Ester hydrolyses catalyzed by modified cyclodextrins

Kitaura, Yoshihiko; Bender, Myron L.

doi:10.1016/0045-2068(75)90034-6

Cited by 49 publications

(15 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…consistent with the results of the analogous derivatives of CDs or other polysaccharides. 54,[56][57][58][59][60][63][64][65][66] NMR spectra of 13 C also exhibited signals characteristic to each derivative, supporting the introduction of the desired functional groups. Although the FTIR results for CM-PR300 and DEAE-PR indicated absorptions corresponding to the carboxymethyl and diethylaminoethyl groups, respectively, those for SE-PR and QA-PR did not display sufficient absorptions resulting from the introduced groups, probably because of their low DS values, as shown in the following results.…”

Section: Characterization Of the Ionic Pr Derivativesmentioning

confidence: 86%

Polyrotaxane derivatives. II. Preparation and characterization of ionic polyrotaxanes and ionic slide‐ring gels

Araki

2011

J. Polym. Sci. A Polym. Chem.

View full text Add to dashboard Cite

Four types of ionic polyrotaxane (PR) derivatives, that is, carboxymethylated, sulfoethylated, diethylaminoethylated, and trimethylammoniohydroxypropylated PRs, were successfully prepared starting from the same PR consisting of poly(ethylene glycol) as an axis and a-cyclodextrins as ring molecules. The structures of the ionic PR derivatives were analyzed by 1 H and 13 C nuclear magnetic resonance (NMR), attenuated-total reflection Fourier transform-infrared, and colloidal titration. Degrees of substitution of the ionic PRs were calculated from results of 1 H NMR and colloidal titrations; both sets of results satisfactorily agreed. Cross-linking of sulfoethylated and quaternized PRs yielded ionic slide-ring gels carrying sulfoethyl and quaternary ammonium groups on the mobile cross-links, respectively. The former gel showed intriguing phenomena, including a large degree of swelling of up to 1147, drastic change in its swelling ratio by the presence of electrolyte and bending under a moderate applied electric field (7 V/cm).

show abstract

Section: Characterization Of the Ionic Pr Derivativesmentioning

confidence: 86%

Polyrotaxane derivatives. II. Preparation and characterization of ionic polyrotaxanes and ionic slide‐ring gels

Araki

2011

J. Polym. Sci. A Polym. Chem.

View full text Add to dashboard Cite

show abstract

“…In the course of our study on the enantioselective hydrolysis (deacylation) of amino acid esters with the functional molecular assemblies composed of surfactants and reactive species, we emphasized that the stereochemical control could be attained by changing the composition of the coaggregates [1][2][3][4] and regulating ionic strength 5,6) and temperature. 7,8) Furthermore, since cyclodextrins (CyDs) have been noted as useful enzyme mimics, [9][10][11][12] we employed CyDs as host molecules and a markedly high stereoselectivity was attained in the diastereoselective deacylation of dipeptide esters. 13) On the other hand, Ueno reported the high D-enantiomer-selective deacylation of amino acid esters mediated by modified b-CyDs.…”

mentioning

confidence: 99%

Cyclodextrin-Mediated Deacylation of Amino Acid Esters with Marked Stereoselectivity.

Goto

Nakashima

Tanoue

et al. 2002

CHEMICAL & PHARMACEUTICAL BULLETIN

View full text Add to dashboard Cite

Stereoselective hydrolysis of amino acid esters have attracted considerable attention in connection with understanding the origins of the stereoselectivity observed with proteolytic enzymes. In the course of our study on the enantioselective hydrolysis (deacylation) of amino acid esters with the functional molecular assemblies composed of surfactants and reactive species, we emphasized that the stereochemical control could be attained by changing the composition of the coaggregates 1-4) and regulating ionic strength 5,6) and temperature. 7,8) Furthermore, since cyclodextrins (CyDs) have been noted as useful enzyme mimics, 9-12) we employed CyDs as host molecules and a markedly high stereoselectivity was attained in the diastereoselective deacylation of dipeptide esters.13) On the other hand, Ueno reported the high D-enantiomer-selective deacylation of amino acid esters mediated by modified b-CyDs.14) However, little has been known about the significant enantioselectivity for the deacylation of amino acid esters with unmodified CyDs. 15) In this study, we report the successful experimental results with marked enantioselectivity for the deacylation of Z-D(L)-amino acid esters (N-(benzyloxycarbonyl)-D(L)-amino acid pnitrophenyl esters) as mediated by unmodified CyDs, and the computer modeling (molecular mechanics) studies on the inclusion complexes of g-CyD with the specific substrates are also presented. Results and DiscussionWith respect to the enantioselective hydrolysis (deacyla-Leu, Phe and Trp-PNP) mediated by unmodified a-, b-and g-CyDs, the kinetic parameters obtained on the basis of the MichaelisMenten principle, the binding constant (K b ) for the formation of CyD-substrate complex and the rate constant (k 2 ) for the deacylation of substrate by CyD, are summarized in Table 1-3. The noteworthy aspects are as follows: (a) Overall, the deacylation mediated by a-CyD was favorable for all of the L-enantiomeric substrates (reflected in k 2 K b , L/Dϭ1.5-1.7), though the K b for D-isomer of Phe substrate and k 2 values for D-isomer of Ala substrate were larger than those for the corresponding L-isomers. (b) In the case of the reaction by bCyD, L-enantiomer-selectivity was also observed for the deacylation of Ala, Leu and Phe substrates (L/Dϭ1.5-3.2), while D-enantiomeric selectivity (D/Lϭ1.4) was observed for the deacylation of Trp substrate. (c) Relatively higher L-enantioselectivity was obtained in the deacylation mediated by gCyD (L/Dϭ2.6-9.0). Most remarkably, the highest enantioselectivity (L/Dϭ9.0) was attained for the deacylation of Ala substrate. Furthermore, it was also attractive that this fairly high enantioselectivity (L/Dϭ9.0) could be mainly originated in the deacylation process of substrates, because it was reflected by a fairly large k 2 L /k 2 D value (7.4) and a smallOn the other hand, Table 4 shows the results of energies for the inclusion complexes on Z-D(L)-Ala-PNP having different shapes with g-CyD calculated by molecular mechanics with water solvent effects. It was suggested that the con...

show abstract

“…PNPA hydrolysis reaction is an ideal model reaction for its simple mechanism, widely investigated to obtain information on the catalytic and selectivity properties of CDs [7,8,9]; an improved reaction rate and productivity has been already observed when the reaction was carried out in the catalyzed ~-CD carbonate membrane reactor in comparison to the alkaline batch reactor [1]. Figure 1 and table 3 show the reaction rate, productivity and conversion degree obtained for the five membrane reactors.…”

Section: Resultsmentioning

confidence: 96%

Preparation and Characterization of PEEK-WC/β-Cyclodextrin Carbonate Membranes

Pagliero

Natoli

Trotta

et al. 1996

Proceedings of the Eighth International Symposium on Cyclodextrins

View full text Add to dashboard Cite

Membranes of PEEKlWC containing carbonate derivative ~-cyclodextrin (~-CD) have been prepared and their catalytic behaviour for the p-nitrophenylacetate (PNPA) hydrolysis has been investigated. The effect of different average degree of ~-CD carbonate substitution (DS), the amount of immobilized ~-CD carbonate and operating stirring speeds have been examined under a constant substrate concentration and constant permeation rate. The performance and productivity of the ~-CD membrane reactor indicate an improvement of CD stability. 20n leave from:

show abstract

Ester hydrolyses catalyzed by modified cyclodextrins

Cited by 49 publications

References 15 publications

Polyrotaxane derivatives. II. Preparation and characterization of ionic polyrotaxanes and ionic slide‐ring gels

Polyrotaxane derivatives. II. Preparation and characterization of ionic polyrotaxanes and ionic slide‐ring gels

Cyclodextrin-Mediated Deacylation of Amino Acid Esters with Marked Stereoselectivity.

Preparation and Characterization of PEEK-WC/β-Cyclodextrin Carbonate Membranes

Contact Info

Product

Resources

About