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1.
A palladium‐TPPTS catalyst heterogenized on KF/alumina has been shown to be effective and recyclable for the selective formation of monooctadienylxylopyranosides via the telomerization of butadiene with D ‐xylose. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
2.
Huricha Baigude Kaname Katsuraya Kohsaku Okuyama Kenichi Hatanaka Emi Ikeda Naokazu Shibata Toshiyuki Uryu 《Journal of polymer science. Part A, Polymer chemistry》2004,42(6):1400-1414
A novel sugar‐containing poly(ornithine) dendrimer is synthesized for possible antigen delivery and related applications. The dendrimer contains an ornithine dendron as interior scaffolding and oligosaccharides on the periphery, which provide an attachment site for a peptide antigen. Maltose or lactose is bound to both hemispherical and spherical poly(ornithine) dendrimer generation 3 (G3) by reductive amination between its reducing end and the peripheral amino group of the dendrimer using a borane‐pyridine complex in a buffer solution at 50 °C. The degree of substitution of sugar is changed by varying the molar ratio of sugar to dendrimer. When the surface of spherical poly(ornithine) dendrimer G3 is modified by binding β‐alanine to the 16 amino groups, highly substituted maltose‐ or lactose‐β‐alanine‐poly(ornithine) dendrimer G3 is obtained in high yield after 7 days of reaction. The structures of these sugar‐containing dendrimers are characterized by NMR and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry analyses. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1400–1414, 2004 相似文献
3.
The formation of the 28-membered ring cyclo[(6-amino-6-deoxy-d-galactonic acid)4] by cyclisation of a protected open chain fully hydroxylated nylon 6 linear tetramer in modest yield provides the first example of a new class of carbopeptoid-cyclodextrin. 相似文献
4.
We have carried out some photon interaction measurements using 59.54 keV γ-rays from a 241Am source. These include γ attenuation studies as well as photoelectric absorption studies in various samples. The attenuation
studies have been made using leaf and wood samples, samples like sand, sugar etc., which contain particles of varying sizes
as well as pellets and aqueous solutions of rare earth compounds. In the case of the leaf and wood samples, we have used the
γ-ray attenuation technique for the determination of the water content in fresh and dried samples. The variation of the attenuation
coefficient with particle size has been investigated for sand and sugar samples. The attenuation studies as well as the photoelectric
studies in the case of rare earth elements have been carried out on samples containing such elements whose K-absorption edge
energies lie below and close to the γ-energy used. Suitable compounds of the rare earth elements have been chosen as mixture
absorbers in these investigations. A narrow beam good geometry set-up was used for the attenuation measurements. A well-shielded
scattering geometry was used for the photoelectric measurements. The mixture rule was invoked to extract the values of the
mass attenuation coefficients for the elements from those of the corresponding compounds. The results are consistent with
theoretical values derived from the XCOM package. 相似文献
5.
An alternative method for anomeric deacetylation of fully acetylated carbohydrates has been developed using imidazole in methanol. 相似文献
6.
The molecular complex formation reactions of uridine (Urd) with adenosine (Ado), cytidine (Cyd), thymidine (Thd), adenosine 5-monophosphate (AMP) and cytidine 5-monophosphate (CMP) have been studied at 20°C. It was found that the main positive noncovalent centers of ion–dipole and dipole–dipole type interactions are the protonated N(3) atoms of Urd, whereas the negative centers are the endocyclic atoms of the bases characterized by high electron density from the second molecule involved in the reaction. Moreover, NMR results indicate the occurrence of stacking in the complex (Urd)H(Cyd), whereas in the complex, (Urd)H2(Thd), it is the only type of interaction. Deprotonation of the latter species brings about a change in the character of the reaction and ion–dipole interactions have been detected in the adduct, (Urd)H(Thd). Interestingly, no involvement of the phosphate groups in the formation of AMP and CMP adducts has been evidenced and the main centers of the reactions were found to be the N(7)and N(1) atoms of AMP, or the N(3) atoms of CMP and Urd. Moreover, in the Urd/CMP system the NMR results suggest stacking-type interactions. 相似文献
7.
EDTA—Cu配合物用于还原糖的测定 总被引:2,自引:0,他引:2
首次报道了应用EDTA(乙二胺四乙酸二钠盐)-铜配合物(EC)测定还原糖的分光光度法,结果表明,pH4~11时EC的最大吸收波长为732nm,在HCO-3CO2-3缓冲介质中,配合物EC的吸光度与还原糖在077~161mg(六碳糖)范围内有很好的线性关系,相关系数大于0998,样品测定回收率在95%~105%之间。该法试剂易得、性质稳定,操作方便,灵敏度较高,取样量少于5mL。 相似文献
8.
E. V. Zhernosek S. V. Kvach L. A. Eroshevskaya E. N. Kalinichenko A. I. Zinchenko 《Chemistry of Natural Compounds》2006,42(2):208-211
Previously undescribed conjugates of 2′,3′-dideoxyuridine-5′-monophosphate-(L)-methoxytryptophylphosphoramidate (5) and 2′,3′-dideoxycytidine-5′-monophosphate-(L)-methoxytryptophylphosphoramidate (7) were isolated by a chemical enzymatic method in order to study their pharmacological properties and to prepare new medicinal
preparations based on them.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 173–175, March–April, 2006. 相似文献
9.
Polymer colloids based on 3‐O‐methacryloyl‐1,2:5,6‐di‐O‐isopropylidene‐α‐D ‐glucofuranose (3‐MDG) and butyl acrylate (BA) were prepared via free radical mini‐emulsion polymerization. The kinetic and colloidal features of the copolymerization were investigated. The final particle size (D) of the sugar latexes is inversely proportional to the concentration of the anionic emulsifier (sodium dodecyl sulphate, SDS) and the non‐ionic one (alkyl polyglucoside, APG). It was also found that D is independent of the concentration of either the water‐soluble initiator (potassium persulfate, KPS), or the oil‐soluble initiator (2,2′‐azobisisobutyronitrile, AIBN). The rate of mini‐emulsion polymerization is lower in comparison with the conventional emulsion polymerization under the same conditions. The polymerization rate (Rp) and the total number of particles (Np) are proportional to the 0.72th and 0.93th power of the SDS, and to the 1.40th and 2.22th of the APG concentration. Following reaction orders, 0.79/0.06 were obtained for Rp/Np versus the concentration of KPS, and 0.22/?0.01 for AIBN, respectively. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
10.
3-O-Acetyl-1,2-O-isopropylidene--D-allofuranose (2 b) was prepared from 1,2:5,6-di-O-isopropylidene--D-allofuranose (1 b). Treatment of2 b with triphenylphosphine-diethyl azodicarboxylate afforded regio- and stereospecifically the 5,6-epoxy--D-allo derivative (3). The other diastereomeric compound, 5,6-epoxy-1,2-O-isopropylidene--L-talofuranose (6) was also prepared stereoselectively from2 b
via the intermediates5 a and5 b. The epoxy sugars3 and6 were converted with lithium aluminum hydride to the corresponding 6-deoxy-1,2-O-isopropylidene--D-allofuranose (4 a) and --L-talofuranose (7 a) derivatives. Hydrolysis of4 a and7 a afforded 6-deoxy-D-allose and 6-deoxy-L-talose, respectively. The corresponding 3,5-di-O-acetyl- (4 b and7 b) and the 3,5-O-(tetraisopropyldisiloxane-1,3-diyl) derivatives (4 c and7 c) are also described. Selective removal of the isopropylidene group and subsequent acetylation offers a convenient route to prepare sugar derivatives containing furanose ring, like8 b, as a suitable precursor for nucleoside analogs.Herrn Prof. Dr.K. Komarek mit den besten Wünschen zum 60. Geburtstag gewidmet. 相似文献