Pyrrolidine ring formation by a new base-promoted 1,3-dipolar cycloaddition of N-(phenylthiomethyl) amino acid esters

N-Phenylthiomethyl derivatives of α-amino acid esters are attacked by α,β-unsaturated carboxylates in the presence of sodium hydride, undergoing 1,3-dipolar cycloaddition to give pyrrolidines.     

Formic acid reduction—XVII : Kinetic studies on the formic acid reduction of N-benzylideneaniline

The formic acid reduction of azomethine which has been reported² to proceed nearly quantitatively by the use of the formate reagent, 5HCO₂H·2NEt₃, was kinetically investigated by the carbon dioxide trapping and UV spectroscopic methods, using N-benzylideneaniline as a representative. Rate data gave the rate equation, v = (k + k′ [NEt₃])[N-benzylideneaniline][HCO₂H], indicating two-path mechanism. By the technique of using deuterated formic acids, it was found that the hydrogen bound to the carbon of formic acid is transferred as hydride to the carbon of the CN double bond in the rate determining step. The reaction is facilitated by the electron-releasing substituents of the two benzene rings of N-benzylideneaniline. On the bases of these results a possible mechanism is proposed.     

Crystal structures of inclusion complexes of cholic acid with aniline,mono- and difluorinated anilines: Guest information expressed by molecular assembly

The crystal structures of cholic acid (CA), a naturally occurring bile acid, complexed with aniline, and its mono- and difluorinated derivatives were elucidated by X-ray crystallography. Comparison of the structures obtained shows that the molecular assembly pattern and the related structural change of the CA molecule vary among different complexes. These structural changes are the molecular information of the guests. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82197 (27 pages).     

Preparation and application of porous calcium fluoride—a novel fluorinating reagent and support of catalyst

A novel material, porous calcium fluoride (PCF) with more than 60 m²/g surface area, was prepared by the reaction of soda lime (SL) with anhydrous hydrogen fluoride (AHF), and its application as a fluorinating reagent and support of catalyst was investigated.     

The synthesis of benzophenothiazine derivatives

Summary The reaction of substituted 1,4-naphthoquinones with 2-aminothiophenol ando-aminoheterocyclic thiones in acidic condition afforded benzophenothiazin-5-one and azabenzophenothiazin-5-one derivatives, respectively.

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Die Synthese von Benzophenothiazin-Derivaten

Zusammenfassung Die Reaktion von substituierten 1,4-Naphthochinonen mit 2-Aminophenol bzw.o-aminoheterocyclischen Thionen führte unter sauren Bedingungen zu Benzophenothiazin-5-onen bzw. Azabenzophenothiazin-5-onen.

     

Isolation and synthesis of a new aromatic compound, brefelamide, from dictyostelium cellular slime molds and its inhibitory effect on the proliferation of astrocytoma cells

[structure: see text] We have explored the diversity of secondary metabolites produced by cellular slime molds to examine the possible use of such cellular slime molds as a resource for novel drug development. A new aromatic amide, brefelamide (1), was isolated from methanol extracts of the fruiting bodies of Dictyostelium brefeldianum and D. giganteum. The structure of 1 was determined by spectral means including EIMS and (1)H and (13)C NMR. The total synthesis of 1 was carried out to confirm the structure and obtain sufficient samples for performing biological evaluation. Interestingly, compound 1 inhibited the cellular proliferation of 1321N1 human astrocytoma cells.     

Chemical Functionalisation and Photoluminescence of Graphene Quantum Dots

Chemical modification of graphene quantum dots (GQDs) can influence their physical and chemical properties; hence, the investigation of the effect of organic functional groups on GQDs is of importance for developing GQD–organic hybrid materials. Three peripherally functionalised GQDs having a third‐generation dendritic wedge (GQD‐ 2 ), long alkyl chains (GQD‐ 3 ) and a polyhedral oligomeric silsesquioxane group (GQD‐ 4 ) were prepared by the Cu^I‐catalysed Huisgen cycloaddition reaction of GQD‐ 1 with organic azides. Cyclic voltammetry indicated that reduction occurred on the surfaces of GQD‐ 1 – 4 and on the five‐membered imide rings at the periphery, and this suggested that the functional groups distort the periphery by steric interactions between neighbouring functional groups. The HOMO–LUMO bandgaps of GQD‐ 1 – 4 were estimated to be approximately 2 eV, and their low‐lying LUMO levels (<?3.9 eV) were lower than that of phenyl‐C₆₁‐butyric acid methyl ester, an n‐type organic semiconductor. The solubility of GQD‐ 1 – 4 in organic solvents depends on the functional groups present. The functional groups likely cover the surfaces and periphery of the GQDs, and thus increase their affinity for solvent and avoid precipitation. Similar to GQD‐ 2 , both GQD‐ 3 and GQD‐ 4 emitted white light upon excitation at 360 nm. Size‐exclusion chromatography demonstrated that white‐light emission originates from the coexistence of differently sized GQDs that have different photoluminescence emission wavelengths.     

Segmented contracted basis sets for atoms H through Xe: Sapporo-(DK)-<Emphasis Type="Italic">n</Emphasis>ZP sets (<Emphasis Type="Italic">n</Emphasis> = D,T, Q)

For the 54 atoms from H to Xe, compact yet accurate segmented Gaussian-type basis sets have been constructed for all electron calculations. Non-relativistic nZP (Sapporo-nZP) sets for Li–Xe and relativistic nZP (Sapporo-DK-nZP) sets for K–Xe are developed (n = D, T, Q), which efficiently incorporate valence and core electron correlations. Test calculations at the coupled-cluster level of theory are performed for spectroscopic constants of 12 hydrides of s- and d-block atoms and 12 diatomics of p-block atoms in their ground states. For all molecules, the calculated spectroscopic constants approach to the experimental values smoothly as the basis set quality increases.