Regioselective di- and tetra-functionalisation of γ-cyclodextrin using capping methodology

Abstract

Alkylation of γ-cyclodextrin with 3 equiv. of 1,3-bis[bis(4-tert-butylphenyl)chloromethyl]benzene, followed by permethylation afforded selectively a singly capped (A,B), as well as two doubly capped (A,B:D,E and A,B:E,F) methylated γ-CDs. Deprotection with HBF4 gave quantitatively the corresponding diols and tetrols, which constitute valuable starting compounds for further functionalisation.

Supramolecular Luminescent Sensors

“…Selective synthetic modification to access noncommercially available derivatives often begins with full protection of all the hydroxyl groups, followed by selective deprotection and further reaction at the target sites of interest . Other protecting group strategies are also available. , Using these methods, selective monofunctionalized, difunctionalized, − trifunctionalized, and tetrafunctionalized cyclodextrins , have been synthesized. Synthetic modifications to the cyclodextrin structure have the ability to dramatically change the sterics, hydrophobicity, and charge density of the cyclodextrins and have enabled the installation of covalently linked aromatic moieties .…”

Efficient synthesis of pure monotosylated beta-cyclodextrin and its dimers

“…Establishing synthetic approaches for mono-tosylation of β-cyclodextrin (βCD) was a milestone in cyclodextrin derivatization, since it allowed subsequent derivatization or coupling of βCD at its primary hydroxyl group. [1][2][3][4][5][6][7] While different methods to selectively functionalize one single primary hydroxyl group of cyclodextrins were reported, several by-products may be formed requiring extensive subsequent purification procedures. The most common synthetic strategies exploit either organic or aqueous solvent/base systems.…”

Cyclodextrin and phosphorus(iii): a versatile combination for coordination chemistry and catalysis

“…After the tritylation step and subsequent alkylation of the residual hydroxyl groups, chromatographic separation of the various alkylated species can be achieved (Scheme 14). [66][67][68][69][70] The protecting trityl groups (and their analogues) are subsequently removed under aqueous acidic conditions. This reaction pathway, dubbed the "long" method, is classical in glycochemistry and allows the synthesis of many multisubstituted CDs, including challenging γ-CD derivatives.…”

“…This reaction pathway, dubbed the "long" method, is classical in glycochemistry and allows the synthesis of many multisubstituted CDs, including challenging γ-CD derivatives. 70 In order to introduce P(III) fragments onto the CD platform, the deprotected hydroxyl groups are converted into leaving groups, usually mesyl or the more reactive triflyl groups, 71 before being reacted with nucleophiles, notably phosphides. 72 (ii) The second strategy also relies on steric hindrance but in a reverse sense.…”

“…In this respect, the length of the capping unit as well as its rigidity are crucial. [68][69][70][81][82][83][84][85] In the case of phosphine ligands, Armspach and Matt achieved this goal by bridging two CD glucose units with a single P(III) atom. The first derivatives with a phosphorus lone pair pointing towards the cavity interior (31)(32)(33)(34), were obtained by reaction of dilithium phenylphosphide (Li 2 PPh) in THF with dimesylates 27-30, respectively (Scheme 15).…”