Enzyme-based discrimination between clockwise and counterclockwise isomers of unsymmetrically disubstituted β-cyclodextrins. 6A,6B- and 6A,6G-derivatives

6A,6X-Dideoxy-6A-phenylthio-6X-[(β-naphthylsulfonyl)oxyl]-β-cyclodextrins (X=G and B) (5 and 6) were prepared together with the other isomers (X=C, D, E, and F) (1–4), isolated by reversed-phase column chromatography, and structurally assigned by use of Taka amylolysis.     

Phase segregation of LixMn2O4 (0.6<x<1) in non-equilibrium reduction processes

Chemical synthesis routes to Li_xMn₂O₄ (0.15≤x≤1) in non-equilibrium reduction processes were developed to carry out detailed structural analysis. Non-equilibrium Li_xMn₂O₄ (0.15≤x≤1) samples were prepared by chemical lithiation of λ-MnO₂ with LiI for 24 h; longer than 1 week was needed to reach true equilibrium at room temperature. The samples were characterized by X-ray diffraction analysis. The phase diagram was different from that in the equilibrium state; three cubic phases (phases A, B and C) were observed for Li_xMn₂O₄ (0.15≤x≤1). There were two regions of two-phase coexistence: the region of 0.25<x<0.55 (phase B+phase C) and 0.6<x<1.0 (phase A+phase B). In the compositional range of 0.6<x<1.0, the lattice constants of phases A and B change with the lithium composition, this indicates that it is a structural anomaly with a metastable two-phase character in non-equilibrium reduction processes.     

Different modes of cyclization in zoanthamine alkaloid system, bisaminal versus spiroketal formation

Bisaminal cyclization in the zoanthamine alkaloid system was strongly affected by the stereochemistry of the C4 methyl. While cyclization of the (4S)-methyl precursor gave only a bisaminal compound, cyclization of the (4R)-methyl isomer produced both spiroketal and bisaminal products.     

Estimation method for parameters of construction on predicting transmission loss of double leaf dry partition

For improving sound insulation of a double leaf dry partition, each leaf is often consisted of more than one panel. Previous study on predicting a transmission loss of double leaf partition, treats with the leaf varied just two kinds of panels and restricted to a leaf having same kind and same thickness. These restrictions are unfit for variety of current building materials and constructions. This study makes a prediction formula for a transmission loss of the double leaf partition with laminated leaves by a theoretical analysis and an experiment, and will discuss the predicted value with measured value in previous studies and catalogs.     

Factorization of Combinatorial R Matrices and Associated Cellular Automata

Solvable vertex models in statistical mechanics give rise to soliton cellular automata at q=0 in a ferromagnetic regime. By means of the crystal base theory we study a class of such automata associated with non-exceptional quantum affine algebras U′ $_q$ ( $\widehat {\mathfrak{g}}$ $_n$ ). Let B $_l$ be the crystal of the U′ $_q$ ( $\widehat {\mathfrak{g}}$ $_n$ )-module corresponding to the l-fold symmetric fusion of the vector representation. For any crystal of the form B = $B_{l_1 }$ ? ...? $B_{l_N }$ , we prove that the combinatorial R matrix B $_M$ ?B $\widetilde \to$ B?B $_M$ is factorized into a product of Weyl group operators in a certain domain if M is sufficiently large. It implies the factorization of certain transfer matrix at q=0, hence the time evolution in the associated cellular automata. The result generalizes the ball-moving algorithm in the box-ball systems.     

Synthesis of chemically stable PGI2 analogs II - synthesis of halogen substituted PGI2 analogs

Syntheses of several stable PGI₂ analogs substituted by halogen atoms(s) at C-5 or(and) C-7 are described. Reaction of protected PGI₂ methyl ester ( ) with -chlorosuccinimide gave 5-chloro-Δ⁶-PGI₁ derivative ( ), which was transformed into 5-chloro- and 5,7-dichloro-PGI₂ [( ) and ( )] by subsequent isomerization or chlorination. Similarly, reaction of with -bromosuccinimide gave 5-bromo-Δ⁶-PGI₁ derivative ( ), which was further transformed into 7-fluoro-PGI₂ ( ) by silver fluoride treatment. These halogenated PGI₂ analogs were found to be much more stable than PGI₂.     

Single-crystal growth of Tl2Ru2O7 pyrochlore using high-pressure and flux method

Single crystals of the thallium ruthenium pyrochlore have been grown by flux method under high oxygen pressure. The growth conditions were determined by direct observations using in situ powder X-ray diffraction (XRD) method under high pressure and high temperature. The crystals were grown using NaCl-KCl flux at 1350 °C and B₂O₃ flux at 1150 °C. High growth temperature of 1350 °C for the NaCl-KCl flux caused Pt contamination from the crucible and oxygen deficiency for the crystals obtained. The crystal growth using B₂O₃ flux proceeded at lower temperature by grain growth with material transfer through B₂O₃. The crystal obtained was characterized by single-crystal XRD method, and was found to have a stoichiometric composition, Tl₂Ru₂O_7−δ (δ=0), with a structural phase transition around 120 K. The grain growth technique with B₂O₃ is efficient for high-temperature single-crystal growth under high pressure.     

Towards the development of synthetic routes using theoretical calculations: an application of in silico screening to 2,6-dimethylchroman-4-one

This study describes an attempt to develop a synthetic route using theoretical calculations, i.e., in silico synthesis route development. The KOSP program created four potential synthetic routes for generating 2,6-dimethylchroman-4-one. In silico screening of these four synthetic routes was then performed. In silico screening involves theoretical analysis of synthetic routes prior to actual experimental work. A synthetic route using the Mitsunobu reaction had already been reported by Hoddgets et al. Theoretical investigations were also conducted on two S(N)Ar reactions as well as a Michael reaction before they were examined experimentally. In silico screening using DFT calculations indicated that only the Michael reaction was likely to produce the target. Experimental work confirmed that the target was obtained in a yield of 76.4% using the Michael reaction. The other two routes, except for the Mitsunobu reaction, failed to generate the target. Our results demonstrate that theoretical calculations can be used to narrow down the number of experiments that need to be conducted when developing novel synthetic routes.