scholarly journals Staudinger ligation towards cyclodextrin dimers in aqueous/organic media. Synthesis, conformations and guest-encapsulation ability

2014 ◽  
Vol 10 ◽  
pp. 774-783 ◽  
Author(s):  
Malamatenia D Manouilidou ◽  
Yannis G Lazarou ◽  
Irene M Mavridis ◽  
Konstantina Yannakopoulou
Keyword(s):  
Binding Capacity ◽  
Theoretical Calculations ◽  
Aqueous Media ◽  
Aqueous Solubility ◽  
Single Step ◽  
Organic Media ◽  
Azido Group ◽  
Staudinger Ligation ◽  
Mild Conditions ◽  
Narrow Side

β-Cyclodextrin (β-CD) dimers have been prepared using the bioorthogonal Staudinger ligation for the first time. In addition to a known linker, methyl 2-(diphenylphosphanyl)terephthalate, a doubly active linker was specifically developed that enabled connection of two β-CD units in a single step and in aqueous/organic media, under mild conditions and with good yields. A three-carbon spacer between the β-CD torus and the azido group was required for facile dimer formation. The products, as studied by NMR spectroscopy, were found to adopt closed conformations by intramolecular self-inclusion. On the other hand, association via intermolecular binding was also observed in aqueous solution, confirmed by DOSY NMR experiments. Despite self-inclusion, the β-CD cavities were capable of guest encapsulation, as shown by titration experiments: the binding constant with 1-adamantylamine was similar to that of natural β-CD. Theoretical calculations for isolated molecules (PM3 level of theory) and in the presence of solvent [water, PM3(COSMO)] as well as DFT calculations suggested that the compounds prefer to adopt conformations which bring the phenyl groups either inside the β-CD cavity (inclusion) or over its narrow side (vicinal). Thus, Staudinger ligation could be the method of choice for linking CDs exhibiting (i) ease of preparation in aqueous media, in short steps, under mild conditions and in good yields, (ii) satisfactory aqueous solubility and independent binding capacity of the cavities.

scholarly journals Σύνθεση και χαρακτηρισμός πρωτότυπων ολιγομερών κυκλοδεξτρινών για μεταφορά φαρμάκων

2014 ◽  
Author(s):  
Μαλαματένια Μανουηλίδου
Keyword(s):  
Binding Capacity ◽  
Drug Carrier ◽  
Aqueous Solubility ◽  
Single Step ◽  
Drug Formulation ◽  
Water Soluble ◽  
Amide Bond ◽  
Mild Conditions ◽  
Order Of Magnitude ◽  
High Yields

Cyclodextrins (CDs) are cyclic hollow oligosaccharide molecules that form water solublehost-guest systems, with many applications in drug formulation and delivery. CDoligomers have been previously studied due to the interest towards smart hosts withenhanced molecular recognition and binding capacity as sensors, catalysts, enzymemimics, photoreactive systems, etc. The aim of this dissertation was to prepare αCDoligomers for drug inclusion and transport with criteria: (i) ease of preparation, inaqueous media, in short steps, under mild conditions and in good yields, (ii) to obtainoligomers with satisfactory aqueous solubility and full availability of the CD cavities (iv)to achieve multiple binding with strengths better or comparable to those of parent αCD.The copper catalyzed azide-alkyne cyclization (CuAAC) reaction was utilized to preparea new water soluble cyclodextrin trimer very efficiently. The trimer engulfed threemolecules of a model guest and satisfactorily solubilized the chemotherapeutictamoxifen citrate and its active metabolite, N-desmethyltamoxifen, increasing theirsolubility by >1 order of magnitude. Moreover, for the first time the bioorthogonalStaudinger Ligation was applied to prepare αCD-dimers. For this purpose, a doublyactive linker was specifically developed that enabled dimer preparation in a single step,in aqueous/organic media, under mild conditions and with high yields. The aboveprepared products were studied in detail by NMR spectroscopy and were found toadopt, by self-inclusion, a closed conformation in aqueous solution, which completelyopened up in the presence of a suitable guest, leaving the cavities fully available to formthe corresponding inclusion complexes. Titration and DOSY NMR experimentsconfirmed the above and showed that the dimeric species form slowly diffusingaggregates in water, that in the presence of the guest partially disperse. The StaudingerLigation could thus become the method of choice for preparing CD dimers.Solubilization of practically insoluble N-desmethyl-tamoxifen was also achieved to 0.3mM. Moreover, CD dimers prepared via amide bond formation were less efficient andrequired harsh conditions. Finally, SNO-αCD derivatives were prepared andcharacterized as bimodal NO and drug carrier systems.

scholarly journals Nitrile Synthesis with Aldoxime Dehydratases: A Biocatalytic Platform with Applications in Asymmetric Synthesis, Bulk Chemicals, and Biorefineries

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4466
Author(s):  
Pablo Domínguez de María
Keyword(s):  
Asymmetric Synthesis ◽  
Organic Solvents ◽  
Raw Materials ◽  
Aqueous Media ◽  
Industrial Processes ◽  
Polymer Chemistry ◽  
Fine Chemicals ◽  
Mild Conditions ◽  
Bulk Chemicals ◽  
Recent Developments

Nitriles comprise a broad group of chemicals that are currently being industrially produced and used in fine chemicals and pharmaceuticals, as well as in bulk applications, polymer chemistry, solvents, etc. Aldoxime dehydratases catalyze the cyanide-free synthesis of nitriles starting from aldoximes under mild conditions, holding potential to become sustainable alternatives for industrial processes. Different aldoxime dehydratases accept a broad range of aldoximes with impressive high substrate loadings of up to >1 Kg L−1 and can efficiently catalyze the reaction in aqueous media as well as in non-aqueous systems, such as organic solvents and solvent-free (neat substrates). This paper provides an overview of the recent developments in this field with emphasis on strategies that may be of relevance for industry and sustainability. When possible, potential links to biorefineries and to the use of biogenic raw materials are discussed.

scholarly journals Biosensing Membrane Base on Ferulic Acid and Glucose Oxidase for an Amperometric Glucose Biosensor

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3757
Author(s):  
Gabriela Valdés-Ramírez ◽  
Laura Galicia
Keyword(s):  
Ferulic Acid ◽  
Glucose Oxidase ◽  
Aqueous Media ◽  
Glucose Biosensor ◽  
Single Step ◽  
Coefficient Of Determination ◽  
The Novel ◽  
Carbon Paste ◽  
Glucose Response ◽  
Glucose Biosensors

A biosensing membrane base on ferulic acid and glucose oxidase is synthesized onto a carbon paste electrode by electropolymerization via cyclic voltammetry in aqueous media at neutral pH at a single step. The developed biosensors exhibit a linear response from 0.082 to 34 mM glucose concentration, with a coefficient of determination R2 equal to 0.997. The biosensors display a sensitivity of 1.1 μAmM−1 cm−2, a detection limit of 0.025 mM, and 0.082 mM as glucose quantification limit. The studies reveal stable, repeatable, and reproducible biosensors response. The results indicate that the novel poly-ferulic acid membrane synthesized by electropolymerization is a promising method for glucose oxidase immobilization towards the development of glucose biosensors. The developed glucose biosensors exhibit a broader linear glucose response than other polymer-based glucose biosensors.

scholarly journals A Photochemical Strategy for Carbon Isotope Exchange with CO2

2020 ◽  
Author(s):  
Victor Babin ◽  
Alex Talbot ◽  
Alexandre Labiche ◽  
Gianluca Destro ◽  
Antonio Del Vecchio ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Isotope Exchange ◽  
Thermal Conditions ◽  
Single Step ◽  
Structural Modifications ◽  
Mild Conditions ◽  
Stark Contrast ◽  
Acetic Acids

A novel photocatalytic approach for carbon isotope exchange is reported. Utilizing [<sup>13</sup>C]CO<sub>2</sub> as primary C1 sources, this protocol allows the insertion of the desired carbon isotope into phenyl acetic acids without the need of structural modifications or pre-functionalization, in one single step. The exceptionally mild conditions required for this traceless transformation are in stark contrast with previous methods requiring the use of harsh thermal conditions.

scholarly journals Three-component synthesis of highly functionalized aziridines containing a peptide side chain and their one-step transformation into β-functionalized α-ketoamides

2016 ◽  
Vol 12 ◽  
pp. 1772-1777 ◽  
Author(s):  
Lena Huck ◽  
Juan F González ◽  
Elena de la Cuesta ◽  
J Carlos Menéndez
Keyword(s):  
Single Step ◽  
Side Chain ◽  
One Pot ◽  
Aziridine Ring ◽  
Component Process ◽  
Mild Conditions ◽  
One Step

A sequential three-component process is described, starting from 3-arylmethylene-2,5-piperazinediones and involving a one-pot sequence of reactions achieving regioselective opening of the 2,5-diketopiperazine ring and diastereoselective generation of an aziridine ring. This method allows the preparation of N-unprotected, trisubstituted aziridines bearing a peptide side chain under mild conditions. Their transformation into β-trifluoroacetamido-α-ketoamide and α,β-diketoamide frameworks was also achieved in a single step.

Strong Acid-promoted Skeletal Remodeling of the Aphid Pigment: Red Uroleuconaphin to Green Viridaphin

2022 ◽  
Author(s):  
Chiharu Ozakai ◽  
Kei Kitamura ◽  
Mitsuyo Horikawa ◽  
To-sho Hoshiyama ◽  
Akari Imamura ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Strong Acid ◽  
Single Step

We present herein a strong acid-promoted single-step transformation of red uroleuconaphin A1 into green viridaphin A2. Viridaphin A1 and bis-naphthoquinone were also obtained by performing the reaction in aqueous media....

Flavan derivatives. XVII. Epimerization of the benzylic 4-hydroxyl group in flavan-3,4-diols and the formation of 4-alkyl ethers by solvolysis

1967 ◽  
Vol 20 (10) ◽  
pp. 2151
Author(s):  
JW Clark-Lewis ◽  
LR Williams
Keyword(s):  
Aqueous Media ◽  
Cyclic Ether ◽  
Hydroxyl Group ◽  
Mechanism Of Formation ◽  
Enol Ether ◽  
Mild Conditions ◽  
Ethoxyl Group ◽  
Alkyl Ethers ◽  
By Products ◽  
Thermodynamic Factors

Epimerization and solvolysis of the benzylic 4-hydroxyl group is shown to be a general property of flavan-3,4-diols, and the diols give 4- ethoxyflavan-3-ols with ethanolic hydrochloric acid (1%). The diols are first converted into epimeric mixtures of 3,4-cis- and 3,4-trans-diols and in aqueous media cis-cis-flavan-3,4-diols yield mainly 2,3-cis-3,4- trans-diols. These 2,3-cis-3,4-diols undergo solvolysis to yield 2,3- cis-3,4-trans-4-ethoxyflavan-3-ols in which the 3,4-trans- stereochemistry is controlled by participation of the neighbouring 3ax- hydroxyl group. 2,3-trans-Flavan-3,4-diols give mixtures of trans- trans-diols and 2,3-trans-3,4-cis-diols and solvolysis first yields 2.3-trans-3,4-cis-4-ethoxyflavan-3-ols and then mixtures of the 3,4- cis- and 3,4-trans-ethers; the final proportion of these two ethers is controlled by thermodynamic factors. Solvolysis under mild conditions gives minor products considered to be 3-oxoflavans (or their enols) because of their immediate conversion into antho-cyanidins by cold acids in the presence of air, and from the formation of an enol-ether on prolonged solvolysis under more vigorous conditions. The relevance of these observations to the mechanism of formation of anthocyanidins from flavan-3,4-diols is discussed. Other by-products of solvolysis reactions include a dimeric cyclic ether (dioxan derivative) of 2,3- trans-3,4-cis-7,8,4?-trimethoxyflavan-3,4-diol. The structure and stereochemistry of solvolysis products were established by N.M.R. data; the 4-ethoxyl group in the ethers generally gave rise to an ABX3 multiplet.

Facile construction of leaf-like WO3 nanoflakes decorated on g-C3N4 towards efficient oxidation of alcohols under mild conditions

2018 ◽  
Vol 42 (20) ◽  
pp. 16523-16532 ◽  
Author(s):  
Cai Xu ◽  
Xiaozhong Wang ◽  
Gang Xu ◽  
Yingqi Chen ◽  
Liyan Dai
Keyword(s):  
Selective Oxidation ◽  
Aqueous Media ◽  
Mild Conditions ◽  
Oxidation Of Alcohols

Selective oxidation of aryl and alkyl alcohols with H2O2 in aqueous media catalyzed by a well-defined WO3/g-C3N4 composite.

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