Wyniki wyszukiwania - Biblioteka Nauki

1

Badania nad syntezą węglanu propylenu

100%

Klimiec J. , Fabisz E.

Przemysł Chemiczny

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2000

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tom T. 79, nr 10

339-340

PL

Przedstawiono wyniki badań nad syntezą węglanu propylenu z tlenku propylenu i ditlenku węgla w obecności różnych układów katalitycznych (chlorek wapnia + trietyloamina lub chlorek alkilowy + trietyloamina) rozpuszczonych w węglanie propylenu. Proces prowadzono metodą ciągłą w instalacji laboratoryjnej pod ciśnieniem 10 MPa, w temp. ok. 210°C, przy obciążeniu reaktora tlenkiem propylenu wynoszącym ok. 0,40 kg/dm3 o h. Największą wydajność węglanu propylenu (powyżej 95%), przy stopniu przereagowania tlenku propylenu wynoszącym powyżej 99%, uzyskano w obecności katalizatora składającego się z chloroparafiny i trietyloaminy.

2

Otrzymywanie i właściwości wybranych kwasów 2-(2-acylofenoksy)alkanowych oraz ich zastosowanie w syntezie nowych benzofuranów i 1,4-benzoksazepin

88%

Kwiecień H.

Prace Naukowe Politechniki Szczecińskiej. Instytut Technologii Chemicznej Organicznej

|

2001

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tom Nr 548(3)

5-140

3

Komputerowe projektowanie wieloetapowych syntez organicznych : stan aktualny i kierunki rozwoju

75%

Nowak G. , Fic G.

Przemysł Chemiczny

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2011

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tom T. 90, nr 1

78-83

4

Nowoczesne metody pozyskiwania substancji biologicznie aktywnych przy zastosowaniu reakcji wieloskładnikowych ze szczególnym uwzględnieniem reakcji Ugi

75%

Ryng S. , Jęśkowiak I.

Wiadomości Chemiczne

|

2017

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tom [Z] 71, 1-2

45--63

EN

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].

5

Synteza nowych 2-arylo-3-fenylo-4-nitro-tetrahydro-1,2-oksazoli w 1,3-dialkiloimidazoliowej cieczy jonowej

75%

Dresler E. , Jasiński R.

|

2015

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tom T. 94, nr 12

2244-2246

PL

1,3-Dipolarne cykloaddycje nitroetenu do (Z)-C-fenylo-N-arylonitronów w chlorku 1-butylo-3-metyloimidazoliowym realizują się w temperaturze pokojowej i prowadzą do mieszanin stereoizomerycznych 3,4-cis i 3,4-trans-2-arylo-3-fenylo-4-nitrotetrahydro-1,2-oksazoli z wydajnościami na poziomie 80–85%. Struktury zsyntezowanych oksazoli zostały potwierdzone danymi analizy elementarnej oraz spektroskopii 1H NMR i IR.

EN

1,3-Dipolar cycloaddn. of CH2=CHNO2 to 3-Me, 4-Br, 3-Br and 4-NO2-substituted (Z)-C-phenyl-N-arylnitrones in 1-butyl-3-methylimidazolium chloride at room temperature gave mixts. of 3,4-cis and 3,4-trans-2-aryl-3-phenyl-4-nitrotetrahydro-1,2-oxazoles in yields 80–85%. The structure of the oxazoles was confirmed by elementary anal. as well as 1HNMR and IR spectroscopies.

6

Click chemistry - czyżby rewolucja w syntezie organicznej?

75%

Kacprzak K.

Wiadomości Chemiczne

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2005

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tom [Z] 59, 7-8

583--611

EN

In 2001 prof. K.B. Sharpless from Scripps Institute has announced a new idea for an easier and faster molecular discovery, named click chemistry. This concept bases on the following observations: -currently organic chemists invest too much effort in assembling the structure, although it is the function that is sought. The function can be also found in molecules that are more easy to synthesise. -nature prefers carbon-heteroatom bond formation and most biomolecules are formed from small building blocks containig and connected by such bonds. Thus, the focus should be given to the efficient carbon-heteroatom bond formation. -estimated pool of potential drug-like molecules (<500 Da, <30 non-hydrogen atoms, only C, H, O, N, S, P, F, Cl, Br, stable at room temperature, in the presence of water and air) is between 1062-1063. This is the space for exploration. Click chemistry embraces therefore a set of powerful! reactions which must be modular, wide in scope, highly yielding, generating easily removable byproducts (with no need for chromatographic purification) and stereoselective. These reaction should be also insensitive to oxygen and water and preferably carried out under simple conditions. Click reactions achieve their efficienty due to the high thermody-namic driving force, usually greater than > 20 kcal/mol (thus can be recognized as spring-loaded for a single trajectory). Examples of these reactions include: nucleo-philic opening of strained rings (epoxides, aziridines), cycloadditions (e.g. 1,3-di-polar or Diels-Alder type reaction), additions to carbon-carbon multiple bond (epo-xidation, dihydroxylation, Michael addition) and some types of carbonyl chemistry . An illustration of this concept is multigram 4-step synthesis of products 2a and 2b (Scheme 2) without the use of chromatography. Click chemistry idea was discussed in detail by Sharpless in [1] and [4]. Huisgen 1,3-dipolar cycloadditon is cream of the crop of various click reactions and was used in many notable applications of click chemistry concept, high-ligh-ted in this review. This reaction is strongly thermodynamically activated (35-50 kcal/mol), modular and of wide scope, it shows also perfect atom economy and provides products with high yield after usually simple workup. Moreover, due to the stability of reactants and 1,2,3-triazoles to various reactions conditions, including oxygen and water, this cycloaddition can be carried out in water. Target guide synthesis combined with 1,3-dipolar Huisgen reaction was used for finding new, most potent (active in femtomolar concentration) acetylcholine este-rase inhibitors and carbonic anhydrase inhibitors 5a,b. Other inhibitors developed by synthesis and screening of 1,2,3-triazole libraries include a-l,3-fukosyltransferase VI, HlV-prote-ase. 1,3-Dipolar cycloaddition was also used for modification of antibiotic tyrosidine and vancomycine and the modified products 10a,b and 11a,b exhibit better therapeutic index and activity respectively. Important applications of Huisgen reaction in molecular biology include bioconiugation and labeling techniques. Cowpea virus was efficiently labeled by fluorescein derivatives and cell surfaces were decorated by various biotin derivatives using appropriate azide-alkyne components. Click chemistry in this field was also used for designing new methods for labeling protein, in vitro or in vivo protein profiling (Scheme 11) [27] and DNA sequencing. Many important applications of 1,3-Huisgen cycloaddition are found in material chemistry. These include efficient synthesis of dendrimers wihout the use of chromatography ordendronised polymers. 1,2,3-Triazole linker formation was utilised for functionalisation of poly(norbornenes), modular copolymer synthesis and silicon waffers or gold surface modification. 1,3-Dipolar cycloaddition was also used in the synthesis of new fluorescent cumarines 54, two-photon absorption chromophores 55 and water-soluble calixarenes 56. Huisgen reaction was recently widely explored for modification of natural products and biomolecules and many interesting 1,2,3-triazole derivatives of sugars, aminoacids and peptides, lipids, steroids and alkaloids were synthesised (62-74). In summary, in a relatively short period of time after its introduction, click chemistry concept was widely approved in various areas and resulted in many important applications. Thus it can be regared as a versatile toolbox for "production of molecular properties".

7

Preparation of conjugated nitroalkenes: short review

75%

Zawadzińska K. , Gaurav G. K. , Jasiński R.

Scientiae Radices

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2022

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tom Vol. 1, Iss. 1

69--83

EN

Key protocols of the preparation of conjugated nitroalkenes were reviewed and critically discussed. It was established, that optimal strategy for the obtaining of target compounds are small molecules extrusion processes from saturated nitro-compounds. Among them, the most universal methodologies based on carboxylic acids elimination have been discussed, which provide for smooth applications.

8

Niskotemperaturowe ciecze jonowe : ciekawostka laboratoryjna czy zapowiedź rewolucji technologicznej? Cz. 2 Zastosowanie cieczy jonowych w syntezie organicznej i w ekstrakcji

75%

Kosmulski M. , Marczewska-Boczkowska K. , Saneluta C.

Przemysł Chemiczny

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2002

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tom T. 81, nr 2

106-110

9

Synteza nowych związków zapachowych z 2-metylofuranu. Cz. II. Synteza nowych cyklicznych acetali

75%

Nowicki J. , Gora J.

Pollena. Tłuszcze. Środki Piorące. Kosmetyki

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1998

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tom 42

|

nr 11

455-457

10

Nowa technologia wytwarzania calcipotriolu - aktywnej substancji farmaceutycznej leku przeciw łuszczycy

75%

Przemysł Chemiczny

|

2006

|

tom T. 85, nr 4

223-223

11

Kompleks mocznikowo-wodoronadtlenkowy jako efektywny i ekologiczny czynnik utleniający w syntezie organicznej

75%

Podraza A. , Pielichowski J.

Przemysł Chemiczny

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2013

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tom T. 92, nr 2

158-164

12

Zastosowanie polimerów jako katalizatorów w reakcjach katalizy międzyfazowej

75%

Bogdał D. , Pielichowski J.

Czasopismo Techniczne. Chemia

|

1998

|

tom R. 95, z. 3-Ch

1--25

EN

A survey of molecules capable of working as phase-transfer catalysts (PTC) is presented. The mechanism of reactions carried out under phase-transfer catalytic conditions and factors that govern such reactions are described. The classical catalysts (e. g., the description of structural factors of their activity. Next the polymer systems that can be used as catalysts under PTC conditions were presented.

13

Desililujące sprzęganie winylosilanów i etynylosilanów w sekwencjach reakcji w syntezie organicznej

63%

Prukała W.

|

tom [Z] 62, 9-10

779-826

EN

An efficient formation of carbon-carbon bonds belongs to one of the most important transformations in synthetic chemistry. The reaction is predominantly catalyzed by the late transition metals [1, 2]. Traditional methods that have been employed, to accomplish this transformation include Stille and Suzuki reactions. However, due to a number of drawbacks inherent to the substrates used in these reactions, organosilicon reagents have emerged as competitive alternatives (the facility of preparation and purification of silanes, their high stability, and low-molecular weight). Because of the low polarizability of the C-Si bond, the silicon function must undergo nucleophilic activation to induce migration of a transferable group onto the organopalladium species (transmetallation) [3-8]. The family of palladium-based catalysts, used in the desilylative coupling reaction (DC), tolerates the presence of the majority of functional groups. The paper gives a review of literature focused on the application of desilylative coupling in sequential reactions published till the end of 2007. The activity of different catalytic systems based on palladium compounds in desilylative coupling reactions has been characterized. The influence of some substituents and activators on the reaction as well as their mechanisms has been presented [36, 41, 94-104]. It is remarkable, that the two entirely different mechanisms can be operative for both fluoride and fluoride-free silanolate couplings [104-110], and that both are highly efficient room temperature reactions. Alkenylsilanes, used in sequential reactions, can be efficiently prepared by several stereo- and regioselective methodologies involving classical stoichiometric routes from organometallic reagents and, more recently, transition-metal-catalyzed transformations of alkynes and silylalkynes (via the hydrosilylation, Sonogashira reaction), alkenes (the dehydrogenative silylation [10, 12, 13], cross-metathesis [9-11], Heck reaction), and other silicon derivatives. Moreover, the paper provides a characterization of the desilylative coupling reaction (DC) conditions. Several independent sequential reactions (one-pot, tandem reaction), e.g. RCM/DC, Stille/DC, Heck/DC, Sonogashira/DC, cross-metathesis/DC, silylative coupling/DC etc., and their applications to the synthesis of biologically active compounds have been presented. The paper is completed with a list of the most important, in the author's opinion, monographs and review works on the application of the desilylative coupling catalysed by palladium compounds in organic synthesis.

14

Biokatalityczne metody otrzymywania nieracemicznych alkoholi aryloallilowych

63%

Szymkuć S. , Ostaszewski R.

Wiadomości Chemiczne

|

2012

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tom [Z] 66, 1-2

93-118

EN

Different methods for preparing nonracemic arylallylic alcohols are presented in this work. A key feature was an application the biocatalyst as a mean to obtain final products. These compounds play an important role in pharmaceutical industry, because they are substrates in the synthesis of various important therapeutics [1–3]. Methods presented in this work are divided into five main groups: 1. enantioselective hydroxylation, 2. microbiological deracemization, 3. enzymatic kinetic resolution, 4. enzymatic dynamic kinetic resolution, 5. enantioselective reduction. First two methods use only microorganisms like bacteria [4, 5, 10], fungi [6–8] or yeasts [11] as biocatalysts. Owing to the metabolic processes in the cells it was possible to obtain nonracemic arylallylic alcohol (results for method 2 are presented in Table 1). Unfortunately, the data were insufficient to create direct correlation between values of enantiomeric excess and types of applied microorganisms. Methods 3 and 4 used only isolated enzymes as biocatalysts. They belong to two classes: hydrolases and oxidoreductases. Oxidoreductases were used in the enzymatic kinetic resolution based on the enantioselective oxidation [28] of one enantiomer of the racemic arylallylic alcohol. Nevertheless, hydrolases [12–27], mainly lipases, isolated from microorganisms are enzymes of common use in enzymatic kinetic resolution. Owing to this method it was possible to obtain final products with excellent enantioselectivity (results are presented in Tables 2 and 3). Because kinetic resolution and dynamic kinetic resolution are related processes, in most cases similar enzymes are used. The choice of lipases as biocatalysts for method 4 was caused by the fact that they are able to catalyze enantioselective transesterification of arylallylic alcohols or their acetates. Furthermore, racemization is very important factor for efficacy of dynamic kinetic resolution processes. In most cases they are catalyzed by different types of complexes based on palladium [30, 31] and ruthenium [32, 34]. Final products prepared by this method had very high enantiomeric excesses and yields up to 93% (results are presented in Tables 4 and 5). The only method, presented in this work, that allowed to use both enzymes [39–41] and microorganisms [35–38] as biocatalysts, was enantioselective reduction. This method allows to obtain nonracemic arylallylic alcohols with excellent enantiomeric excess and yields up to 85% (results are presented in Table 6). In summary, all methods presented in this work show the advantages of biocatalysis as an alternative route to traditional chemical method

15

Otrzymywanie i zastosowanie alkoholu 2-metyloallilowego w przemysłowej syntezie organicznej

63%

Żółtański A. , Siwak T.

Przemysł Chemiczny

|

2019

|

tom T. 98, nr 9

1479--1484

PL

Alkohol metyloallilowy, po wdrożeniu w skali technicznej ekonomicznych metod jego otrzymywania, stał się dostępnym surowcem dla przemysłowej syntezy organicznej. Przedstawiono przegląd aktualnej literatury dotyczącej metod produkcji tego związku i kierunków jego dalszych zastosowań, gdzie dominująca pod względem skali jest synteza polikarboksylanowych superplastyfikatorów dla mieszanek betonowych.

EN

A review, with 71 refs., of phys.-chem. properties, synthesis methods and applications mainly as polycarboxylate superplasticizers for concrete as well as an in prodn. of drugs, pesticides and fragrances.

16

Ciecze jonowe w metatezie olefin : wyzwania i bariery

63%

Barteczko N. , Grymel M. , Chrobok A.

Przemysł Chemiczny

|

2020

|

tom T. 99, nr 6

927--933

PL

Metateza olefin stanowi jedno z najskuteczniejszych narzędzi syntezy organicznej w ostatnich latach. Ciecze jonowe (IL) ze względu na ciekawe właściwości, takie jak mała prężność par, możliwość projektowania oraz duża zdolność rozpuszczania szerokiej gamy związków organicznych, nieorganicznych i metaloorganicznych, stosowane są w reakcjach metatezy jako alternatywne rozpuszczalniki wobec różnych układów katalitycznych. Przedstawiono przykłady zastosowania IL w metatezie olefin, a także związane z tym wyzwania i bariery.

EN

A review, with 71 refs., of ionic liqs. used in olefin metathesis as alternative solvents.

17

Kwasowe ciecze jonowe jako katalizatory w przemysłowej syntezie organicznej

63%

Matuszek K. , Chrobok A.

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2016

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tom T. 95, nr 6

1215--1220

PL

Dokonano przeglądu literatury dotyczącej zastosowania kwasowych cieczy jonowych jako katalizatorów w syntezie organicznej. Ciecze te mogą posiadać centrum kwasowości Lewisa lub Brønsteda ulokowane w strukturze kationu i/lub anionu. Opisano metody wyznaczania kwasowości cieczy jonowych, przedstawiono ich charakterystykę oraz przykłady zastosowania jako katalizatorów w typowych reakcjach katalizowanych za pomocą kwasów (alkilowanie Friedla i Craftsa, reakcja Dielsa i Aldera oraz estryfikacja).

EN

A review, with 58 refs., of Lewis and Brønsted acidic ionic liqs. as catalyst in Friedel-Crafts alkylation, Diels-Alder reaction and esterification.

18

Biotransformacje z udziałem drożdży

63%

Białecka-Florjańczyk E. , Krzyczkowska J. , Stolarzewicz I.

Przemysł Chemiczny

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2011

|

tom T. 90, nr 5

691-695

19

Anion alkoksyallenowy w syntezie związków naturalnych i ich analogów

63%

Busiak B. , Utecht G. , Jasiński M.

Wiadomości Chemiczne

|

2016

|

tom [Z] 70, 1-2

3--23

EN

Among diverse systems containing multiple bonds, cumulenes are recognized as the most reactive derivatives towards both nucleophilic and electrophilic agents, and for this reason, they are considered as important class of substrates for organic synthesis. Over the last three decades alkoxyallenes have been demonstrated as highly useful C3-building blocks for the construction of numerous N-, O-, and S-containing heterocycles, including enantiomerically pure compounds. Special attention has been paid to lithiated alkoxyallenes as suitable nucleophiles for the reactions with alkyl halides, strained heterocycles, carbonyl compounds and their derivatives. The presence of the allene unit in the initially formed adducts opens up several possibilities in the preparation of more complex systems. In this review, selected applications of lithiated alkoxyallenes in the synthesis of natural products and their analogues are discussed.

20

Wykorzystanie promieniowania mikrofalowego w syntezie organicznej

63%

Markowski J. , Oleksik J.

Przemysł Chemiczny

|

2014

|

tom T. 93, nr 6

934-937

PL

Przedstawiono przegląd wybranych zastosowań promieniowania mikrofalowego w syntezie organicznej.

EN

A review, with 51 refs., of chem. reactions carried out in microwave field.