锌制剂“维宝康”治疗儿童缺锌综合征的临床研究

用维宝康治疗小儿缺锌综合征９８例,结果表明,服用维宝康一个疗程后,患者临床症状明显改善发锌值升高,总有效率为９６％,未见毒副作用,是较好的补锌制剂。     

Distance distributions and dynamics of a zinc finger peptide from fluorescence resonance energy transfer measurements

Time-resolved fluorescence resonance energy transfer (FRET) measurements were used to measure distance distributions and intramolecular dynamics (site-to-site diffusion) of a 28-residue single-domain zinc finger peptide in the absence and presence of zinc ion. Energy transfer was measured between TRP₁₄ and a N-terminal DNS group. As expected, the TRP-to-DNS distance distribution for zinc-bound peptide is shorter and narrower (R _av=11.2 Å,hw=2.8 Å) than the metal-free peptide (R _av=20.1 Å,hw=14.5 Å). The degree of mutual donor-to-acceptor diffusion (D) was also determined for these distributions. For zinc-bound peptide there is no detectible diffusion (D0.2 Ų/ns), whereas for metal-free peptide a considerable amount of motion is occurring between the donor and the acceptor (D=12 Ų/ns). These results indicate that the zinc-bound peptide folds into a unique, well-defined conformation, whereas the metal-free conformation is flexible and rapidly changing. The absence of detectible mutual site-to-site diffusion between the donor and the acceptor in the metal-bound zinc finger peptide indicates that intramolecular motion is essentially frozen out, on the FRET time scale, as a consequence of zinc coordination.Dedicated to the memory of Barbara D. Wells.     

The Route of Alkylation of 5-Substituted 1,3,4-Thiadiazoline-2-thiones

The reaction of 5-anilino(toluidino-, morpholino)-1,3,4-thiadiazoline-2-thiones at 80°C with allyl bromide and benzyl chloride in alcohol, acetonitrile or DMF in the presence of KOH and also with phenoxymethyloxirane in alcohol in the absence of base gives the corresponding novel allyl-, benzyl-, and 2-hydroxy-3-phenoxypropyl products substituted at the exocyclic S atom. Alkylation of the indicated thiones with benzyl chloride at 150-153°C in DMF in the presence of KOH occurs similarly. Under these conditions, allyl bromide forms alkylation products at the endocyclic N(3) atom as a result of an SN thio-Claisen rearrangement of the initially formed product which is allyl substituted at the exocyclic S atom.     

Spectrophotometric flow-injection determination of zinc in plant digests based on a spot test

A spot test was implemented in a flow-injection system for the spectrophotometric determination of zinc in digests of plant materials. It is based on the influence of Zn²⁺ on the oxidation rate of 1-naphthylethylenediamine (NED) by hexacyanoferrate(III) under acidic conditions. In order to control the precipitate formation and to maintain the resulting suspension, a micellar medium was established by adding Triton X-100. The proposed system handles about 65 samples per hour, meaning 72 μg NED and 9.0 mg K₃[Fe(CN)₆] per determination. Baseline drift is usually <0.01 absorbance per hour and the analytical signals for 0.5-2.5 mg l⁻¹ Zn range within ca. 0.07-0.45 absorbance. Linearity of the analytical curve is fair (r>0.999, n=6) and detection limit was estimated as 0.2 mg l⁻¹ Zn. Results are precise (R.S.D.<1%, n=10) and in agreement with flame atomic absorption spectrometry and with certified values of standard reference materials.     

Synthesis of organosilicon polymers by using the Lewis-acid-catalyzed trans-allylsilylation of alkynes

The HfCl₄ catalyzed polymerization of allyl(4-ethynylphenyl)dimethylsilane (1a) proceeded smoothly to give poly[dimethyl-(1,4-pentadienyl)phenylsilane] (2a), and the HfCl₄ catalyzed reaction of 1-allyl-2-(4-ethynyphenyl)-1,1,2,2-tetramethyldisilane (1b) afforded poly[1,1,2,2-tetramethyl-1-(1,4-pentadienyl)-2-phenyldisilane] (2b). These polymerization reactions proceeded via the stereoselective trans-allylsilylation of the 4-ethynyl group attached to the aromatic ring.     

Catalytic oxidation of thiols to disulfides using iodine and CeCl3·7H2O in graphite

A very simple procedure for the efficient oxidation of thiols to disulfides catalyzed by I₂/CeCl₃·7H₂O in graphite and ethyl acetate as the solvent, in an open system at room temperature is described. The reaction proceeds cleanly under mild conditions and was performed with aromatic, aliphatic, and heterocyclic thiols.     

Koordinative Verankerung von Nickelkomplexen an Hectorit-Schichtsilicaten mit Hilfe langkettiger Diphenylphosphinogruppen

Coordinative Anchoring of Nickel Complexes on Hectorite-Layer Silicates through long-chain Diphenylphosphine Groups The treatment of sodium and calcium hectorites with 2-diphenylphosphinoethyltriethoxysilane leads, by condensation of free hydroxyl groups, to functionalized layer silicates with long-chain diphenylphosphine groups onto which nickel chloride can be coordinated. In these modified hectorites the fourth coordination site of the tetrahedrally coordinated nickel is occupied by a labile solvent molecule. On the other hand, the complex bis(2-diphenylphosphinoethyltriethoxysilane)nickel(II) chloride prepared beforehand also reacts with sodium hectorite under condensation; but the square-planar coordination of the four stable ligands (two chloride and two phosphor atoms) is maintained. This finds its expression in a significant activity decrease in catalytic reactions as compared to the aforementioned products.     

小分子胺直接有效催化合成α-苯硒基酮

用有机小分子胺, 如辛可尼啶, L-脯胺酸和N-取代的手性1,2-环己二胺等直接催化酮与苯硒基氯反应, 通过这一简单有效的方法, 高收率合成了一些α-苯硒基酮.     

对硝基氯苄与活性亚甲基化合物的反应

对硝基苄基衍生物可以与许多阴离子起单电子转移的亲核取代反应。Kornblum等以对硝基氯苄为底物,2-乙氧羰基香豆满-3-酮的钠盐为阴离子,作了深入的研究,得出对硝基氯苄与2-乙氧羰基香豆满-3-酮钠盐的C-烷化反应机理为自由基链式亲核取代反应。同时,Russell等提出对硝基氯苄与2-     

Intramolecular electrophilic rearrangements in saturated acyclic systems. Reactivity of the zwitterion derived from triisopropylphosphine and ethyl 2-cyanoacrylate with respect to different types of electrophiles

The reactions of the zwitterion derived from triisopropylphosphine and ethyl 2-cyanoacrylate with mercuric chloride and aryl isothiocyanates containing Cl atoms in the ortho positions of the benzene ring follow an unusual pathway because this zwitterion represents latent triisopropylphosphine due to the reversibility of the reaction of triisopropylphosphine with ethyl 2-cyanoacrylate. The molecular structures of the adducts of triisopropylphosphine with 2,6-dichloro- and 2,4,6-trichlorophenyl isothiocyanates were confirmed by X-ray diffraction study. Protonation of the adduct of triisopropylphosphine with 2,6-dichlorophenyl isothiocyanate occurred at the nitrogen atom, whereas methylation with methyl trifluoromethanesulfonate afforded an S-methylation product. The results of X-ray diffraction study of the resulting compounds are presented.