Iterative two-step strategy for C2-C4′ linked poly-oxazole synthesis using Suzuki-Miyaura cross-coupling reaction

An iterative method for the synthesis of C2-C4′ linked poly-oxazoles has been developed. This efficient two-step repetitive process includes TBS-iodine exchange reaction and Suzuki-Miyaura cross-coupling reaction with oxazolylboronate 8, which allows appending a bis-oxazole moiety per each iteration. The synthesis of bis-, tris-, tetrakis-, pentakis-, and hexakis-oxazoles (10, 14, 22, 18, and 24) was achieved starting from the common intermediate 7 in 1-5 steps.     

An MO-theoretical calculation of solvent effect upon the NH3 + HF = NH4F reaction

An ab initia molecular orbital calculation was done as to a reacting system, NH₃+HF=NH₄F, with the inclusion of the solvent effect as the origin of dipolar field. The reactants were assumed to stay in dimers, (NH₃)₂ and (HF)₂, in advance to the reaction, and the respective partners of two reactants were regarded as point dipoles. The system was stabilized to some extent by two dipoles adopted. A study of configuration analysis on this system was made with and without the dipoles. Their effect was found to be favorable for proceeding of the reaction.     

Multichannel conduction in alkali silicate glasses

The qualitative change of the electrical conduction of alkali silicate glasses with alkali mixing is discussed in connection with dielectric and mechanical relaxation. The observed conduction is understood as the additive effect of two kinds of independent diffusion processes — I and II. In single alkali glass, diffusion process-I is always observed as the dominant conduction process. However, when one alkali is progressively substituted by another, the dominant conduction process is altered from diffusion process-I to II. In the mixed alkali glass containing equal amounts of two alkali ions, diffusion process-I disappears, so that only diffusion process-II is observed. Consequently, it becomes evident that the mixed alkali effect is not only the successive change of conductivity, but the alternation of the dominant conduction process.     

Efficient synthesis of poly(phenylazomethine) dendrons allowing access to higher generation dendrimers

We have developed a novel synthetic method of phenylazomethine dendrons that uses 4,4'-methylenedianiline instead of 4,4'-diaminobenzophenone to synthesize the precursor of the phenylazomethine dendron and then oxidized the precursor to the next-generation dendron. For this method, the productivity of the dendrons has been significantly increased. Furthermore, as the synthesis of high-generation dendrons becomes easier, synthesis of DPA G5 was achieved. [structure--see text]     

Regularized determinants for quantum field theories with fermions

A new type of regularized determinant for the ratio of two Dirac operators is presented. Some of its properties with application to the chiral anomaly are given.     

Wide control of proton conductivity in porous coordination polymers

The proton conductivities of the porous coordination polymers M(OH)(bdc-R) [H(2)bdc = 1,4-benzenedicarboxylic acid; M = Al, Fe; R = H, NH(2), OH, (COOH)(2)] were investigated under humid conditions. Good correlations among pK(a), proton conductivity, and activation energy were observed. Fe(OH)(bdc-(COOH)(2)), having carboxy group and the lowest pK(a), showed the highest proton conductivity and the lowest activation energy in this system. This is the first example in which proton conductivity has been widely controlled by substitution of ligand functional groups in an isostructural series.     

Palladium-catalyzed asymmetric allylic alkylation using chiral hydrazone ligands with ferrocene skeleton

Palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate (4) with a dimethyl malonate-BSA-LiOAc system has been successfully carried out in the presence of chiral phosphine-hydrazone ligands such as 3a in good yields with good enantioselectivities (up to 84% ee).     

Hadamard matrices of order 32 and extremal ternary self-dual codes

A ternary self-dual code can be constructed from a Hadamard matrix of order congruent to 8 modulo 12. In this paper, we show that the Paley–Hadamard matrix is the only Hadamard matrix of order 32 which gives an extremal self-dual code of length 64. This gives a coding theoretic characterization of the Paley–Hadamard matrix of order 32.