Synthesis and transacylating reactivity of β-cyclodextrin ethylenediamines

Biomimetic Reactions Catalyzed by Cyclodextrins and Their Derivatives

“…117,124,206,207 Cyclodextrins carrying nucleophilic groups for more effective ester cleavage, albeit not with catalysis, have been widely studied. 93,193,194,200,[208][209][210][211][212][213][214][215] A quite effective true hydrolytic catalyst (19) was constructed using a nickel oximate ligand bound to a cyclodextrin carrying another metal binding group (Figure 15). 34 The oxime oxyanion is acylated, and the product then hydrolyzes to regenerate the catalyst.…”

Tight Binding of a Dimeric Derivative of Vancomycin with Dimeric l-Lys-d-Ala-d-Ala

“…Divalent interactions in molecular recognition involving two linked ligands interacting with two linked receptors have been studied in many systems, including dimers of cyclodextrin with divalent ligands, − dimers of sialyl Lewis x with E-selectin, dimers of immunophilin ligands such as FK506 and cyclosporin A with receptors active in controlling cell signal transduction, and divalent antibodies with a surface antigen. , We have begun to develop a new model systembased on polyvalent derivatives of vancomycin ( V ) and of its ligand, d -Ala- d -Ala ( d A d A )to study the physical organic chemistry and physical biochemistry of polyvalency. The binding of V with d A d A has been extensively characterized thermodynamically and structurally, − especially by Williams 15-18 and Griffin. − There is inferential evidence that spontaneous noncovalent dimerization of vancomycin and structurally related glycopeptides is responsible for their tight binding to d A d A groups in the bacterial cell wall, and thus that simultaneous interaction of the dimer with the two ligands contributes to their antibiotic action. − We now describe a system comprising synthetic dimeric derivatives of vancomycin and of d A d A that demonstrates an increase in the strength of binding of these components of approximately 10 3 relative to the analogous binding of monovalent vancomycin and d A d A .…”

Efficient synthesis of pure monotosylated beta-cyclodextrin and its dimers

“…However, the availability of pure mono-Ts-βCD at suitable quantities is required as a key substance for subsequent nucleophilic substitution, for example with ethylenediamine to obtain monoamine-βCD or bis-Et-βCD, which are of interest for instance as enzyme-like models or to create host-guest inclusion complexes. 19,20 Bis-Et-βCD is typically prepared in a two-step synthesis, in which first monoamine-βCD is formed, purified, and isolated, and subsequently reacted with mono-Ts-βCD to give the bis-Et-βCD. [19][20][21] An alternative one-step synthesis relies on DMF as an undesired solvent.…”

“…19,20 Bis-Et-βCD is typically prepared in a two-step synthesis, in which first monoamine-βCD is formed, purified, and isolated, and subsequently reacted with mono-Ts-βCD to give the bis-Et-βCD. [19][20][21] An alternative one-step synthesis relies on DMF as an undesired solvent. 22 All these methods showed low, variable yields of this reaction.…”

“…In the next step of this work, an efficient synthesis of bis-Et-βCD is introduced, which enabled high yields and avoided DMF as a solvent. While being frequently suggested as an effective complexing agent, [19][20][21] It was proposed that at least some of these issues could be overcome, if the release of p-toluenesulfonic acid from the reactant as a leaving group during the nucleophilic attack of ethylenediamine (pKb 1 =4.11 ± 0.10) to the mono-Ts-βCD may be compensated. Since p-toluenesulfonic acid will be in its anionic form in the presence of a base such as ethylenediamine, an anion exchange resin (Dowex ® 1 x 8 200-400 mesh [2 meq, exchange capacity 1.0 meq/mL] either with Cl ¯ or OH ¯ counter-ions) was directly added to the reaction mixture.…”