Rüdiger W. Seidel

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The cyclic disulfide-bridged tetrapeptide cyclo(Boc-Cys-Pro-Gly-Cys-OMe) (1) was designed as a model for the study of solvent-driven conformational changes in peptides. The three-dimensional structure and dynamics of 1 were studied using a variety of experimental and computational techniques. The crystal structure of 1 reveals a β-turn stabilized by a(More)
For an overview of cyclodextrin chemistry, see: Atwood et al. (1996), Szejtli (1998). For applications of cyclodextrins, see: Del Valle (2004). For previous X-ray crystal structure determinations of various -cyclodextrin hydrates, see: Hamilton et al. (1968); Szejtli & Budai (1977); Lindner & Saenger (1978, 1982); Stezowski & Maclennan (1980); Fujiwara et(More)
The 2:1 sandwich-type complexes formed between a cyclopeptide with alternating L-proline and 6-aminopicolinic acid subunits and inorganic anions can be stabilized by covalently linking a tris-alkyne and a tris-azide derivative of this peptide through copper-catalyzed azide-alkyne cycloaddition. The resulting triply linked bis-cyclopeptide can interact with(More)
A distortion of the aromatic character and stabilization of the imino-form as a result of the protonation of 4-dimethylaminopyridine was established by IR-, UV- and 1H NMR-spectral analysis of 4-diaminopyridinium hydrogensquarate. Quantum chemical calculations were carried out at MP2 and B3LYP levels of theory and a 6-311++G** basis set with a view to(More)
Organozinc (ZnR with R = Cp*, Me, Cl, Br) ligated transition metal (M) half-sandwich compounds of general formula [Cp*M(ZnR)5] (M = Fe, Ru) are presented in this work. The new compounds were obtained by treatment of various GaCp* ligated precursors with suitable amounts of ZnMe2 to exchange Ga against Zn. This exchange follows a strict Ga:Zn ratio of 1:2.(More)
The bottom-up synthesis of organometallic zinc clusters is described. The cation {[Zn10](Cp*)6 Me}(+) (1) is obtained by reacting [Zn2 Cp*2] with [FeCp2][BAr4 (F)] in the presence of ZnMe2. In the presence of suitable ligands, the high reactivity of 1 enables the controlled abstraction of single Zn units, providing access to the lower-nuclearity clusters(More)
Acetic anhydride (ethanoic anhydride), (CH3CO)2O, is a widely used acetylation reagent in organic synthesis. The crystal and molecular structure, as determined by single-crystal X-ray analysis at 100 K, is reported for the first time. A crystal of the title compound (m.p. 200 K) suitable for X-ray diffraction was grown from the melt at low temperature. The(More)
The analogy between ZnR fragments and the hydrogen radical represents a fruitful concept in organometallic synthesis. The organozinc(ii) and -zinc(i) sources ZnMe2 (Me = methyl) and [Zn2Cp*2] (Cp* = pentamethylcyclopentadienyl) provide one-electron fragments ·ZnR (R = Me, Cp*), which can be trapped by transition metal complexes [L a M], yielding [L b (ZnR)(More)
Treatment of tetrakis(diethylamido)zirconium(IV); [Zr(NEt2)4] with a series of β-ketoimines ({[RHN]C(CH3)=C(H)C(CH3)=O} where R is a functionalized side-chain; 4-(2-methoxyethylamino)pent-3-en-2-one, Hmeap; 4-(3-methoxypropylamino)pent-3-en-2-one, Hmpap; 4-(2-(dimethylamino)ethylamino)pent-3-en-2-one, Hdeap; 4-(3-(dimethylamino)propylamino)pent-3-en-2-one,(More)
Zn-Cp* bond cleavage reactions leading to novel monovalent cationic zinc species are presented (Cp* = pentamethylcyclopentadienyl). The treatment of [Zn2Cp*2] with two equiv. of [H(Et2O)2][BAr4(F)] (BAr4(F) = B{C6H3(CF3)2}4) yields the triple-decker complex [Cp*3Zn4(Et2O)2][BAr4(F)] (1) via protolytic removal of a Cp* ligand as Cp*H, whereas the reaction(More)