Synthesis of Chiral Ionic Polymers Containing Quaternary Ammonium Sulfonate Structure and their Catalytic Activity in Asymmetric Alkylation

Repeated reaction between chiral quaternary ammonium dimer and disodium disulfonate gave the ionic polymer, which contains chiral quaternary ammonium sulfonate structure as a repeating unit. This chiral ionic polymer showed an excellent catalytic activity in asymmetric alkylation reaction. With the chiral ionic polymer catalysts, high level of enantioselectivities up to 97% ee were attained.     

Synthesis of Giant Zeolite Crystals by a Bulk-Material Dissolution Technique

Using a quartz glass tube as a bulk silica source under aqueous hydrothermal conditions afforded giant crystals of MFI zeolite about 3 mm in size (see photo). Similar procedures were successfully applied to bulk aluminosilicate ceramics to synthesize large crystals of other zeolites, such as ANA, JBW, CAN, and SOD.     

Site-selective photocycloadditions of 2-pyrones with electron-poor olefins and the derivation from the cycloadducts

Photosensitized cycloaddition of 4,6-dimethyl-2-pyrone ( 1 ) with methacrylonitrile ( 3b ) afforded two types of [2 + 2]cycloadducts, 4b and 6b , across the C₅-C₆ and C₃-C₄ double bonds in 1 , respectively. Photosensitized reactions of 1 with dimethyl maleate and dimethyl cyclobutene-1,2-dicarboxylate gave [2 + 2]cycload-ducts 4d, 4e across the C₅-C₆ double bond, in addition to [4 + 2]cycloadduct 9d or bicyclo[4.2.0]octadiene 10e . The photoreactions of methyl 2-pyrone-5-carboxylate ( 2 ) with 3b and 2-chloroacrylonitrile ( 3c ) gave [4 + 2]cycloadducts 5b, 5c in addition to [2 + 2]cycloadducts 11b and 11c across the C₅-C₆ double bond in 2 . The photocycloaddition mechanism was explained from results calculated by means of PM3-CI method. Namely, the site- and/or regio-selective products, 4, 5, 8, 9 and 10 were thought to come from the same site-selective radical intermediates in the case of electron-poor olefins. Pyrolysis and/or hydrolysis of the cycload-ducts 4e, 5b, 5c gave 5,6-dihydro-2-pyrone 12 or benzene derivatives.     

Nickel-catalyzed [4+3] cycloaddition of ethyl cyclopropylideneacetate and 1,3-dienes

The [4+3] cycloaddition of ethyl cyclopropylideneacetate (1) with 1,3-dienes proceeded in the presence of Ni(cod)₂-TOPP (tri-o-biphenylyl phosphite). The reaction provided a new method for the synthesis of cycloheptene derivatives. The mechanism of the reaction was proposed.     

Analysis by partial reflection spectrometry of protonated tetraphenylporphyrin adsorbed at a liquid-liquid interface

Visible reflection spectra of diprotonated meso-tetraphenylporphyrin adsorbates spontaneously formed at a dodecane-aqueous sulfuric acid interface have been measured using a home-made device comprising a prism-cell and variable-angle optics. The tilt angle of the pyrrole ring plane was estimated to be 47 degrees from the interface normal by use of an experimentally evaluated molecular density (1.20x10(-10) mol cm(-2)) of the diprotonated molecule in a monolayer form at the liquid-liquid interface. Positive and negative bands have been observed in the p-polarized partial internal reflection (p-PIR) spectra, whose band locations correspond to those in p-polarized external reflection (p-ER) spectra. Nevertheless, the bands in the p-PIR exhibited reversed sign to those of p-ER spectra. These suggest that the surface selection rule of the p-PIR spectrometry has a reversal rule of p-ER and p-PIR can also be used for the analysis of molecular orientation.     

Cubic phases of binary systems of 4′-n-tetradecyloxy-3′-nitrobiphenyl-4-carboxylic acid (ANBC-14)-n-alkane

The phase behaviour of the binary systems 4′- ⁿ -tetradecyloxy-3′-nitrobiphenyl-4-carboxylic acid (ANBC-14)- ⁿ -alkane ( ⁿ -tetradecane or ⁿ -hexadecane) was investigated by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. The phase behaviour was a function of temperature ( ^T ) and the effective carbon number of the system ( ^n*), where ^n* involves carbon atoms both from the alkoxy group of ANBC-14 and from the ⁿ -alkane added. ANBC-14 shows no cubic phase, but the addition of ⁿ -alkane induced cubic phases when ^n*≧c. 15. An interesting point is that the type of cubic phase is ^Ia 3 ^d for 15^≦n*≦17, while an ^Im 3 ^m type is formed for 18^≦n*≦20. Furthermore, for ^n* = 22, two types of cubic phase, one with ^Im 3 ^m symmetry in the low temperature region and the other with ^Ia 3 ^d in the high temperature region, were observed both on heating and cooling. The phase diagram with respect to ^T and ^n* is very similar to that of pure one-component ANBC- ⁿ , which is a function of ^T and the number of carbon atoms in the alkoxy group ⁿ .     

Tumescenamide C,an antimicrobial cyclic lipodepsipeptide from Streptomyces sp.

Tumescenamide C, a new cyclic lipodepsipeptide, was isolated from a culture broth of an actinomycete Streptomyces sp. KUSC_F05. Tumescenamide C was a congener of tumescenamides A and B, representing a sixteen-membered ring system, consisting of two proteinogenic and three non-proteinogenic amino acids, to which a methyl-branched fatty acid was attached. The planar structure was determined by spectroscopic analysis, while its absolute stereochemistry was determined by chemical degradation and asymmetric synthesis. Tumescenamide C exhibited antimicrobial activity with high selectivity against Streptomyces species.     

Study on adsorption behavior of cesium using ammonium tungstophosphate (AWP)-calcium alginate microcapsules

A functional microcapsule was prepared by encapsulating the fine crystalline ammonium tungstophosphate(AWP) in calcium alginate polymer(CaALG).The characterization of AWP-CaALG microcapsule was examined by SEM and EPMA.The adsorption behavior of Cs(I),Rb(I),Sr(II),Pd(II),Ru(III),Rh(III),La(III),Ce(III),Dy(III) and Zr(IV) was investigated by the batch method.The batch experiments were carried out by varying the shaking times,HNO 3 concentration,and initial concentration of metal ions.Relatively large K d values above 10 5 cm 3 /g for Cs(I) were obtained in the range of 0.1-5 M HNO 3,resulting in a separation factor of Cs/Rb exceeding 10 2.In contrast,the K d values of Sr(II),Pd(II),Ru(III),La(III),Dy(III),Ce(III) and Zr(IV) were considerably lower than 50 cm 3 /g.The K d value of Cs(I) decreased in the order of the coexisting ions,H + > Na + >> NH 4 +,and a linear relationship with a slop of about 1 was obtained between log K d and log [NH 4 + ]([NH 4 + ] > 0.01 M).The adsorption of Cs(I) was found to be controlled by chemisorption mechanism,and followed a Langmuir-type adsorption equation.A high uptake percentage of 99.4% for Cs(I) was obtained by using the dissolved solutions of spent fuel from FBR-JOYO(JAEA).     

Ginsenoside Rh2 Showing Ability to Induce Apoptosis in HeLa Cells

IntroductionApoptosis( programmed cell death,PCD) hasbeen shown to play an important role in multiplephysiological and pathological processes,such asembryonic development,homeostatic maintenanceof tissues and organs,maturation of the immunesystem,neurologic degeneration,autoimmune andinflammatory disease,atherosclerosis,oncogenesisand tumor progression[1— 4] .Ginsenoside G- Rh2 iso-lated from Panax ginseng belongs to protopanaxa-diol dammarene glycoside[5] .G- Rh2 has a suppres-sive effect…