Heptakis- 3-cyclodextrin

U Holzgrabe, H Mallwitz, SK Branch, TM Jefferies, M Wiese. Chiral discrimination by NMR spectroscopy of ephedrine and JV-methylephedrine induced by /3-cyclodextrin, heptakis(2,3-di-0-acetyl)-/3-cyclodextrin and hep-takis-(6-0-acetyl)-/3-cyclodextrin. Chirality 9 211-219, 1997. 

This method was proposed by P. Husek (ref. 5) and involves the analysis of the lactic acid in the form of dioxolanone using GC on a chiral stationary phase comprising a derivative of the p-cyclodextrine heptakis (2,3,6 tri O methyl) p-cyclodextrine. The derivatization reaction is as follows ... 

The second method used GC on a CSP comprising a derivative of (3-cyclodextrine (heptakis (30 acetyl, 2-6 di O pentyl) (3-cyclodextrine). 

Heptakis(6-methoxyethylamine-6-deoxy)-p-cyclodextrin 2-Hydroxypropyltrimethylammonium-P-cyclodextrin Mono-(6-delta-glutamylamino-6-deoxy)-P-cyclodextrin Heptakis(2-Al,Al-dimethylcarbamoyl)-P-cyclodextrin 7... 

Glass capillary column (38 m X 0.2 mm i.d.) coated with heptakis (3-0-acetyl-2,6-di-0-pentyl)-/3-cyclodextrin... 

Recently, multidimensional GC has been employed in enantioselective analysis by placing a chiral stationary phase such as a cyclodextrin in the second column. Typically, switching valves are used to heart-cut the appropriate portion of the separation from a non-chiral column into a chiral column. Heil et al. used a dual column system consisting of a non-chiral pre-column (30 m X 0.25 mm X 0.38 p.m, PS-268) and a chiral (30 m X 0.32 mm X 0.64 p.m, heptakis(2,3-di-(9-methyl-6-(9-tert-butyldimethylsilyl)-(3-cyclodextrin) (TBDM-CD) analytical column to separate derivatized urinary organic acids that are indicative of metabolic diseases such as short bowel syndrome, phenylketonuria, tyrosinaemia, and others. They used a FID following the pre-column and an ion trap mass-selective detector following the... 

The same authors studied the CL of 4,4,-[oxalylbis(trifluoromethylsulfo-nyl)imino]to[4-methylmorphilinium trifluoromethane sulfonate] (METQ) with hydrogen peroxide and a fluorophor in the presence of a, p, y, and heptakis 2,6-di-O-methyl P-cyclodextrin [66], The fluorophors studied were rhodamine B (RH B), 8-aniline-l-naphthalene sulfonic acid (ANS), potassium 2-p-toluidinylnaph-thalene-6-sulfonate (TNS), and fluorescein. It was found that TNS, ANS, and fluorescein show CL intensity enhancement in all cyclodextrins, while the CL of rhodamine B is enhanced in a- and y-cyclodextrin and reduced in P-cyclodextrin medium. The enhancement factors were found in the range of 1.4 for rhodamine B in a-cyclodextrin and 300 for TNS in heptakis 2,6-di-O-methyl P-cyclodextrin. The authors conclude that this enhancement could be attributed to increases in reaction rate, excitation efficiency, and fluorescence efficiency of the emitting species. Inclusion of a reaction intermediate and fluorophore in the cyclodextrin cavity is proposed as one possible mechanism for the observed enhancement. 

Recently, it was found that the commercially available heptakis(2,3,6-tri-0-methyl)-/i-cyclodextrin (permethylated /1-cyclodextrin, TRIMEB), induced nonequivalence in the NMR spectra, in CD3OD, of enantiomeric mixtures of trisubstituted allenes devoid of polar functional groups, thus affording a simple and general way to determinations of their enantiomeric purity63. 

Barretta and coworkers63 reported a direct determination of the enantiomeric purity of chiral trisubstituted allenes by using permethylated cyclodextrin as a chiral solvating agent. They found that the heptakis ft-cyclodextrin TRIMEB discussed above can be successfully used as a chiral solvating agent (CSA) for the NMR determination of the enantiomeric purity of trisubstituted allenes llOa-f. An accurate analysis of the experimental conditions (molar ratio aliene/TRIMEB, temperature and solvent) required to optimize the enantioseparation has been carried out. The XH NMR spectra of TRIMEB, allenes llOa-f, and the mixtures TRIMEB/allene have been recorded at 300 MHz in CD3OD as solvent. 

Ropivacaine hydrochloride is a long-acting local anesthetic, which is manufactured as the pure S-enantiomer. The enantiomeric purity is determined by CZE, using heptakis-(2,6-di-0-methyl)-j5-cyclodextrin as chiral selector. A resolution of 3.7 between the two enantiomers is required for the system suitability solution. The percentage R-enantiomer is calculated relative to the S-enantiomer in the same electropherogram, and should not exceed 0.5%. In Eigure 5, a representative electropherogram is presented. 

Marini, R. D., Servais, A.-C., Rozet, E., Chiap, P., Boulanger, B., Rudaz, S., Crommen, J., Hubert, P., and Fillet, M. (2006). Nonaqueous capillary electrophoresis method for the enantiomeric purity determination of 5-timolol using heptakis(2,3-di-0-methyl-6-0-sulfo)-p-cyclodextrin validation using the accuracy profile strategy and estimation of uncertainty. /. Chromatogr. A 1120(1—2), 102-111. 

The inclusion modes of flurbiprofen with beta cyclodextrin and with heptakis(2,3,6-tri-0-methyl)-beta cyclodextrin have been studied by Imai and coworkers. They showed that, although the Cotton effects in the circular dichroic spectra induced by beta cyclodextrin in / (-) and 5(+) flurbiprofen are identical, those induced by heptakis(2,3,6-tri-0-methyl)-beta cyclodextrin differ from each other and from those induced by beta cyclodextrin. C.p.-m.a.s. C-n.m.r. experiments showed that the cyclodextrin ring is probably more distorted in the flurbiprofen inclusion complex with methylated beta cyclodextrin than in that with beta cyclodextrin. 

VII = Heptakis (2,6-di-0-methyl-3-0-pentyl)--P--cyclodextrin + Octakis (2,6-di--0-methyl-3-0-trifluoroacetyl)-y-cyclodextrin... 

Bicchi C, Artuffo G, D Amato A, Manzin V, Galfl A, GaUi M, Cyclodextrin derivatives in the GC separation of racemic mixtures of volatile compounds, Part V Heptakis 2,6-dimethyl-3-pentyl- 3-cyclodextrins,Chromatogr 15 710-714, 1992. 

B Chankvetadze, K Lomsadze, D Bergenthal, J Breitkreutz, K Bergander, G Blaschke. Mechanistic study on the opposite migration order of clenbuterol enantiomers in capillary electrophoresis with /3-cyclodextrin and single-isomer heptakis(2,3-diacetyl-6-sulfo-)-/3-cyclodextrin. Electrophoresis 22 3178-3184. 

Since tosyl group and bromide have the same efficiency as leaving groups, the synthesis in good yield of heptakis-6-thioglycosyl- cyclodextrin (17 e, 17f) from the heptakis(6-bromo-6-deoxy)- cyclodextrin (15c) needs, as expected, the sodium salts of 1-thiogalactose (16c, 16d) and high temperature (Scheme 6) [27]. 

Figure 15. Enantiomer separation of cis- and /ra . -i-etliyl-2-mcthylcyclohexane and cis- and Irons-1-methyl-2-propylcyclohexane on heptakis(2,3,6-tri-( -methyl)-/3-cyclodextrin in OV-1701 [0.07 M, 30 m x 0.25 mm (i.d.) fused silica capillary column, 50CC, 1.5 bar hydrogen]163.

Figure 18. Enantiomer separation of Q 2-1-mcthyl-2-(l-methylethenyl)cyclobutyl]ethyl trifluoroacetate (grandisol) and 2-chloroalkanes on heptakis(2,3,6-tri-0-pcntyl)- -cyclodextrin (42 m glass capillary column, 50 1 bar hydrogen)174.

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