New chiral selectors: Design and synthesis of 6‐TBDMS‐2,3‐methyl β‐cyclodextrin 2‐2′ thioureido dimer and 6‐TBDMS‐2,3‐methyl (or 2‐methyl‐3‐acetyl) β‐cyclodextrin bearing an (<i>R</i>) mosher acid moiety

Cravotto, Giancarlo; Bicchi, Carlo; Tagliapietra, Silvia; Costa, Luisa; Carlo, Stefano Di; Nervi, Carlo

doi:10.1002/chir.20069

Cited by 12 publications

(7 citation statements)

References 40 publications

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“…The synthesis of various per-2,3- O -alkyl-6-TBDMS-βCDs was carried out in DMF, using US [ 112 , 113 ]. These fluidizable derivatives are suitable for coating glass surfaces and showed excellent chiral gas-chromatographic separation properties.…”

Section: Discussionmentioning

confidence: 99%

Toward a Greener World—Cyclodextrin Derivatization by Mechanochemistry

Jicsinszky

Cravotto

2021

Molecules

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Cyclodextrin (CD) derivatives are a challenge, mainly due to solubility problems. In many cases, the synthesis of CD derivatives requires high-boiling solvents, whereas the product isolation from the aqueous methods often requires energy-intensive processes. Complex formation faces similar challenges in that it involves interacting materials with conflicting properties. However, many authors also refer to the formation of non-covalent bonds, such as the formation of inclusion complexes or metal–organic networks, as reactions or synthesis, which makes it difficult to classify the technical papers. In many cases, the solubility of both the starting material and the product in the same solvent differs significantly. The sweetest point of mechanochemistry is the reduced demand or complete elimination of solvents from the synthesis. The lack of solvents can make syntheses more economical and greener. The limited molecular movements in solid-state allow the preparation of CD derivatives, which are difficult to produce under solvent reaction conditions. A mechanochemical reaction generally has a higher reagent utilization rate. When the reaction yields a good guest co-product, solvent-free conditions can be slower than in solution conditions. Regioselective syntheses of per-6-amino and alkylthio-CD derivatives or insoluble cyclodextrin polymers and nanosponges are good examples of what a greener technology can offer through solvent-free reaction conditions. In the case of thiolated CD derivatives, the absence of solvents results in significant suppression of the thiol group oxidation, too. The insoluble polymer synthesis is also more efficient when using the same molar ratio of the reagents as the solution reaction. Solid reactants not only reduce the chance of hydrolysis of multifunctional reactants or side reactions, but the spatial proximity of macrocycles also reduces the length of the spacing formed by the crosslinker. The structure of insoluble polymers of the mechanochemical reactions generally is more compact, with fewer and shorter hydrophilic arms than the products of the solution reactions.

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Section: Discussionmentioning

confidence: 99%

Toward a Greener World—Cyclodextrin Derivatization by Mechanochemistry

Jicsinszky

Cravotto

2021

Molecules

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“…The development of new CD derivatives as important selectors for analytical chiral recognition have been performed [ 27 ]. We prepared heptakis(6-O-TBDMS-2,3-O-methyl)-β-CDs with a second CD unit in the 2 position or a ( R )-Mosher acid moiety [ 28 ].…”

Section: Reviewmentioning

confidence: 99%

Enabling technologies and green processes in cyclodextrin chemistry

Cravotto¹,

Caporaso²,

Jicsinszky³

et al. 2016

Beilstein J. Org. Chem.

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SummaryThe design of efficient synthetic green strategies for the selective modification of cyclodextrins (CDs) is still a challenging task. Outstanding results have been achieved in recent years by means of so-called enabling technologies, such as microwaves, ultrasound and ball mills, that have become irreplaceable tools in the synthesis of CD derivatives. Several examples of sonochemical selective modification of native α-, β- and γ-CDs have been reported including heterogeneous phase Pd- and Cu-catalysed hydrogenations and couplings. Microwave irradiation has emerged as the technique of choice for the production of highly substituted CD derivatives, CD grafted materials and polymers. Mechanochemical methods have successfully furnished greener, solvent-free syntheses and efficient complexation, while flow microreactors may well improve the repeatability and optimization of critical synthetic protocols.

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“…[14,15] In addition to the cooperative binding through which the two adjacent CD cavities of these bridged bis(CD)s can encapsulate guest molecules, the linker can contribute to the stabilization of such complexes by providing additional binding interactions or contributing to extending the overall binding site. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] Secondary-face-linked β-CD dimers often show higher complexing constants than those bridged by primary faces, [18][19][20][21]35] probably due to the fact that guest Scheme 1. CD units can be linked through their primary faces, i.e., 6-6Ј bis(CD), through a head-to-tail fashion, i.e., 6-2Ј or 6-3Ј bis(CD), and through their secondary faces, i.e., 2-2Ј or 3-3Ј bis(CD).…”

Section: Introductionmentioning

confidence: 99%

Secondary Face‐to‐Face 2–2′ β‐Cyclodextrin Dimers Linked with Fluorescent Rigid Spacer Arms: A Cyclodextrin‐Based Ratiometric Sensor for Bile Salts

et al. 2012

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The synthesis of a series of β‐cyclodextrin (CD) dimers in which the two macrocycle units are linked by rigid‐rod phenylene‐ethynylene tethers of different length and shape through the cyclodextrin secondary sides is reported. The synthesis involves Sonogashira coupling reactions for construction of the tethers and final grafting of the CD units by click chemistry. The self‐aggregation of the synthesized CD dimers in aqueous medium was investigated by fluorescence spectroscopy, isothermal titration calorimetry and dynamic light scattering. Rigid‐rod‐tethered cyclodextrin dimers formed polydisperse nanoparticles of 240 to 480 nm in water solution depending on the tether shape, and exhibited fluorescence. The binding and fluorescence sensing abilities of the CD dimers toward sodium cholate and deoxycholate were studied. As a result, the newly synthesized rigid‐rod‐tethered cyclodextrin dimers proved to be very sensitive fluorescent chemosensors. A new cyclodextrin‐based ratiometric fluorescence probe has thus been developed for the detection of bile salts such as sodium cholate and deoxycholate.

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New chiral selectors: Design and synthesis of 6‐TBDMS‐2,3‐methyl β‐cyclodextrin 2‐2′ thioureido dimer and 6‐TBDMS‐2,3‐methyl (or 2‐methyl‐3‐acetyl) β‐cyclodextrin bearing an (R) mosher acid moiety

Cited by 12 publications

References 40 publications

Toward a Greener World—Cyclodextrin Derivatization by Mechanochemistry

Toward a Greener World—Cyclodextrin Derivatization by Mechanochemistry

Enabling technologies and green processes in cyclodextrin chemistry

Secondary Face‐to‐Face 2–2′ β‐Cyclodextrin Dimers Linked with Fluorescent Rigid Spacer Arms: A Cyclodextrin‐Based Ratiometric Sensor for Bile Salts

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