共查询到20条相似文献,搜索用时 15 毫秒
1.
A. Bielejewska M. Ko
bia R. Nowakowski K. Duszczyk D. Sybilska 《Analytica chimica acta》1995,300(1-3)
The separation processes of α-, β- and γ-cyclodextrins and their various methyl derivatives have been investigated with Knauer polarimetric (Chiralyser) and refractive index (RI) detectors. RP18 and RP8 hydrocarbon packings and an NH2 bonded phase were applied as stationary phases. Aqueous methanolic or ethanolic solutions were used as mobile phases. It has been found that the Chiralyser detector response is approximately linear at low concentrations of solutes and that its detection capabilities are about 40 times better than those of the RI detector. Differences in the order of elution of α-, β- and γ-cyclodextrins have been observed for various stationary phases as well as for various mobile phase compositions. The optimal conditions for analytical determinations of cyclodextrins and their derivatives have been discussed. 相似文献
2.
Anna Domzalska-Pieczykolan Ignacio Funes-Ardoiz Bartomiej Furman Carsten Bolm 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2022,134(1):e202109801
We developed simple and efficient protocols for palladium-catalyzed regioselective α- and β-arylations of structurally diverse vinyl ethers. Both catalytic methods proceed under relatively mild reactions conditions applying to a broad substrate range including more complex compounds providing arylated glucal or isochromene. Lacking the common requirement of a large reagent excess, the transformations are highly economic and limiting the waste production. Results from computational studies (DFT) provided insight into the key factors determining the pronounced regioselectivities of the investigated reactions. 相似文献
3.
Dr. Stefanie Neubauer Dr. Florian Rechenmacher Dr. Ambros J. Beer Dr. Flavio Curnis Karolin Pohle Dr. Calogero D'Alessandria Prof. Dr. Hans‐Jürgen Wester Prof. Dr. Ute Reuning Prof. Dr. Angelo Corti Prof. Dr. Markus Schwaiger Prof. Dr. Horst Kessler 《Angewandte Chemie (International ed. in English)》2013,52(44):11656-11659
4.
5.
6.
The inclusion behavior between styrene (α-methyl styrene) and cyclodextrins (CDs) was studied by using 1H NMR titration in solution. The results indicate that 1:1 inclusion complexes were formed. The association constants of the inclusion complexes were determined by nonlinear least-square method. The inclusion process was also studied by using PM3 quantum-mechanical semi-empirical method. The calculated results are in agreed with the experimental data. 相似文献
7.
Fakhry Abdel-Aziz El-Bassiouny 《中国化学》1991,9(4):360-364
α- and β-Acetylnaphthalenes condensed with dimethyl β,β-dimethyl glutarate in the presence of sodium hydride to give the corresponding half-esters, the E-isomers 2a and 2b being predominant. The structure and configuration of the half-esters were characterized by chemical and spectroscopic means. 相似文献
8.
K. Jaques W. M. Buda M. Pottie J. Van der Eycken M. Vandewalle Arnold Venema Pat Sandra 《Journal of separation science》1993,16(12):703-707
The enantioseparation of some 2,2-dialkyl-4-alkoxycarbonyl-1,3-dioxolane derivatives, which are important intermediates in the total synthesis of a number of biologically active compounds, was studied by means of capillary gas chromatography (CGC). The chromatographic results, obtained on columns coated with permethylated α-, β- and γ-cyclodextrin respectively, are reported. Out of sixteen compounds, thirteen could be separated with a resolution superior to 1,2. One racemate could not be separated on any of the columns. Considerations concerning the separation mechanism are proposed. 相似文献
9.
Carbon-13 spectra of a series of 26 unsaturated ketones (ortho- and para-cyclo-hexadienones and corresponding open-chain analogues) have been measured by Fourier-transform. Pulse spectroscopy. A complete analysis has been achieved by means of double resonance experiments using noise-modulated and coherent off-resonance proton irradiation and with the aid of non-decoupled spectra. Chemical shifts are interpreted in terms of charge distribution in the dienone system and of methyl substituent effects. Carbon chemical shifts were also obtained for O-protonated ortho- and para-cyclohexadienones. One-bond and long-range carbon-proton and carbon-fluorine spin coupling constants are reported for several compounds. 相似文献
10.
Dr. Carlos Mas‐Moruno Roberta Fraioli Dr. Florian Rechenmacher Dr. Stefanie Neubauer Dr. Tobias G. Kapp Prof. Dr. Horst Kessler 《Angewandte Chemie (International ed. in English)》2016,55(25):7048-7067
Engineering biomaterials with integrin‐binding activity is a very powerful approach to promote cell adhesion, modulate cell behavior, and induce specific biological responses at the surface level. The aim of this Review is to illustrate the evolution of surface‐coating molecules in this field: from peptides and proteins with relatively low integrin‐binding activity and receptor selectivity to highly active and selective peptidomimetic ligands. In particular, we will bring into focus the difficult challenge of achieving selectivity between the two closely related integrin subtypes αvβ3 and α5β1. The functionalization of surfaces with such peptidomimetics opens the way for a new generation of highly specific cell‐instructive surfaces to dissect the biological role of integrin subtypes and for application in tissue engineering and regenerative medicine. 相似文献
11.
12.
13.
14.
15.
16.
17.
18.
K. Jaques W. Buda L. Dumortier J. Van der Eycken Arnold Venema Pat Sandra 《Journal of separation science》1994,17(2):72-73
Capillary GC on permethyl α-, β-, and γ-cyclodextrins has been applied to separate and quantify the enantiomers of some 2,3-iso-propylidene-1,2,3-cyclohexanetriol derivatives. Quantitative CGC data are compared to those obtained with chiral shift 1H NMR. 相似文献
19.