asymetryczna aminokataliza : użyteczne narzędzie w tworzeniu chemicznej różnorodności
    Asymmetric aminocatalysis : a useful tool providing access to chemical diversity
    Autorzy:
    Skrzyńska, Anna
    Przydacz, Artur
    Dyguda, Mateusz
    Topolska, Aleksandra
    Albrecht, Łukasz
    Powiązania:
    https://bibliotekanauki.pl/articles/171692.pdf
    Data publikacji:
    2020
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    synteza asymetryczna
    aminokataliza
    chiralność
    indukcja asymetrii
    związki heterocykliczne
    asymmetric synthesis
    aminocatalysis
    chirality
    asymmetric induction
    heterocyclic compounds
    Opis:
    Over the last 20 years asymmetric aminocatalysis has emerged as highly useful and reliable method of asymmetric synthesis. It involves the use of primary or secondary amines as catalysts of various stereoselective transformations of carbonyl substrates. Owing to the diverse activation strategies available in asymmetric aminocatalysis, it became a method of choice when the functionalization of prochiral aldehydes and ketones is considered. As a consequence, a direct and straightforward access to various chiral building blocks is possible that is of relevance to modern stereocontrolled organic synthesis. In the manuscript, the development of various aminocatalytic activation concepts is described and recent, selected contributions to this field of chemistry discussed. Main advantages of these strategies are highlighted providing an overview of this fascinating area of research.
    Źródło:
    Wiadomości Chemiczne; 2020, 74, 3-4; 255-284
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Trans-1,2-diaminocykloheksan – niezwykła kariera outsidera
    Trans-1,2-diaminocyclohexane – unprecedented outsider’s career
    Autorzy:
    Petryk, M.
    Kwit, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/171507.pdf
    Data publikacji:
    2013
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    struktura
    chiralność
    konformacja
    synteza asymetryczna
    rozpoznanie molekularne
    structure
    chirality
    conformation
    asymmetric synthesis
    molecular recognition
    Opis:
    An enantiopure trans-1,2-diaminocyclohexane is one of the most widely used chiral diamines in modern organic chemistry. This chiral building block, readily available from waste industrial products, emerges as a major figure in the field of asymmetric synthesis. The unique structural and conformational properties of trans-1,2-diaminocyclohexane make it very useful for the development of new synthetic strategies, taking advantage of its geometrical pre-organization. In this short article, we will highlight the utility of enantiomerically pure trans-1,2-diaminocyclohexane derivatives as broad-range chiral reagents and ligands for catalytic cycles. A brief overview of the aspects of applications in the field of molecular recognition will also be given.
    Źródło:
    Wiadomości Chemiczne; 2013, 67, 5-6; 393-442
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Practical highly enantioselective synthesis of (R)- and (S)-(E)-4-hydroxynon-2-enal
    Autorzy:
    Komisarski, Marek
    Kaczmarska, Zuzanna
    Kuśmierek, Jarosław
    Powiązania:
    https://bibliotekanauki.pl/articles/1040657.pdf
    Data publikacji:
    2009
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    asymmetric synthesis
    4-HNE enantiomers
    (E)-4-hydroxynon-2-enal (4-HNE) synthesis
    lipid peroxidation
    Candida antarctica lipase
    Opis:
    Oxidative stress enhances lipid peroxidation (LPO) implicated in cancer promotion and progression. (E)-4-Hydroxynon-2-enal 1 (trans-4-hydroxy-2-nonenal, HNE) is one of the most abundant products of LPO. Reactions of HNE with DNA and proteins are responsible for its mutagenic and toxic effects. On the other hand, HNE is regarded as a key molecule in stress mediated cell cycle signaling. LPO generates racemic HNE (rac-1); however, it is expected that the individual enantiomers will behave differently in their interactions with cell components. The study of HNE stereochemistry in its chemical and biochemical interactions is hindered by the lack of expedient methods for preparation of pure enantiomers. This study presents one step synthesis of HNE in a cross-metathesis reaction between the commercially available oct-1-en-3-ol and acrolein in the presence of 2nd generation Grubbs catalyst. The use in the metathesis reaction of enantiomers of oct-1-en-3-ol obtained via Candida antarctica lipase resolution of the racemate allowed us to prepare of 4-(R)- and 4-(S)-enantiomers of HNE (R-1 and S-1, respectively) with excellent optical purity (97.5 and 98.4% ee, respectively) and good chemical yields (70%).
    Źródło:
    Acta Biochimica Polonica; 2009, 56, 1; 189-193
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Alkaloidy kory chinowej : małe cząsteczki, które wiele mogą
    Cinchona alkaloids : small hardworkers
    Autorzy:
    Kacprzak, K.
    Czarnecki, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/172207.pdf
    Data publikacji:
    2013
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    chinina
    alkaloidy kory chinowej
    chinidyna
    synteza asymetryczna
    rozdział enancjomerów
    chiralność
    quinine
    cinchona alkaloids
    quinidine
    asymmetric synthesis
    enantiomer separation
    chirality
    Opis:
    Cinchona alkaloids comprising quinine, quinidine, cinchonidine and cinchonine as the major members constitute a unique class of quinoline alkaloids with tremendous impact on human civilization (Section 1). The odyssey of Cinchona alkaloids began with the discovery of their antimalarial properties followed by antiarrhytmic action of quinidine. Currently medicinal chemistry of Cinchona alkaloids derivatives develops rapidly and many other activities such as cytotoxic, multidrug resistance inhibitory have been demonstrated (Section 5) [5]. Beside medicine Cinchona alkaloids gave also the fundaments of stereochemistry and asymmetric synthesis. An extraordinary catalytic potency of parent and modified Cinchona alkaloids (deserving privileged catalyst classification) include more than 50 types of diverse stereoselective reactions, with few spectacular such as asymmetric dihydroxylation of alkenes or heterogeneous α-ketoesters hydrogenation (Section 3) [3]. Last but not least the portfolio of applications of Cinchona alkaloids includes resolution of racemates by diastereomeric crystallization or by the use of Cinchona- -based chiral stationary phases for ion-exchange enantioselective chromatography and other recognition or sensing systems (Section 4) [166]. Easy transformation of Cinchona alkaloids (for example by click chemistry) into other chiral and modular building blocks together with current pressure on a more intense exploration of sustainable products make cinchona alkaloids of primary importance for modern synthetic, catalytic and medicinal chemistry. The aim of this review which covers over 200 references is to briefly summarize all aspects of Cinchona alkaloid chemistry and biology with the special emphasis on new applications.
    Źródło:
    Wiadomości Chemiczne; 2013, 67, 5-6; 443-493
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Metody syntezy 2,2-bipirolidyny
    Methods for the synthesis of 2,2-bipyrrolidine
    Autorzy:
    Eichstaedt, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/172530.pdf
    Data publikacji:
    2012
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    2,2'-bipirolidyna
    aminy wicynalne
    synteza asymetryczna
    symetria C2
    2,2’-bipyrrolidine
    vicinal diamines
    asymmetric synthesis
    C2 symetry
    Opis:
    Vicinal diamine derivatives form an interesting and significant class of organic compounds. They play an essential role as chelating agents and also as ligands for asymmetric synthesis. They are used in synthesis of biologically active substances and in supramolecular chemistry [1–11]. There has been published a great number of reviews concerning the application and synthesis of 1,2-diamines with special emphasis on their organic potential [1–11]. Without any doubt, chiral 2,2’- bipyrrolidine derivatives are representative family of these compounds. They have gained particular attention since they are widely used. A remarkably broad spectrum of synthetic exploration has been reported for these agents [4, 12–14]. This paper provides description of methods for the synthesis of chiral 2,2’-bipyrrolidine. There are only seven different approaches to obtain (R,R) or (S,S)-2,2’-bipyrrolidine, five from which take advantage of stereoselective synthesis steps [15–21]. Nevertheless, a method for the synthesis of amine-1, which connects low reagents price with low time-consuming and high yield have not been described yet. Thus, creation of a new strategy for an efficient synthesis of chiral 2,2’-bipyrrolidine is still a challenging topic of studies.
    Źródło:
    Wiadomości Chemiczne; 2012, 66, 5-6; 461-483
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Chiralne amidki litu : właściwości i wybrane zastosowania syntetyczne
    Chiral lithium amides : properties and selected synthetic applications
    Autorzy:
    Piwońska, Magdalena
    Powiązania:
    https://bibliotekanauki.pl/articles/1409982.pdf
    Data publikacji:
    2021
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    chiralność
    synteza stereoselektywna
    enolan
    indukcja asymetryczna
    lit
    chirality
    stereoselective synthesis
    enolate
    asymmetric induction
    lithium
    Opis:
    Reactions involving carbonyl groups are one of the most important transformations in organic chemistry. The nucleophilic properties of carbonyl compounds, when they are in the form of enolate ions, offer many possibilities for creating new carbon-carbon bonds in reactions with electrophiles. In the case of cyclic ketones, enolate formation can be stereocontrolled by deprotonation with the use of chiral lithium amides. Stereoselective formation of the chiral lithium enolate determines the stereochemistry of the product of the subsequent reaction with the electrophile. The induction of chirality in the reaction of enolate ions with electrophiles can also be achieved by using metals other than lithium, i.e. magnesium. When other alkali metals are used, an organometallic catalyst containing a chiral ligand must be present in the reaction. The presence of particular structural elements allow distinguishing the chiral lithium amides between eight major classes. Due to the high reactivity of lithium enolates, they are often converted into the silyl enol ether. This is done in two ways: internal quench (in situ reaction with TMSCl) or external quench. Due to aggregation of the chiral lithium amides and, thus, a decrease in asymmetric induction, the addition of LiCl is necessary for reactions run in external quench conditions. Although there are known examples of the use of chiral lithium amides in a catalytic amount in the deprotonation of epoxides, there is only one example of using less than stoichiometric amounts of chiral lithium amides in the deprotonation of ketones. There are many reports in the literature on the use of chiral lithium amides in total syntheses. The chiral lithium amides were used to form chiral enol silyl ether intermediates, e.g. in synthesis of chlortetaine or (+)-ibogamine. They are also used to form chiral lithium enolates which reacts directly with electrophiles, e.g. in synthesis of lasonolide A.
    Źródło:
    Wiadomości Chemiczne; 2021, 75, 5-6; 771-798
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-9 z 9

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