Peroxycarbenium-mediated C-C bond formation: applications to the synthesis of hydroperoxides and peroxides

The Lewis acid-mediated reaction of alkene nucleophiles with peroxyacetals provides an effective route for the synthesis of homologated peroxides and hydroperoxides. In the presence of Lewis acids such as TiCl(4), SnCl(4), and trimethylsilyl triflate, peroxyacetals and peroxyketals undergo reaction with allyltrimethylsilane, silyl enol ethers, and silyl ketene acetals to afford homoallyl peroxides, 3-peroxyketones, and 3-peroxyalkanoates, respectively. Reactions of peroxyacetals are Lewis acid dependent; TiCl(4) promotes formation of ethers while SnCl(4) and trimethylsilyl triflate promote formation of peroxides. Lewis acid-promoted reactions of silylated hydroperoxyacetals furnish silylated hydroperoxides, which can be deprotected to homologated hydroperoxides. Hydroperoxyketals undergo Lewis acid-mediated allylation to furnish 1,2-dioxolanes via attack of hydroperoxide on the intermediate carbocation. Lewis acid-mediated cyclization of unsaturated peroxyacetals furnishes 1,2-dioxanes, 1,2-dioxepanes, and 1,2-dioxacanes through 6-endo/exo, 7-endo/endo, and 8-endo/endo pathways. The corresponding reactions involving 6-endo/endo and 5-endo/exo pathways were unsuccessful.     

Solvent-free synthesis,x-ray studies and in vitro inhibitory activities of copper(II) complexes of non-steroidal anti-inflammatory drugs

Solid-state mechanochemical synthesis of [Cu(CAF)₂(H₂O)(OAc)]OAc complex 1a and [Cu(COD)₂(H₂O)(OAc)]OAc complex 2a were obtained by grinding stoichiometric amounts of Cu(CH₃COO)₂·H₂O and corresponding non-steroidal anti-inflammatory drugs[(caffeine (CAF) and codeine(COD)], respectively, in a mortar with pestle. Solvent-based synthesis of 1b and 2b was also carried out by reaction of metal acetate salt and each drug by refluxing at 70 °C in CH₃OH for 1 h for comparison purposes. The complexes 1a and 2a were characterized by comparison of elemental analysis, FT-IR, UV–Vis and ¹H NMR spectra with those of the free ligand and solvent-based products (1b and 2b). The analytical and spectroscopic data of the complexes prepared via the two different methods are almost identical. X-ray diffraction patterns of the complexes prepared by mechanochemical method were different from that of the starting material suggesting formation of new metal complexes. In vitro inhibitory activities of both mechanochemical and solvent-based complexes were found to be higher than parent ligands, indicating that the antimicrobial effect of these drugs could be enhanced when they are chelated to the metal. The mechanochemical synthesis was carried out without the use of solvent or external heating. The method is faster and gives a higher yield than corresponding solvent-based reactions. The solid state reaction presented higher efficiency in terms of materials, energy and time compared to solvent-based synthesis.     

Synthesis and biological activities on metal complexes of 2,5-diamino-1,3,4-thiadiazole derived from semicarbazide hydrochloride

A bioactive ligand, 2,5-diamino-1,3,4-thiadiazole (L), derived from semicarbazide hydrochloride, and its metal complexes were prepared and characterized. The complexes were characterized using elemental, infra-red, ultraviolet/visible, magnetic moment, atomic absorption, thin layer chromatography and molar conductance measurements. The IR data revealed that the ligand (L) behaved as a tridentate neutral ligand. It coordinated to the metal ion via sulphur and nitrogen of the amines. The molar conductance data reveal that the chelates are non-electrolytes. From the Ultraviolet/Visible spectra and magnetic moment data, the complexes were found to have octahedral geometrical structure. In vivo evaluation of the antimicrobial activities of the metal complexes and the ligands showed greater activity against some micro-organisms when compared to the parent compounds. The chelates do not show toxicity against the activities of enzymes from homogenates of liver, kidney and serum in experimental rats.     

ICP-AES法测定色漆可溶性金属含量

用ICP-AES法测定了色漆中的“可溶性”金属铬、镉、铅元素，考察了不同酸度对分析结果的影响，优化了测试条件。进行了回收率和精密度试验。并用原子吸收光谱国标方法进行对照，结果一致。     

Great expectations: Specific lexical anticipation influences the processing of spoken language

Background  

Recently several studies have shown that people use contextual information to make predictions about the rest of the sentence or story as the text unfolds. Using event related potentials (ERPs) we tested whether these on-line predictions are based on a message-level representation of the discourse or on simple automatic activation by individual words. Subjects heard short stories that were highly constraining for one specific noun, or stories that were not specifically predictive but contained the same prime words as the predictive stories. To test whether listeners make specific predictions critical nouns were preceded by an adjective that was inflected according to, or in contrast with, the gender of the expected noun.