The oxidative coupling of indole with some phenolic compounds,naphthols and catechols

The oxidative coupling of indole with three naphthols, 2-naphthol, 2,3-dihydroxynaphthalene and 2,7-dihydroxynaphthalene gave 1,1-bis(3′-indolyl)-2(1H)naphthalenone, 1,1-bis(3′-indolyl)-3-hydroxy-2(1H)naphthalenone and 1,1-bis(3′-indolyl)-7-hydroxy-2(1H)naphthalenone, respectively. The coupling of indole with protocatechuic aldehyde gave bis-(3-indolyl)-(3′,4′-di-hydroxyphenyl)methane and that of indole with homocatechol gave 3-(2′-methyl-3′,4′-di-hydroxyphenyl)indole.     

Optically active seleninamides: isolation, absolute configuration, and racemization mechanism

Optically active seleninamides were obtained for the first time by chromatographic resolution on an optically active column. The absolute configurations of the optically active seleninamides were determined by comparing their chiroptical properties with those of analogous sulfinamides, the stereochemistry of which was determined by transformation into chiral sulfoxides of known configurations. The optically active seleninamides were found to racemize in solution. Kinetic studies of the racemization and theoretical studies clarified that the racemization of the optically active seleninamides in solution proceeds via hypervalent hydrates formed by the reaction with water.     

Stereocontrolled total synthesis of potent immunosuppressant FR901483

A total synthesis of the potent immunosuppressant FR901483 (1) has been accomplished. The key feature of our convergent synthesis is the stereoselective incorporation of the p-methoxybenzyl and methylamino groups within the core moiety 10. Tricycle 10 was itself constructed by an intramolecular aldol reaction of the symmetrical keto-aldehyde 7. [Structure: see text]     

Himeradine A,a novel C27N3-type alkaloid from Lycopodium chinense

A novel C(27)N(3)-type Lycopodium alkaloid consisting of a fastigiatine-type skeleton (C(16)N(2)) and a quinolizidine moiety (C(11)N), himeradine A (1), has been isolated from the club moss Lycopodium chinense, and the structure and relative stereochemistry were elucidated on the basis of spectroscopic data.     

Precise synthesis of well‐defined dendrimer‐like star‐branched polymers by iterative methodology based on living anionic polymerization

Dendrimer‐like star‐branched polymers recently developed as a new class of hyperbranched polymers, which resemble well‐known dendrimers in branched architecture, but comprise polymer chains between junctions, are reviewed in this highlight article. In particular, we focus on the precise synthesis of various dendrimer‐like star‐branched polymers and block copolymers by the recently developed methodology based on iterative divergent approach using living anionic polymers and 1,1‐bis(3‐tert‐butyldimethylsilyloxymethylphenyl)ethylene. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6659–6687, 2006     

Colouring mechanism of dyed KDP crystal by quantum chemistry

Dye adsorption mechanism, in particular, colouring mechanism of KDP (KH₂PO₄) crystal was investigated by quantum chemistry in this study. Phenomena, such as different preferentially coloured faces of KDP when co-crystallised with different dyes, are explained by the minimum and maximum values of electrostatic potential (ESP). Furthermore, it is found that the ESP distribution of a dye molecule may not necessarily be the single mechanism affecting the dye adsorption in a crystal structure; and that the degree of protonation, crystal surface condition, steric exclusion of dye and the orientation of dye molecules situating on the crystal surface may as well be important factors for the dye adsorption.     

Probing the shape and stereochemistry of molecular orbitals in locally flexible aromatic chains: a penning ionization electron spectroscopy and Green's function study of the electronic structure of biphenyl

We report on the results of an exhaustive study of the interplay between the valence electronic structure, the topology and reactivity of orbitals, and the molecular structure of biphenyl by means of Penning ionization electron spectroscopy in the gas phase upon collision with metastable He*(2(3)S) atoms. The measurements are compared with one-particle Green's function calculations of one-electron and shake-up valence ionization spectra employing the third-order algebraic diagrammatic construction scheme [ADC(3)]. Penning ionization intensities are also analyzed by means of the exterior electron-density model and comparison with photoelectron spectra: in contrast with the lines originating from sigma orbitals, ionization lines belonging to the pi-band system have large Penning ionization cross sections due to their greater extent outside the molecular van der Waals surface. The involved chemi-ionization processes are further experimentally investigated using collision-energy-resolved Penning ionization electron spectroscopy. The cross sections of pi-ionization bands exhibit a markedly negative collision-energy dependence and indicate that the interaction potential that prevails between the molecule and the He*(2(3)S) atom is strongly attractive in the pi-orbital region. On the other hand, the partial ionization cross sections pertaining to sigma-ionization channels are characterized by more limited collision-energy dependencies, as a consequence of rather repulsive interactions within the sigma-orbital region. A comparison of ADC(3) simulations with the Penning ionization electron spectra and UV photoelectron spectra measured by Kubota et al. [Chem. Phys. Lett. 1980, 74, 409] on thin films of biphenyl deposited at 170 and 109 K on copper demonstrates that biphenyl molecules lying at the surface of polycrystalline layers adopt predominantly a planar configuration, whereas within an amorphous sample most molecules have twisted structures similar to those prevailing in the gas phase.     

Stability test and improvement of hydrogen analyzer with trace reduction detector

We previously developed an analyzer able to detect hydrogen concentrations of less than 50 cm3/1000 m3. The analyzer uses a carrier gas purifier and a low temperature separation column to remove impurities preventing measurement of low concentrations from the carrier and sample gases. It uses a trace reduction detector with a mercuric oxide bed to detect the concentration of hydrogen based on the reduction reaction of mercuric oxide with hydrogen. We have now evaluated the performance of the analyzer by carrying out a series of tests that measured the spectrum peak and the retention time. We used three sample gases with hydrogen concentrations of 5, 20, and 50 cm3/1000 m3 in nitrogen dilution gas. The measured peak was stable (it was within a relative standard deviation of less than 10%), and there was a linear relationship between the peak and hydrogen concentration. However, the retention time gradually shortened as the measurements were repeated. The shortening was reduced by warming the low temperature separation column used in the analyzer; it was not observed when we used a hydrogen sample gas diluted by helium instead of nitrogen. Using nitrogen as a dilution gas apparently shortens the retention time. We thus added an MS-5A separation column and a thermal conductivity detector. The nitrogen and hydrogen in the sample/carrier gas are separated, and the nitrogen is efficiently removed by switching the pass line to a release line after the hydrogen has been sent to the low temperature separation column. An analyzer using this "after-cut method" was able to stably measure infinitesimal hydrogen concentrations and was not affected by nitrogen in the sample gas.     

Enantioselective DNA alkylation by a pyrrole-imidazole S-CBI conjugate

Conjugates 12S and 12R of N-methylpyrrole (Py)-N-methylimidazole (Im) seven-ringed hairpin polyamide with both enantiomers of 1,2,9,9a-tetrahydrocyclopropa[1,2-c]benz[1,2-e]indol-4-one (CBI) were synthesized, and their DNA alkylating activity was examined. High-resolution denaturing gel electrophoresis revealed that 12S selectively and efficiently alkylated at one match sequence, 5'-TGACCA-3', in 450-bp DNA fragments. The selectivity and efficiency of the DNA alkylation by 12S were higher than those of the corresponding cyclopropapyrroloindole (CPI) conjugate, 11. In sharp contrast, another enantiomer, 12R, showed very weak DNA alkylating activity. Product analysis of the synthetic decanucleotide confirmed that the alkylating activity of 12S was comparable with 11 and that 12S had a significantly higher reactivity than 12R. The enantioselective reactivity of 12S and 12R is assumed to be due to the location of the alkylating cyclopropane ring of the CBI unit in the minor groove of the DNA duplex. Since the CBI unit can be synthesized from commercially available 1,3-naphthalenediol, the present results open up the possibility of large-scale synthesis of alkylating Py-Im polyamides for facilitating their use in future animal studies.     

Formation of GeO2 nanosheets using water thin layers in lamellar phase as a confined reaction field--in situ measurement of SAXS by synchrotron radiation

Highly crystallized GeO2 nanosheets were synthesized by hydrolysis and condensation reactions of germanium alkoxide using a 2-dimensional flat thin lamellar phase water layer containing surfactant molecules at the liquid-liquid interface as a confined reaction field.