- Acetylation of α- And β-cyclodextrines
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Applying acetyl chloride and versatile bases and solvents per- and regioacetylated derivatives of α- and β-cyclodextrines were prepared. Conditions were established for performing regiodirected acetylation of the primary hydroxy groups of α- and β-cyclodextrines in the presence of free secondary hydroxy groups.
- Grachev,Edunov,Kurochkina,Popkov,Levina,Nifant'Ev
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- Complexes of peracetylated cyclodextrin in a non-aqueous aprotic medium: the role of residual water
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This paper describes the interaction between aromatic esters and peracetylated cyclodextrins (CDs) studied by NMR spectroscopy in deuterochloroform (CDCl3). The observed chemical shift changes highlight the existence of interactions between an aromatic alkyl ester, water and peracetylated CDs. In some cases, substituent chemical shift determination was influenced by the low water content of CDCl3 and/or the host molecule. Higher CD concentrations resulted in water signal drifts in all studied cases. It was not possible to obtain a completely dry sample of peracetyl γCD: ~1 mol of water remained and the water signal showed reversed movement, with respect to the other two CD analogues, upon increasing host concentration. The estimated 1 : 1 stability constants for the water : peracetyl CD complexes are in the 50-150 M-1 range in CDCl3, but show a relatively large calculation error. The calculated 1 : 1 stability constants for the peracetyl CD : ester complexes are also in this range, but 1 : 2 and 2 : 1 complex compositions are also possible. Overall, our results highlight dynamic aspects of water nanoconfined in a highly hydrophobic environment, thus mimicking biological recognition where a few water molecules often play a pivotal role.
- Jicsinszky, Laszlo,Martina, Katia,Caporaso, Marina,Cintas, Pedro,Zanichelli, Andrea,Cravotto, Giancarlo
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- A simple and convenient per-O-acylation of cyclodextrins catalyzed by molecular iodine
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Per-O-acylated cyclodextrins with different alkyl chains were prepared in good to high yields by iodine-catalyzed acylation of all hydroxy groups of cyclodextrins with carboxylic anhydrides under solvent-free conditions. Georg Thieme Verlag Stuttgart - New York.
- Ide, Yasuhiro,Hori, Yuji,Kobayashi, Soichi,Hossain, Md. Delwar,Kitamura, Tsugio
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- Effective Synthesis and Modification of α-Cyclodextrin-Based [3]Rotaxanes Enabling Versatile Molecular Design
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One-pot synthesis of various α-cyclodextrin-(α-CD-) based [3]rotaxanes in water and their structural modifications are discussed in detail. Pseudo[3]rotaxane was prepared from α-CD and α,ω-diaminododecane in water (above 100 g, quantitative yield in a 1 L
- Akae, Yosuke,Sogawa, Hiromitsu,Takata, Toshikazu
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supporting information
p. 3605 - 3613
(2019/06/17)
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- Structural Analysis and Inclusion Mechanism of Native and Permethylated α-Cyclodextrin-Based Rotaxanes Containing Alkylene Axles
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Native α-cyclodextrin- (α-CD) and permethylated α-CD (PMeCD)-based rotaxanes with various short alkylene chains as axles can be synthesized through a urea end-capping method. Native α-CD tends to form [3]- or [5]pseudorotaxanes and not [2]- or [4]pseudorotaxanes, which indicates that the coupled CDs act as a single fragment. End-capping reactions of the pseudorotaxanes with C18 and C24 axle lengths do not occur because the axle termini are covered by the densely stacked CDs. The number of PMeCDs on the pseudorotaxane is flexible and mainly depends on the axle length. Peracetylated α-CD (PAcCD)-based rotaxanes are synthesized through O-acetylation of the α-CD-based rotaxanes without any decomposition of the rotaxanated structures. The structures of PMeCD-based [3]- and [4]rotaxanes, and the molecular dynamics calculations on [3]pseudorotaxanes, indicate that the tail face of PMeCDs is regularly directed toward the axle termini. On the basis of the results obtained, it can be concluded that the directions and numbers of CDs in rotaxanes containing short alkylene chains depend on 1)the interactions between CDs, 2)the length of the alkylene axle, and 3)the interactions between the axle end and tail face of the CD. Come on in! Native and permethylated α-cyclodextrin (CD)-based rotaxanes with various short alkylene axles are synthesized with a urea end-capping method. The directions and number of the CD wheels depend on the interactions between CDs, the axle length, and the interactions between axle ends and the tail face of the CDs (see figure).
- Akae, Yosuke,Koyama, Yasuhito,Sogawa, Hiromitsu,Hayashi, Yoshihiro,Kawauchi, Susumu,Kuwata, Shigeki,Takata, Toshikazu
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supporting information
p. 5335 - 5341
(2016/04/09)
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- Oligosaccharide analogues of polysaccharides part 22: Synthesis of cyclodextrin analogues containing a buta-1,3-diyne-1,4-diyl or a butane-1,4-diyl unit
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The peracetylated hexaamylose (maltohexaose) 18 was obtained by an improved acetolysis of cyclomaltohexaose (α-cyclodextrin, α-CD, 16), and transformed into the benzyl- and 4-chlorobenzyl-protected thioglycosides 22 and 23, respectively (Scheme 2). Sequen
- Hoffmann, Barbara,Zanini, Diana,Ripoche, Isabelle,Buerli, Roland,Vasella, Andrea
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p. 1862 - 1888
(2007/10/03)
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