Synthesis of fluspidine via asymmetric NaBH4 reduction of silicon enolates of β-keto esters

Asymmetric NaBH₄ reduction catalyzed by the Co(II) complex of a chiral diamidine-type sp²N ligand, Naph-diPIM-dioxo-iPr, was successfully applied to 3-silyloxycinnamate substrates without over-reduction, giving quantitatively 3-silyloxy-3-arylpropionates with an enantiomer ratio of up to 99:1. The high utility was confirmed on a 30-g scale using 0.1?mol% catalyst. Both Z and E substrates could be converted to a single enantiomeric product by changing the ligand chirality. The relationship between the Z/E stereochemistry and the absolute configuration of the 1,4-reduction product provided important information about the mechanism underlying enantioface selection. Combination of the asymmetric catalysis with two other key steps, Suzuki coupling with an N-protected tetrahydropyridine boronic acid derivative and intramolecular bromo etherification, realized an efficient synthetic route to both enantiomers of fluspidine. The new strategy permits the introduction of substituents on the two aryl groups and piperidine ring, allowing for structural variations toward the development of higher performance σ1 receptor antagonists.     

A Direct S0→Tn Transition in the Photoreaction of Heavy-Atom-Containing Molecules

According to the Grotthuss–Draper law, light must be absorbed by a substrate to initiate a photoreaction. There have been several reports, however, on the promotion of photoreactions using hypervalent iodine during irradiation with light from a non-absorbing region. This contradiction gave rise to a mystery regarding photoreactions involving hypervalent iodine. We demonstrated that the photoactivation of hypervalent iodine with light from the apparently non-absorbing region proceeds via a direct S₀→T_n transition, which has been considered a forbidden process. Spectroscopic, computational, and synthetic experimental results support this conclusion. Moreover, the photoactivation mode could be extended to monovalent iodine and bromine, as well as bismuth(III)-containing molecules, providing new possibilities for studying photoreactions that involve heavy-atom-containing molecules.     

Disjoint weighing matrices

Journal of Algebraic Combinatorics - The notion of disjoint weighing matrices is introduced as a generalization of orthogonal designs. A recursive construction along with a computer search leads to...     

Topological theory for Selberg type integral associated with rigid Fuchsian systems

Using the analytic realization of middle convolution due to Dettweiler and Reiter, we show that any rigid Fuchsian system can be obtained as a subsystem of some generating system which has an integral representation of solutions of Selberg type. Twisted homology groups and twisted cohomology groups associated with such integrals are studied. In particular, contiguity relations and twisted cycles which realize local exponents are obtained.     

Ion transport in mesoporous silica SBA-16 thin films with 3D cubic structures

Mesoporous silica SBA-16 thin films with highly ordered 3D cubic structures were synthesized on a Si substrate via the dip-coating method. After these films were filled with KCl aqueous solutions, the ionic current passing through the mesopores was measured by applying dc electric fields. At low ion concentrations, the measured I-V curves were nonlinear and the current increased exponentially with respect to voltage. As the ion concentration increased, the I-V curve approached linear behavior. The nonlinear behavior of I-V curves can be reasonably attributed to the electric potential barrier created in nanopores.     

p-adic Siegel–Eisenstein series of degree two

We prove an explicit formula for Fourier coefficients of Siegel–Eisenstein series of degree two with a primitive character of any conductor. Moreover, we prove that there exists the p-adic analytic family which consists of Siegel–Eisenstein series of degree two and a certain p-adic limit of Siegel–Eisenstein series of degree two is actually a Siegel–Eisenstein series of degree two.     

General Moments of the Inverse Real Wishart Distribution and Orthogonal Weingarten Functions

We study a random positive definite symmetric matrix distributed according to a real Wishart distribution. We compute general moments of the random matrix and of its inverse explicitly. To do so, we employ the orthogonal Weingarten function, which was recently introduced in the study of Haar-distributed orthogonal matrices. As applications, we give formulas for moments of traces of a Wishart matrix and its inverse.     

Synthesis and Biological Activity of Some New Pyrazole Copper(II) Complexes

As a part of systematic investigation of synthesis and biologically active compounds of pyrazole derivatives containing transition metal, several new pyrazole copper(II) complexes 3a?f were synthesized from pyrazole sodium salts 2a?f , which were produced from spiro‐pyrazoles 1a?f and sodium hydride by a ring‐opening reaction. All the synthesized compounds were characterized by spectroscopic analysis. Pyrazole copper(II) complexes 3a?d and 3f exhibited high DNA cleavage activity in vitro. Furthermore, compounds 3a?f were tested for their growth inhibitory activity in A549 lung cancer, B16F10 murine melanoma, and HeLa human uterine carcinoma cells. Compounds 3c,d displayed moderate B16F10 and HeLa inhibitory activity levels ( 3c : IC₅₀ = 45 μM in B16F10 cells and 34 μM in HeLa cells, 3d : IC₅₀ = 50 μM in B16F10 cells and 32 μM in HeLa cells).     

Laser-plasma extreme ultraviolet source at 6.7?nm using a rotating cryogenic Xe target

A laser-plasma source comprising a rotating cryogenic solid-state Xe target has been studied for use in extreme ultraviolet lithography (EUVL) systems equipped with La/B₄C mirrors. The laser-to-EUV power conversion efficiency (CE) of the cryogenic Xe target was improved to achieve a maximum CE of 0.15?% at 6.7?nm with 0.6?% bandwidth. We successfully demonstrated the continuous generation of EUV light with an average power of 80?mW at 6.7?nm with 0.6?% bandwidth using a Nd:YAG slab laser at a repetition rate of 320?Hz and an average power of 100?W. Scaling-up of the laser-plasma source for use as a future EUVL source is also discussed.