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Tytuł:
Metody syntezy pochodnych organicznych zawierających wiązanie potrójne węgiel-węgiel
Methods for the synthesis of organic derivatives containing the triple bond carbon-carbon
Autorzy:
Bylińska, I.
Guzow, K.
Powiązania:
https://bibliotekanauki.pl/articles/171636.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
wiązanie potrójne
acetylen
synteza
homosprzęganie
heterosprzęganie
reakcja Glasera
reakcja Haya
reakcja Cadiota-Chodkiewicza
reakcja Sonogashiry-Hagihary
triple bond
acetylene
synthesis
homocoupling
heterocoupling
Glaser reaction
Hay reaction
Cadiot-Chodkiewicz reaction
Sonogashira-Hagihara reaction
Opis:
Compounds containing triple bonds are lately in the centre of interest of many research groups. This is mainly connected with their usefulness as substrates to obtain complex compounds with various applications in different areas of science, industry and medicine [1–5]. Because of that many researchers are interested in methods of synthesis of such compounds. As the demand for derivatives with triple bonds is quite big and the one universal method of synthesis does not exist, the new ones are developed or these already known are improved. To enable choosing the best method for synthesis of acetylene derivatives, this review is presented. The oldest methods based on elimination reaction are mentioned [6–9], whereas those enabling incorporation of acetylene unit into more complicated compounds are described more thoroughly [10–92]. The latter methods based on homo- or heterocoupling lead to symmetrical [10–25] and unsymmetrical acetylene and bisacetylene derivatives [26–92]. The most popular reactions such as Glaser reaction (Scheme 1) [10–12], Cadiot-Chodkiewicz reaction (Schemes 11 and 12) [26–49], Hay reaction (Scheme 13) [13, 14] as well as Sonogashira-Hagihara reaction [50–69] and their modifications (Tab. 3) [57] are described. Moreover, the influence of main parameters such as type of substrate used, ratio of reagents, catalyst, base, solvent, reaction time and temperature on the reaction yield is presented (Tabs 1–4) [14, 18, 23, 25, 50–58, 69–78].
Źródło:
Wiadomości Chemiczne; 2012, 66, 9-10; 935-961
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nowoczesne metody pozyskiwania substancji biologicznie aktywnych przy zastosowaniu reakcji wieloskładnikowych ze szczególnym uwzględnieniem reakcji Ugi
New methods of receive biologically active substances in multicomponent reactions with particular focus on Ugi reaction
Autorzy:
Ryng, S.
Jęśkowiak, I.
Powiązania:
https://bibliotekanauki.pl/articles/172211.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
reakcja wieloskładnikowa
reakcja Ugi
synteza organiczna
synteza ukierunkowana na różnorodność
multicomponent reaction
Ugi reaction
diversity-oriented synthesis
Opis:
In the last decade a change of thought has taken place in the pharmaceutical industry which has led to a renaissance of the Multicomponent reactions (MCRs) [1]. Under the inspiration of diversity-oriented-synthesis (DOS), numerous efforts have been devoted to find powerful synthetic tools for rapidly accessing maximum molecular diversity with minimum cost. In the toolbox enabling DOS for generating molecular libraries, MCRs are now recognized as one of the most useful and powerful strategies [2], which provide the highest number of compounds for the least synthetic effort [3]. Following the rapid progress in the research area of MCRs, widespread application has been found in many different areas such as chemical biology, natural product synthesis, pharmaceuticals as well as agrochemistry [2]. The overall aim of a DOS is to generate a small-molecule collection with a high degree of structural, and thus functional, diversity that interrogates large areas of chemical space simultaneously [4]. In Targed-Oriented Synthesis (TOS) a complex target is transformed into a sequence of progressively simpler structures by formally performing chemical reactions in the reverse-synthetic direction [3]. Special subclasses are isocyanide based MCRs (IMCRs). They are particularly interesting because they are more versatile and diverse than the remaining MCRs. Today most MCRs chemistry performed with isocyanides relates to the classical reactions of Passerini and Ugi (Scheme 1)[5]. In Ugi four-component reaction (U-4CR), carboxylic acids, primary amines and oxo components (aldehydes or ketones) react with isocyanides in polar solvents to obtain -amino carboxamides (Schemes 2 and 3). Occasionally however, selective conversion of amide groups into other functional groups is desirable for an increase of diversity of the IMCR-derived compounds [6]. In this reaction two substituted amide groups are formed under release of one equivalent of water. Thus, the U-4CR is an atom-economic and environmentally friendly reaction. It was also shown that water can be used as the solvent. This reaction is typically performed by stirrling the components for approximately 1 day in small quantities of a protic solvent (e.g. methanol or trifluoroethanol) [7]. The examples of Ugi reactions are described in the Schemes 4–10. Multicomponent reactions have become attractive tools in modern synthetic organic chemistry. Among their many advantages, they allow the creation of large chemical libraries of diverse, complex molecular structures, starting from simple materials within a short time frame. Not surprisingly, these particular features have made MCRs especially appealing to medicinal chemists [8].
Źródło:
Wiadomości Chemiczne; 2017, 71, 1-2; 45-63
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prolina – pospolity aminokwas wyjątkowy katalizator. Część I, Biosynteza proliny. Wewnątrzcząsteczkowa kondensacja aldolowa
Proline as a common amino acid and an exceptional catalyst. Part I, Proline biosynthesis. Intramolecular aldol reaction
Autorzy:
Wróblewski, M.
Kołodziejska, R.
Studzińska, R.
Karczmarska-Wódzka, A.
Dramiński, M.
Powiązania:
https://bibliotekanauki.pl/articles/172473.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
biosynteza proliny
mechanizm kondensacji aldolowej
wewnątrzcząsteczkowa reakcja aldolowa
proline biosynthesis
mechanism of aldol reaction
intramolecular aldol reaction
Opis:
In asymmetric synthesis of organic compounds more effective solutions are being looked for which will result in higher yield(s) of product(s) and their high enantioselectivity [1]. One of such solutions is an use of a multilevel and cheap catalyst. Proline used as a catalyst is a substance of natural origin which was synthetically obtained by Willstätter who was carrying out research on hygric acid (Scheme 1) [10]. The cells of many organisms have a suitable enzymatic system essential for proline biosynthesis [15]. So far, three proline biosynthesis pathways have been described: from glutamate (Scheme 3 and 4), ornithine (Scheme 5 and 6), and arginine (Scheme 7) [16–28]. Proline which is obtained as a result of biosynthesis or supplementation is a substrate for many proteins. Characteristic and significant content (about 23%) of this amino acid was observed in collage. In cells proline can play an important role of osmoregulator [31–35] – a protective substance regulating the activity of such enzymes as catalase and peroxidase [36]. Proline as a secondary amine shows exceptional nucleophilicity facilitating imine and enamine formation. Used as a catalyst in aldol reaction makes with substrates like imine or enamine transition state imitating the activity of naturally occurring enzymes for this type of reaction, that is aldolases. In their research Hajos and Parrish, and Eder, Sauer and Wiechert used proline in intramolecular aldol reaction obtaining proper enones (Scheme 9) [60–62]. The process of intramolecular aldol reaction was used for a separation of racemic mixture of diketones (Scheme 10) [63, 64], cyclization of ortho-substituted aromatic aldehydes and ketones (Scheme 11) [65], synthesis of cyclic diketones (Scheme 13) [68] and domino reaction to obtain substituted cyclohexanones from beta-diketones and unsaturated ketones (Scheme 14) [69].
Źródło:
Wiadomości Chemiczne; 2013, 67, 9-10; 801-818
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enancjoselektywna enzymatyczna desymetryzacja katalizowana oksydoreduktazami. Reakcje utleniania. Część 1
Enantioselective enzymatic desymmetrization catalyzed by oxidoreductases. Oxidation reactions. Part 1
Autorzy:
Karczmarska-Wódzka, A.
Kołodziejska, R.
Tafelska-Kaczmarek, A.
Studzińska, R.
Wróblewski, M.
Augustyńska, B.
Powiązania:
https://bibliotekanauki.pl/articles/172799.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
dehydrogenaza
monooksygenaza
reakcja utleniania
dehydrogenase
monooxygenase
oxidation reaction
Opis:
The main advantage of biotransformation involving enzymes, compared to chemical processes, is a highly selective formation of products with precise configuration. Herein we describe enzymes participating in the oxidation processes, especially dehydrogenases and monooxygenases. Dehydrogenases are not only able to catalyze the enantioselective reduction of prochiral ketones, but they can also desymmetrize meso and prochiral diols through the enantioselective oxidation. As a result of this processes, optically active hydroxyketones, hydroxycarboxylic acids, and their derivatives are obtained. Cytochrome P450 monooxygenases (CYPs) constitute a family of heme-containing enzymes which exhibits a variety of catalytic activities. They catalyze different reactions, such as hydroxylation, epoxidation, oxidative deamination, or N- and (S)-oxidation. In the oxidation reaction with monooxygenases, the whole cells are commonly used as catalysts. The use of monooxygenases in the oxidation reaction of prochiral alkanes provides the optically active alcohols. It is very significant that these transformations are still difficult to carry out by chemical methods. Baeyer-Villiger monooxygenases (BVMO EC 1.14.13.X) effectively catalyze the nucleophilic and electrophilic oxidation reactions of various functional groups. BVMO are highly regio- and stereoselective enzymes, and their catalytic potential is used in the synthesis of optically pure lactones and esters. Keywords:
Źródło:
Wiadomości Chemiczne; 2015, 69, 1-2; 35-51
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:
Enancjoselektywna enzymatyczna desymetryzacja katalizowana oksydoreduktazami. Reakcje utleniania. Część 2
Enantioselective enzymatic desymmetrization catalyzed by oxidoreductases. Oxidation reactions. Part 2
Autorzy:
Karczmarska-Wódzka, A.
Kołodziejska, R.
Tafelska-Kaczmarek, A.
Studzińska, R.
Wróblewski, M.
Augustyńska, B.
Powiązania:
https://bibliotekanauki.pl/articles/172457.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
dioksygenaza
oksydaza
peroksydaza
reakcja utleniania
dioxygenase
oxidase
peroxidase
oxidation reaction
Opis:
In continuation of our work, we herein describe next enzyme classes applied for oxidation reaction. Dioxygenases, oxidases, and peroxidases are successfully used in the synthesis of desymmetrization products with high yields and enantiomeric excesses. Aromatic dioxygenases, such as toluene dioxygenase (TDO), naphthalene dioxygenase (NDO), and biphenyl dioxygenase (BPDO) found in the prokaryotic microorganisms are enzymes belonging to the dioxygenase class and are the most commonly used in organic synthesis. The α-oxidation of various fatty acids in the presence of an α-oxidase from germinating peas is one of the few examples of oxidases application in asymmetric organic synthesis. The intermediary α-hydroxyperoxyacids can undergo two competing reactions: decarboxylation of the corresponding aldehydes or reduction to the (R)-2-hydroxy acids. In order to eliminate the competitive decarboxylation reaction tin(II) chloride is used as an in situ reducing agent. Peroxidases are the redox enzymes found in various sources such as animals, plants, and microorganisms. Due to the fact that, in contrast to monooxygenases, no additional cofactors are required, peroxidases are highly attractive for the preparative biotransformation. Oxidation reactions catalyzed by (halo)peroxydases are also often used in organic synthesis. N-Oxidation of amines, for instance, leads to the formation of the corresponding aliphatic N-oxides, aromatic nitro-, or nitrosocompounds. From a preparative synthesis standpoint, however, sulfoxidation of thioether is important since it was proven to proceed in a highly stereo- and enantioselective manner. Furthermore, depending on the source of haloperoxidase, chiral sulfoxides of opposite configurations can be obtained.
Źródło:
Wiadomości Chemiczne; 2015, 69, 1-2; 53-64
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:
Reakcje utleniania wybranych grup funkcyjnych z wykorzystaniem oxone® jako źródła tlenu cząsteczkowego
The oxidation reactions of selected functional groups using oxone® as a source of molecular oxygen
Autorzy:
Zawadzki, P.
Czardybon, W.
Chrobok, A.
Powiązania:
https://bibliotekanauki.pl/articles/172053.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
oxone
ciecze jonowe
reakcja utleniania
epoksyd
ionic liquids
oxidation reaction
epoxide
Opis:
Oxidation reactions belong to the group of the most commonly used processes in both organic and inorganic chemistry. The main issues in such transformation are usually safe handling of the oxidants as well as waste generation. Peroxymonosulfuric acid is one of the strongest oxidants. It was described for the first time in 1898 by Heinrich Caro. Nowadays, the commercial sources of KHSO5 are low-cost industrial bulk chemicals, e.g., the triple salt Oxone® (2KHSO5· KHSO4·K2SO4). These products are stable oxidizing agents commonly used in fine chemicals synthesis, and are easy to handle, non-toxic as well as generate non-polluting by-products. Over the past several years the scope of its use has extended. One of the most important transformation that have been made possible with the use of Oxone® are epoxidation and ketone formation. Epoxides and ketones are important synthetic building blocks widely used in the chemical industry for the production of pharmaceutical products, flavours, fragrances, resins, adhesives and paints. The use of Oxone® was demonstrated in several combinations both in classical methods that involved metal catalysis as well as in novel approaches with the use of microwaves and ionic liquids. Over the past 20 years, ionic liquids, together with supercritical fluids and water, have become powerful alternatives to conventional organic solvents. Ionic liquids are salts having in the structure an organic cation and an inorganic or organic anion, with a melting point below 100°C. The advantage of using ionic liquids is a big variety of available structures. Combinations of both ionic liquids and Oxone® offer an interesting alternative to classical oxidation methods used in industry.
Źródło:
Wiadomości Chemiczne; 2016, 70, 5-6; 289-297
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Syntetyczne odpowiedniki fosfoenolopirogronianu, czyli jak naśladować biosyntezę kwasów ulozonowych
Synthetic equivalents of phosphoenolpyruvate : how to imitate the biosynthesis of ulosonic acids
Autorzy:
Molenda, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/172729.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
reakcja aldolowa
równoważnik pirogronianu
kwasy ulozonowe
aldol reaction
pyruvate unit
ulosonic acids
Opis:
Ulosonic acids are key intermediated in many important biochemical pathways. One of them is DAH, which takes part in the shikimic acid pathway, as precursor in aromatic amino acids biosynthesis [1]. Another interesting compound is KDN isolated from rainbow trout egg [2], where it is responsible for the protection of the embryo in the early stages of embryonic development [3]. In the nature ulosonic acids are synthesized from phosphorylated sugar aldehydes and phosphoenolpyruvate in enzymatic aldol reaction. Mimic of enzymatic catalysis by asymmetric direct aldol reaction is one of the challenges of modern organic synthesis. Unfortunately, installation of the pyruvate unit in laboratory conditions is quite problematic. The aim of this short review was to present synthetic equivalents of phosphoenolpyruvate, which over the years become more and more similar to the biosynthesis of ulosonic acids in living cells. The first applied pyruvic acid unit was 2-acethylthiazole used as stoichiometric lithium enolate in aldol addition [9]. Next, the same research group used the phosphine derivative of 2-acethylthiazole in Wittig olefination of sugar aldehydes with subsequent stereoselective syn Michael addition of the benzyl oxide anion. Another puryvate equivalent is dimethyl acetal of pyruvic aldehyde successfully used in organocatalytic [12] and metalorganocatalytic [14] direct aldol reactions. Nowadays sterically hindered aromatic ester of pyruvic acid is probably the best puryvate unit. This ester was successfully used as aldol reaction donor in synthesis of two 3-deoxy-2-ulosonic acids – KDG and KDO [18]. Aryl pyruvate reacts with aldehydes to give aldol product with high efficiency and good diastereoselectivity in reaction catalyzed by chiral tertiary amines represented by Cinchona alkaloids. Chiral sugar aldehydes and pyruvate ester, are the building blocks that famously mimic the biological precursors of ulosonic acids.
Źródło:
Wiadomości Chemiczne; 2014, 68, 9-10; 873-896
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reakcja Mitsunobu : mechanizm i zastosowanie
Mitsunobu reaction : mechanism and application
Autorzy:
Kitkowska, J. D.
Tabaczyńska, Ż. A.
Dramiński, M.
Powiązania:
https://bibliotekanauki.pl/articles/171670.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
reakcja Mitsunobu
kondensacja
inwersja konfiguracji
stereoselektywność
Mitsunobu reaction
condensation
configuration inversion
stereoselectivity
Opis:
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.
Źródło:
Wiadomości Chemiczne; 2013, 67, 9-10; 843-876
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Przełączniki molekularne : rodzaje i zastosowania
The molecular switches : types and applications
Autorzy:
Bartyzel, K.
Powiązania:
https://bibliotekanauki.pl/articles/171660.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
przełączniki molekularne
ditienyloeteny
materiały molekularne
reakcja elektrocyklizacji
molecular switches
dithienylethenes
molecular materials
electrocyclization reaction
Opis:
A subject of this work is group of organic compounds known as molecular switches. Molecular switches are described as chemical compounds which molecules have at least two thermodynamically stable states. Conversion between these states is reversible and may be induced by such factors as change of the temperature or flow of the electric current or irradiation of the molecule with the light of particular wavelength [1]. Especially interesting are photochromic molecular switches. In this group the conversion is triggered by irradiation with a light of a particular wavelength [2]. Because of its unique properties, this type of compounds is extensively studied by the scientists, who investigate their photochromic properties as ways of using them in coordination with lanthanide metals and construction of novel molecular materials [3]. Especially interesting group of photochromic molecular switches is class named diarylethenes. This type of compounds after irradiation with UV light undergo cyclization, which is reversible under light of the visible spectrum (Figure 1). The other important group of photochromic molecular switches is class of compounds possessing in their structure chiroptic unit. The irradiation of the molecule with left- and right-handed circularly polarized light leads to change of the absolute configuration (Fig. 8) [1]. This type of switches may be used in construction of synthetic molecular motors which is widely studied subject nowadays [1]. The other groups of molecular switches are host- guest molecular switches and mechanically- interlocked molecular switches. In the first mentioned before group the bistable states differ in their affinity for guests (Fig. 15) [14]. The second one is based on the group of compounds named catenanes and rotaxanes. They can be described as two chemical individuals, mechanically interlocked in each other, which are not connected with chemical bonds (Fig. 19). This kind of molecular switches are used in construction of the logic gates [1].
Źródło:
Wiadomości Chemiczne; 2015, 69, 7-8; 561-584
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Katalizatory palladowe immobilizowane w materiałach typu MOF aktywne w reakcjach uwodornienia
Palladium catalysts immobilized in MOF materials active in hydrogenation reactions
Autorzy:
Augustyniak, Adam W.
Trzeciak, Anna M.
Powiązania:
https://bibliotekanauki.pl/articles/172135.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
sieci metaliczno-organiczne
kataliza
pallad
uwodornienie
selektywność
metal-organic frameworks
catalysis
palladium
hydrogenation
reaction
selectivity
Opis:
Palladium immobilized in metal-organic frameworks (MOF) exhibit promising catalytic properties in hydrogenation of different unsaturated substrates. Due to the specific porous and crystalline structure MOFs can contribute in bonding and activation of organic substrates, increasing catalytic efficiency of Pd@MOF composites. The superior tunability of MOFs structures enables to design highly selective catalysts for hydrogenation of different substrates, such as olefins, esters, ketones, alcohols or alkynes. Due to the synergistic effects of palladium and MOF not only high activity but also high selectivity can be achieved. The article presents representative examples of MOF-based palladium catalysts for hydrogenation to illustrate perspectives, also technological, of their application.
Źródło:
Wiadomości Chemiczne; 2019, 73, 3-4; 221-241
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prolina – pospolity aminokwas wyjątkowy katalizator. Część II, Międzycząsteczkowa kondensacja aldolowa
Proline as a common amino acid and an exceptional catalyst. Part II, Intermolecular aldol reaction
Autorzy:
Kołodziejska, R.
Wróblewski, M.
Karczmarska-Wódzka, A.
Studzińska, R.
Dramiński, M.
Powiązania:
https://bibliotekanauki.pl/articles/171560.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
międzycząsteczkowa reakcja aldolowa donor
akceptor
prolina
anti-aldole
intermolecular aldol reaction
donor
acceptor
proline
anti-aldol
Opis:
Proline in organic synthesis is used as a small molecular organocatalyst. In a catalytic act proline, similarly to an enzyme, activates reagents, stabilizes transition state and influences an orientation of substrates [1–12]. Proline works as aldolase I (so called microaldolase I). In comparison with other amino acids it shows exceptional nucleophilicity which makes imines and enamines formation easier. In the intermolecular aldol reaction proline was used for the first time by List and co-workers (Scheme 1) [3, 9, 20]. Since then an immense progress has been observed in this field. Several aldolization reactions were performed in the presence of proline. Reactions of this type proceed between the donor (nucleophile) and the acceptor (electrophile). In aldol reaction the donors can be both ketones and aldehydes which next are condensed with ketones and aldehydes acting as electrophiles (Scheme 2–18; Tab. 1–7) [21–72]. The presence of proline ensures not only high yield of homo- and heteroaldolization but mainly enables conducting enantio- and diastereoselective synthesis. Intermolecular proline-catalyzed aldol condensation proceeds according to enamine mechanism. Anti-aldols, which make a valuable source of intermediates in the synthesis of important biologically active compounds, are mainly obtained in this reaction [35–44, 54, 58, 62, 63, 68, 69, 71].
Źródło:
Wiadomości Chemiczne; 2013, 67, 11-12; 1027-1050
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modele eksperymentalne w badaniach zewnątrzkomórkowego transportu miedzi
Experimental models in studies of extracellular copper transport
Autorzy:
Bal, Wojciech
Powiązania:
https://bibliotekanauki.pl/articles/2200581.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
copper(II)
peptide
complexation
reaction kinetics
biological mechanisms
miedź(II)
peptyd
kompleksowanie
kinetyka reakcji
mechanizmy biologiczne
Opis:
The biological relevance of proteins and peptides for Cu(II) biology, including the extracellular transport of this element, is commonly estimated by studying stabilities and structures of their complexes. However, our experimental studies on the kinetics of formation of Cu(II) complexes of ATCUN/NTS and Xaa-His-R peptides, considered to be key actors in extracellular copper biology, revealed novel long-lived reaction intermediates. These intermediates, rather than the final reaction products fulfil the chemical criteria for actual biocomplexes derived from biological studies. Our research clearly demonstrated that understanding of the kinetic aspect of interactions is indispensable for realistic modeling of biological interactions of metal ions.
Źródło:
Wiadomości Chemiczne; 2022, 76, 5-6; 456-466
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reakcje asymetrycznego otwierania pierścienia azyrydyn
Asymmetric aziridine ring opening reactions
Autorzy:
Prusinowska, N.
Powiązania:
https://bibliotekanauki.pl/articles/171513.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
azyrydyny
desymetryzacja
kataliza asymetryczna
rozdział kinetyczny
reakcje otwierania pierścienia
aziridines
desymmetrization
asymmetric catalysis
kinetic resolution
ring opening reaction
Opis:
Aziridines, the nitrogenous analogues of epoxides, are useful building blocks for the synthesis of various functional materials and biologically active compounds. The reactivity of aziridines toward ring opening and expansion is dependent upon their extremely strained ring structures. Among the procedures of ring opening of aziridines, a nucleophilic ring-opening reaction is one of the major routes to highly functionalized compounds (Scheme 2). This short review focused on essentiac asymmetric ring opening reactions of aziridines including enantioselective ring opening of meso-aziridines and kinetic resolution of racemic aziridines with various hetero and carbon nucleophiles towards the synthesis of highly enantiomerically enriched 1,2-difunctionalized fine chemicals.
Źródło:
Wiadomości Chemiczne; 2013, 67, 5-6; 585-618
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
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