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41.
Thomas Daldrup Hatim Haddad und Constanze Heller 《Fresenius' Journal of Analytical Chemistry》1988,330(4-5):457-458
Ohne Zusammenfassung
Gas-chromatographic determination of volatile anesthetics (Enflurane and Isoflurane) with calibration by 1H-NMR-spectroscopy相似文献
42.
Glycoproteins on epithelial tumor cells often exhibit aberrant glycosylation profiles. The incomplete formation of the glycan side chains resulting from a down-regulated glucosamine transfer and a premature sialylation results in additional peptide epitopes, which become accessible to the immune system in mucin-type glycoproteins. These cancer-specific structure alterations are considered to be a promising basis for selective immunological attack on tumor cells. Among the tumor-associated saccharide antigens, the (2,3)-sialyl-T antigen has been identified as the most abundant glycan, found in several different carcinoma cell lines. According to a linear biomimetic strategy, the (2,3)-sialyl-T antigen was synthesized by a stepwise glycan chain extension of a protected galactosamine-threonine precursor. For the construction of immunostimulating antigens combining both peptide and saccharide motifs, this antigen was incorporated into glycopeptide partial structures from the mucins MUC1 and MUC4 by sequential solid-phase synthesis. 相似文献
43.
Benjamin R. Buckley Harry Heaney Edward P. Sampler Constanze Brocke 《Tetrahedron》2005,61(24):5876-5888
The synthesis of some chiral bis-(aminol)ethers are described. Reaction of a solution of the resorcin[4]arene derived from propanal with N,N-bis(methoxymethyl)-N-(S)-(−)-α-methylbenzylamine in toluene at 85 °C initially afforded a 1:1 mixture of two diastereoisomeric tetrakis(benzoxazines). Further, heating of this mixture under reflux in ethanol for 24 h afforded the crystalline (αS),(S)-diastereoisomer in 77% yield. N,N-bis(ethoxymethyl)-N-(S)-(−)-α-methylbenzylamine and N,N-bis(ethoxymethyl)-N-(R)-(+)-α-methylbenzylamine were reacted with β keto esters to afford a 1:1 mixture of the diastereoisomeric double Mannich adducts. Two of the double Mannich adducts were converted into tricyclic ABE analogues of the alkaloid methyllycaconitine 1. 相似文献
44.
A [RuRu] Analogue of an [FeFe]‐Hydrogenase Traps the Key Hydride Intermediate of the Catalytic Cycle
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Constanze Sommer Dr. Casseday P. Richers Prof. Dr. Wolfgang Lubitz Prof. Dr. Thomas B. Rauchfuss Dr. Edward J. Reijerse 《Angewandte Chemie (International ed. in English)》2018,57(19):5429-5432
The active site of the [FeFe]‐hydrogenases features a binuclear [2Fe]H sub‐cluster that contains a unique bridging amine moiety close to an exposed iron center. Heterolytic splitting of H2 results in the formation of a transient terminal hydride at this iron site, which, however is difficult to stabilize. We show that the hydride intermediate forms immediately when [2Fe]H is replaced with [2Ru]H analogues through artificial maturation. Outside the protein, the [2Ru]H analogues form bridging hydrides, which rearrange to terminal hydrides after insertion into the apo‐protein. H/D exchange of the hydride only occurs for [2Ru]H analogues containing the bridging amine moiety. 相似文献
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Dr. Theresa Liang Constanze N. Neumann Prof. Tobias Ritter 《Angewandte Chemie (International ed. in English)》2013,52(32):8214-8264
Over the past decade, the most significant, conceptual advances in the field of fluorination were enabled most prominently by organo‐ and transition‐metal catalysis. The most challenging transformation remains the formation of the parent C? F bond, primarily as a consequence of the high hydration energy of fluoride, strong metal—fluorine bonds, and highly polarized bonds to fluorine. Most fluorination reactions still lack generality, predictability, and cost‐efficiency. Despite all current limitations, modern fluorination methods have made fluorinated molecules more readily available than ever before and have begun to have an impact on research areas that do not require large amounts of material, such as drug discovery and positron emission tomography. This Review gives a brief summary of conventional fluorination reactions, including those reactions that introduce fluorinated functional groups, and focuses on modern developments in the field. 相似文献
47.
Ohne Zusammenfassung 相似文献
48.
We discuss the monoidal structure on Franke?s algebraic model for the K(p)-local stable homotopy category at odd primes and show that its Picard group is isomorphic to the integers. 相似文献
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We use dibutyl phosphate to simulate the behavior of the phosphate group in DNA towards the attack of low energy electrons. We find that the compound undergoes effective dissociative electron attachment within a low energy resonant feature at 1 eV and a further resonance peaking at 8 eV. The dissociative electron attachment (DEA) reactions are associated with the direct cleavage of the C-O and the P-O bond but also the excision of the PO-, PO3-, H2PO3- units. For the phosphate group coupled in the DNA network these reactions represent single strand breaks. We hence propose that the most direct mechanism of single strand breaks occurring in DNA at subexcitation energies (< 4 eV) is due to DEA directly to the phosphate group. 相似文献