Two new 15-deoxycimigenol-type and three new 24-epi-cimigenol-type glycosides from Cimicifuga Rhizome

Two new 15-deoxycimigenol-type (1, 2) and three new 24-epi-cimigenol-type glycosides (3-5) were isolated from Cimicifuga Rhizome, and the structures were elucidated on the basis of spectroscopic data including 2D NMR spectra and chemical evidence. The two new 15-deoxycimigenol-type glycosides were the first cimigenol-type glycosides lacking a hydroxyl group at C-15.     

Synthesis,properties, and gas permeability of novel poly(diarylacetylene) derivatives

Poly(diphenylacetylene)s having various silyl groups are soluble in common solvents, from whose membranes poly(diphenylacetylene) membranes can be obtained by desilylation. The oxygen permeability coefficients of the desilylated polymers are quite different from one another (120–3300 barrers) irrespective of the same polymer structure. When bulkier silyl groups are removed, the oxygen permeability increases to larger extents. Poly[1-aryl-2-p-(trimethylsilyl)phenylacetylene]s are soluble in common solvents, and afford free-standing membranes. These Si-containing polymer membranes are desilylated to give the membranes of poly[1-aryl-2-phenylacetylene]s. Both of the starting and desilylated polymers show very high thermal stability and high gas permeability. 1-Phenyl-2-p-(t-butyldimethylsiloxy)phenylacetylene polymerizes into a high-molecular-weight polymer. This polymer is soluble in common organic solvents to provide a free-standing membrane. Desilylation of this membrane yields a poly(diphenylacetylene) having free hydroxyl groups, which is the first example of a highly polar group-carrying poly(diphenylacetylene). The P/P and P/P permselectivity ratios of poly(1-phenyl-2-p-hydroxylphenylacetylene) membrane are as large as 47.8 and 45.8, respectively, while keeping relatively high P of 110 barrers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5028–5038, 2006     

Guerbet reaction of primary alcohols leading to beta-alkylated dimer alcohols catalyzed by iridium complexes

[IrCl(cod)]2 and [Cp*IrCl2]2 complexes catalyzed efficiently the Guerbet reaction of primary alcohols to beta-alkylated dimer alcohols in good yields. For instance, the reaction of 1-butanol in the presence of [Cp*IrCl2]2 (1 mol %), t-BuOK (40 mol %), and 1,7-octadiene (10 mol %) produced 2-ethyl-1-hexanol in 93% yield. Various primary alcohols undergo the Guerbet reaction under the influence of Ir complexes to give the corresponding dimer alcohols in good yields. This method provides an alternative direct route to beta-alkylated primary alcohols which are prepared by aldol condensation of aldehydes followed by hydrogenation.     

Analysis of lanthanide-induced NMR shifts of the Ce@C82 anion

The mapping of bond connectivity in the carbon cage of [Ce@C82]- and full assignment of the NMR lines were successfully achieved by means of 2D INADEQUATE NMR measurement. Paramagnetic NMR analysis shows that the Ce atom in [Ce@C82]- is located at an off-centered position adjacent to a hexagonal ring along the C2 axis of the C2v-C82 cage.     

One-Pot synthesis of gamma,delta-unsaturated carbonyl compounds from allyl alcohols and vinyl or isopropenyl acetates catalyzed by [IrCl(cod)]2

One-pot synthesis of gamma,delta-unsaturated carbonyl compounds from allyl alcohols and vinyl or isopropenyl acetates was achieved through in situ generation of allyl vinyl ethers by the action of the [IrCl(cod)]2 complex followed by Claisen rearrangement of the resulting ethers. For instance, the reaction of trans-2-methyl-3-phenyl-2-propen-1-ol with isopropenyl acetate in the presence of [IrCl(cod)]2 (1 mol %) and Cs2CO3 (5 mol %) at 100 degrees C for 3 h followed by 140 degrees C for 15 h afforded 5-methyl-4-phenyl-5-hexen-2-one in 72% yield. When vinyl acetate was employed in place of isopropenyl acetate, 4-methyl-3-phenyl-4-pentenal was obtained in 83% yield.     

Self-organized domain microstructures in a plate-like particle suspension subjected to rapid simple shear

The evolution of the microstructure and rheological properties of plate-like particle suspensions subjected to rapid simple shear is studied numerically. In response to the shear-induced strain, particles in the suspensions rearrange to form a steady-state microstructure, and the suspension viscosity reaches a steady value. Under this condition, the microstructure is composed of two domains having different particle fractions and particle orientations. In the matrix (particle-poor) and cluster (particle-rich) domains, the particles’ long axes are oriented subparallel to the shear plane and normal to the maximum compressive principal direction, respectively. A higher particle concentration and friction coefficient enhance the development of cluster domains relative to matrix domains leading the intensity of the preferred particle orientation to decrease and the number of contacting particles, the aspect ratio of clusters, the inter-particle force, and the suspension viscosity to increase. The domain microstructure is governed by two factors: (1) geometric relations between the particle orientation and the maximum compressive axes and (2) the magnitude of particle–fluid and particle–particle interactions. The first factor results in the coupling of the particle orientation and the local fraction of particles, which is an important character of the domain microstructure. The second factor controls the relative development of the cluster and matrix domains through the change in the particles’ rotational behavior. Our results suggest that the microstructure of plate-like suspensions subjected to rapid shear is predictable in terms of the cluster stability, which has important implications for the kinematics of flow-related microstructures in nature and manufacturing.     

Controlled sulfonation of poly(arylene ether sulfone)s and poly(arylene ether ketone)s with different molecular structures for polymer electrolyte membranes

Poly(arylene ether sulfone) copolymers derived from 9,9-bis(4-hydroxyphenyl)fluorene, bisphenol S and 4,4′-difluorodiphenylsulfone and poly(arylene ether ketone) copolymers derived from 4-phenoxybiphenyl, diphenyl ether and isophthaloyl chloride were prepared as precursor polymers for sulfonation reaction in which sulfonic groups are introduced quantitatively into specified positions. Sulfonation reaction for these two series of copolymers by concentrated sulfuric acid was successfully carried out to give sulfonated polymers with controlled positions and degree of sulfonation. Thermal stability, moisture absorption and proton conductivity for these two series of copolymers were measured and the results were compared to those of perfluorosulfonic acid polymers.     

Measurement of the 2H(p,n) Breakup Reaction at 170 MeV and the Three-Nucleon Force Effects

The effects of three nucleon force (3NF) have been actively studied via the nucleon–deuteron (Nd) scattering states. The differential cross sections and the vector analyzing powers A _y of the ²H(p, n) inclusive breakup reaction at 170 MeV were measured for the study of 3NF effects in the intermediate energy region. The polarized proton beam of 170 MeV was injected to the deuterated polyethylene (CD₂) target and the energy of scattered neutrons were measured by using TOF method. The data were compared with the Faddeev calculations based on modern nucleon–nucleon (NN) forces with and without the 3NF. Concerning the differential cross sections, we can see large discrepancies between the data and the calculations in the region of scattered neutron energies are low, which is similar to the results of the ²H(p, p) inclusive breakup reaction at 250 MeV.