Effect of light wavelength on photooxygenation of hexamethylbenzene

Irradiation of the charge transfer complex of hexamethylbenzene with oxygen at 313 nm in a mixture of methanol and benzene afforded methoxymethylpentamethylbenzene and methoxypentamethylbenzene.     

Ruthenium-catalyzed reactions of 1-cyclopropyl-2-propyn-1-ols with anilines and water via allenylidene intermediates: selective preparation of tri- and tetrasubstituted conjugated enynes

Ruthenium-catalyzed efficient preparation of the conjugated enynes can be carried out in the reactions of 1-cyclopropyl-2-propyn-1-ols with nitrogen- and oxygen-centered nucleophiles such as anilines and water in the presence of a catalytic amount of sulfur-bridged diruthenium complexes. The use of such complexes as catalysts realizes the completely stereoselective preparation of tri- and tetrasubstituted conjugated enynes, where ruthenium-allenylidene complexes work as key intermediates. The direct attack of nucleophiles on a cyclopropane ring connected to an allenylidene ligand is a key step to obtain the enynes stereoselectively.     

Design and evaluation of folate-appended methyl-��-cyclodextrin as a new antitumor agent

Methyl-??-cyclodextrin (M-??-CyD) is widely used as a raft disrupting agent through extraction of cholesterol from lipid rafts which are highly expressed in cell membranes of tumor cells, but it does not have tumor cell-selective action. Meanwhile, the widespread use of folic acid (FA) as a tumor-targeting ligand has been known, because folate receptor (FR) overexpresses in various kinds of epithelial tumor cells. In the present study, in order to obtain more tumor cell-selectivity and antitumor activity of M-??-CyD, we designed folate-appended M-??-CyD (FA-M-??-CyD), and evaluated its physicochemical properties and antitumor activity. The ¹H-NMR study demonstrated that FA-M-??-CyD having average degree of substitution of FA (DSF) of 1.0 was prepared. In addition, FA-M-??-CyD (DSF 1.0) was found to be amorphous in a solid state and surface-active. Importantly, FA-M-??-CyD (DSF 1.0) had potent cytotoxicity, compared to M-??-CyD in KB cells, but not in A549 cells. These results suggest that FA-M-??-CyD (DSF 1.0) has the potential as a novel antitumor agent.     

An analogue of the Dedekind–Rademacher sum and certain ray class invariants of real quadratic fields

In this paper, we consider a certain product of double sine functions as an analogue of the Dedekind–Rademacher sum. Its reciprocity formulas are established by decomposition of a certain double zeta function. As their applications, we reconstruct and refine a part of Arakawa?s work on ray class invariants of real quadratic fields, and prove directly explicit relations between various invariants which are defined in terms of the double sine function and are related to the Stark–Shintani conjecture. Moreover, in some examples, new expressions of the invariants are revealed. As two appendices, we give a new proof of Carlitz?s three-term relation for the Dedekind–Rademacher sum and a simple proof of Arakawa?s transformation formula for an analogue of the generalized Eisenstein series originated with Lewittes.     

Picosecond optical switching of a 1.5 μm active birefringent optical fiber loop filter using 1.3 μm control optical pulses and a 1.3 μm semiconductor optical amplifier

Less than 100ps, polarization-independent switching operation of an active birefringent optical fiber loop filter using 1.3 μm control optical pulses as well as a 1.3 μm semiconductor optical amplifier (SOA) has been demonstrated. In the proposed SOA-based active birefringent filter operating at 1.55 μm wavelength, 1.3 μm SOA is employed to control the polarization-mode dispersion in the loop part. By injecting 1.3 μm ps gain-switched optical control pulses into the SOA, 1.5 μm input signals can be switched from the transmission port to the reflection port with less than 100 ps rise time.     

Stereoselective synthesis of either (E)- or (Z)-silyl enol ether from the same acyclic α,β-unsaturated ketone using cationic rhodium complex-catalyzed 1,4-hydrosilylation

The stereoselective synthesis of either (E)- or (Z)-silyl enol ether from the same acyclic α,β-unsaturated ketone is reported. Highly (Z)-selective conditions were the use of [Rh(cod)₂]BF₄/DPPE at room temperature with no solvent, whereas (E)-selective conditions were the use of [Rh(cod)₂]BF₄/P(1-Nap)₃ (1-Nap = 1-naphthyl) under refluxing dichloromethane.     

Electrical conduction of bis(1,2-diondioximato)metals(II) and their partially oxidized complexes at high pressures

The resistivity of one-dimensional d⁸-metal complexes with various kinds of 1,2-diondioxime(dimethylglyoxime, nioxime, and diphenylglyoxime) ligands has been measured at high pressures. The resistivity of M(dmg)₂ and M(niox)₂ decreased with increasing pressure. The resistivity of M(dmg)₂ is much lower than that of M(niox)₂ at high pressure, though M-M distances and optical energy gaps in both salts are almost the same at atmospheric pressure. An anomalous low resistivity has been observed in Pt(dmg)₂ at about 40 kbar. The electrical resistivity of M(niox)₂ and M(dmg)₂, oxidized by oxidizing agents, decreased with increasing pressure. The resistivity of partially oxidized Pt complexes is significantly higher than that of the parent compounds at high pressure. On the contrary, partially oxidized Ni and Pd complexes are more conductive than unoxidized compounds at high pressures. The electrocal resistivity of unoxidized and partially oxidized Pt complexes increased with increasing pressure at higher pressures. The resistivity minimum at high pressure has been observed only in Pt complexes. The infrared spectra of the d⁸-metal complexes and their partially oxidized complexes have been investigated. The frequency of the CN stretching vibration in M(dmg)₂ and M(niox)₂ salts increases in the order Ni > Pd > Pt; on the other hand, the frequency of M(niox)₂X_n increases in the order Ni < Pd < Pt. The frequency of the CN stretching vibration is closely related to the effect of metal-ligand π1 back bonding in d⁸-metal complexes. Some anomalies in the resistance-pressure curve have been found in Ni(dpg)₂, Ni(dpg)₂I, Ni(dpg)₂I_0.5, and Ni(dpg)₂I_0.14. The anomalies are explained by new pressure-induced phase transitions.     

Three-dimensional shock wave reflection over a corner of two intersecting wedges

This paper presents an experimental and numerical investigation of three-dimensional shock wave reflections over a corner of two wedges intersecting perpendicularly in a shock tube. Experiments were conducted in a diaphragmless shock tube equipped with double-exposure diffuse holographic interferometry in which the time interval between the first and second exposure was set to be . This arrangement clearly visualized complex configurations of three-dimensional shock wave reflections. A numerical study was also carried out for interpreting these holographic interferometric observations by using the Weighted Average Flux (WAF) method to solve the three-dimensional unsteady compressible Euler equations. It was found that along the line of the intersection of these two wedges, two Mach stems intersected each other resulting in the formation of a Mach stem which leaned forward. Received 30 June 1996 / Accepted 6 October 1996