Synthesis of Mono(perfluoroalkyl) Cyclodextrins via Cross Metathesis

Synthesis of trans-Tetrafluoro(trifluoromethyl)-λ6-sulfanyl (CF3SF4)-Containing Olefins via Cross Metathesis

The cross-metathesis reactions of trans-tetrafluoro(trifluoromethyl)-λ⁶-sulfanyl (CF₃SF₄)-containing olefins expand the repertoire of synthetic transformations of CF₃SF₄-substituted molecules. Treatment of a primary alkene and 3-CF₃SF₄-propene with a second-generation Hoveyda-Grubbs catalyst yielded the cross-metathesis product in good yield under very mild conditions (room temperature). CF₃SF₄-propene undergoes cross metathesis with substrates containing electron-withdrawing groups or electron-donating groups at room temperature or under dichloromethane reflux. The formation of the CF₃SF₄-propene homodimer and the utility of that dimer to undergo selective cross-metathesis reactions are described.

Host-guest interactions for extracting antibiotics with a γ-cyclodextrin poly(glycidyl-co-ethylene dimethacrylate) hybrid sorbent

A procedure for the solid-phase extraction of antibiotics (enoxacin, ofloxacin, norfloxacin, ciprofloxacin, and sparfloxacin) in water has been developed. The sorbent used is based on a poly(glycidyl-co-ethylene dimethacrylate) network, whose previously modified surface has been functionalized with γ-cyclodextrin through a click-chemistry reaction. The architecture of the material has been characterized by thermogravimetric analysis, N₂ adsorption-desorption, Raman spectroscopy, confocal microscopy, and scanning electron microscopy, showing good capability to be used as a filler for extraction cartridges. The optimization of the extraction methodology shows good intra-day and inter-day repeatability of the extraction procedure, with coefficients of variation between 2.5 and 5.1% and the possibility of reusing the material at least five times. The detection limits of the method have been established at the μg L^-1 level, confirming the possibility of quantifying trace levels. To end, real groundwater samples have been analyzed and the results are comparable with those obtained with a reference method. The proposed material can be used for assessing the presence of antibiotics in aqueous environments through an extraction procedure taking advantage of the presence of γ-cyclodextrin on its structure.

Mono-6-Substituted Cyclodextrins-Synthesis and Applications

Cyclodextrins are well known supramolecular hosts used in a wide range of applications. Monosubstitution of native cyclodextrins in the position C-6 of a glucose unit represents the simplest method how to achieve covalent binding of a well-defined host unit into the more complicated systems. These derivatives are relatively easy to prepare; that is why the number of publications describing their preparations exceeds 1400, and the reported synthetic methods are often very similar. Nevertheless, it might be very demanding to decide which of the published methods is the best one for the intended purpose. In the review, we aim to present only the most useful and well-described methods for preparing different types of mono-6-substituted derivatives. We also discuss the common problems encountered during their syntheses and suggest their optimal solutions.

Negatively charged cyclodextrins: Synthesis and applications in chiral analysis-A review

The negatively charged cyclodextrins (CDs) play an important role in chiral analysis due to the additional electrostatic effect beyond the host-guest inclusion, especially in enantioanalysis of positively charged and electrically neutral analytes. This review presents recent advances in application of anionic CDs for enantioanalysis during the past five years. Firstly, the synthesis approaches of random substitution and single isomers of anionic CDs are briefly discussed. The main part focuses on the chiral analysis using anionic CDs in various analytical techniques, including capillary electrophoresis, high-performance liquid chromatography, capillary electrochromatography, counter current chromatography, nuclear magnetic resonance, etc. Particular attention is given to the capillary electrophoresis application since charged CDs could be used as a carrier of enantiomers by virtue of their self-mobility and offer an easy adjustment of the enantiomer migration order. Finally, future opportunities are also discussed in the conclusion of this review.

Synthesis and supramolecular properties of regioisomers of mononaphthylallyl derivatives of γ-cyclodextrin

Monosubstituted derivatives of γ-cyclodextrin (γ-CD) are suitable building blocks for supramolecular polymers, and can also serve as precursors for the synthesis of other regioselectively monosubstituted γ-CD derivatives. We prepared a set of monosubstituted 2^I-O-, 3^I-O-, and 6^I-O-(3-(naphthalen-2-yl)prop-2-en-1-yl) derivatives of γ-CD using two different methods. A key step of the first synthetic procedure is a cross-metathesis between previously described regioisomers of mono-O-allyl derivatives of γ-CD and 2-vinylnaphthalene which gives yields of about 16-25% (2-5% starting from γ-CD). To increase the overall yields, we have developed another method, based on a direct alkylation of γ-CD with 3-(naphthalen-2-yl)allyl chloride as the alkylating reagent. Highly regioselective reaction conditions, which differ for each regioisomer in a used base, gave the monosubstituted isomers in yields between 12-19%. Supramolecular properties of these derivatives were studied by DLS, ITC, NMR, and Cryo-TEM.

Cross-metathesis reaction of α- and β-vinyl C-glycosides with alkenes

Cross-metathesis of α- and β-vinyl C-deoxyribosides and α-vinyl C-galactoside with various terminal alkenes under different conditions was studied. The cross-metathesis of the former proceeded with good yields of the corresponding products in ClCH2CH2Cl the latter required the presence of CuI in CH2Cl2 to achieve good yields of the products. A simple method for the preparation of α- and β-vinyl C-deoxyribosides was also developed. In addition, feasibility of deprotection and further transformations were briefly explored.

Synthesis of 3I-O and 2I-O-monosubstituted derivatives of per-6-azido-β-cyclodextrin-potential molecular scaffolds

Alkylation of per-6-azido-β-cyclodextrin by a suitable electrophilic reagent (cinnamyl bromide or propargyl bromide) gave a mixture of 3(I)-O and 2(I)-O regioisomers. After peracetylation and chromatographic separation on silica gel, pure isomers were isolated. Oxidative cleavage of cinnamyl double bond afforded the corresponding formylmethyl and carboxymethyl derivatives. The prepared scaffold molecules are equipped with two types of reactive groups which have a potential to serve as points of attachment for various compounds.

Cross-metathesis of allylcarboranes with O-allylcyclodextrins

Cross-metathesis between allylcarboranes and O-allylcyclodextrins was catalyzed by Hoveyda-Grubbs 2(nd) generation catalyst in toluene. The corresponding carboranyl-cyclodextrin conjugates were isolated in 15-25% yields.