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991.
β-Cyclodextrin was immobilized on PEGylated Merrifield resin through cross-linking with 1,6-hexamethylene diisocyanate (HMDI) reagent, using conventional and microwave-assisted methodologies. FT-IR analysis of the solid intermediates indicated the attachment of the linker arm to the resin due the appearance of characteristic bands centered at 1716 and 2270 cm−1 and the attachment of cyclodextrin to the resin was accompanied with increased absorption at the OH stretching regions (3330-3400 cm−1). β-Cyclodextrin linked PEGylated resins are water insoluble and can be used to trap volatile organic compounds (VOCs) from water and subsequently be analyzed by headspace HS/GC, after simple filtration and drying steps. 相似文献
992.
Noriaki Miyake 《Journal of fluorine chemistry》2003,122(2):243-246
The utility of microreactor for the synthesis of α-fluoro-α,β-unsaturated esters, trifluoromethylation and Michael addition reaction, is described. 相似文献
993.
M. Somi Reddy 《Tetrahedron letters》2005,46(38):6437-6439
Aziridines are cleaved regioselectively with KSCN in the presence of β-cyclodextrin in water at room temperature with excellent yields. 相似文献
994.
Chengfu Xu 《Tetrahedron》2005,61(8):2169-2186
A simple and convenient method was reported for the preparation of optically active β-hydroxy-β-arylpropionates, δ-hydroxy-δ-aryl-β-oxo-pentanoates and their butyryl derivatives via CRL-catalyzed hydrolysis. The optically active products are potential precursors of some chiral pharmaceuticals and natural products. 相似文献
995.
Tomoko Yajima 《Tetrahedron》2005,61(43):10203-10215
The radical-mediated hydroxyalkylation of α,β-unsaturated esters with alkyl iodides, trialkylborane, water and KF in THF gave the corresponding α-hydroxy esters. The synthetic advantage of the method was demonstrated by a short-step total synthesis of (±)-tanikolide. 相似文献
996.
Pijus Kumar Mandal 《Tetrahedron letters》2005,46(21):3715-3718
Under acidic conditions, the N(1)-C(4) bond of 4-(4′-hydroxyphenyl)-azetidine-2-ones are cleaved with the formation of a stabilized benzylic carbocation intermediates. The intermediates were reduced by silanes or participated in intramolecular or intermolecular Friedel-Crafts reactions to produce tyrosine mimetics. 相似文献
997.
Masatoshi Mihara Yoshio Ishino Yoji Oderaotoshi Mitsuo Komatsu 《Tetrahedron letters》2005,46(47):8105-8108
A novel and efficient synthesis of 3,4,5-triaryltetrahydro-1,4-thiazine derivatives by treatment of β,β′-dichloro sulfides, 2:1 adducts of alkenes and sulfur dichloride, with aromatic amines in the presence of silica gel is described. The silica gel can be easily recovered and reused in up to four consecutive reactions without any significant decrease in product yield. 相似文献
998.
The crystal structures of the β-diketonate complexes Cu(pta)2, Cu(pta)2·EtOH, and Cu(F6-thd)2 (where pta is the anion of 1,1,1-trifluoro-5,5-dimethylhexane-2,4-dione and F6-thd is the anion of 2,2-bis(trifluoromethyl)-6,6-dimethylheptane-3,5-dione) were determined. The solid-state structures of Cu(pta)2 and Cu(F6-thd)2 are square planar, while Cu(pta)2·EtOH is approximately square pyramidal with the EtOH ligand occupying the apical position. In each case, only one geometrical isomer (cis or trans) was observed in the crystals; arguments are presented that both isomers are present in bulk samples. Calculations of molecular volumes for structurally related Cu(II) complexes containing non-fluorinated versus fluorinated ancillary ligands show that fluorine substitution does not significantly affect packing efficiency in the solid-state; however, solvent coordination decreases packing efficiency slightly. [Cu(tdf)(py)(μ-C3F7CO2)]2 (where tdf is the anion of 1,1,1,2,2,3,3,7,7,8,8,9,9,9-tetradecafluorononane-4,6-dionate), a derived impurity from preparations of Cu(tdf)2, was isolated in low yield. The copper coordination geometries in the centrosymmetric structure are intermediate between square pyramidal and trigonal bipyramidal, with two unsymmetrically bridging μ,η1:η1-C3F7CO2 ligands. 相似文献
999.
ObjectiveThis paper aimed to investigate ego modules for TGFβ3-induced chondrogenesis in mesenchymal stem cells (MSCs) using ego network algorithm.MethodsThe ego network algorithm comprised three parts, extracting differential expression network (DEN) based on gene expression data and protein-protein interaction (PPI) data; exploring ego genes by reweighting DEN; and searching ego modules by ego gene expansions. Subsequently, permutation test was carried out to evaluate the statistical significance of the ego modules. Finally, pathway enrichment analysis was conducted to investigate ego pathways enriched by the ego modules.ResultsA total of 15 ego genes were obtained from the DEN, such as PSMA4, HNRNPM and WDR77. Starting with each ego genes, 15 candidate modules were gained. When setting the thresholds of the area under the receiver operating characteristics curve (AUC) ≥0.9 and gene size ≥4, three ego modules (Module 3, Module 8 and Module 14) were identified, and all of them had statistical significances between normal and TGFβ3-induced chondrogenesis in MSCs. By mapping module genes to confirmed pathway database, their ego pathways were detected, Cdc20:Phospho-APC/C mediated degradation of Cyclin A for Module 3, Mitotic G1-G1/S phases for Module 8, and mRNA Splicing for Module 14.ConclusionsWe have successfully identified three ego modules, evaluated their statistical significances and investigated their functional enriched ego pathways. The findings might provide potential biomarkers and give great insights to reveal molecular mechanism underlying this process. 相似文献
1000.
The reversed-phased HPLC analysis of the methanol extract of the pericarp of C. taliera Roxb. (Talipalm), a rare species of Arecaceae family, afforded a new steroidal glycoside, β-sitosterol-3-O-α-l-rhamnopyranosyl-(1→4)-β-d-xylopyranosyl-(1→4)-β-d-glucopyranosyl-(1→4)-β-d-glucopyranoside (1). The structure of the compound was elucidated unequivocally by UV, IR, HR-ESI-MS, 1H and 13C NMR spectroscopic studies. 相似文献