Selective Propargylation of Carbonyl Compounds and Imines with Barium Reagents

A Barbier‐type regioselective propargylation of aldehydes and ketones with (3‐bromobut‐1‐ynyl)trimethylsilane has been achieved using reactive barium as a low‐valent metal in THF. Especially in the case of ketones, the corresponding homopropargylic alcohols form almost exclusively. In the reaction of α,β‐unsaturated carbonyl compounds, only 1,2‐adducts have been observed. This method is also applicable to propargylation of imines, and the corresponding homopropargylic amines are obtained regiospecifically in good yields with diastereomeric ratios of up to 87:13.     

Object recognition by use of polarimetric phase-shifting digital holography

Pattern recognition by use of polarimetric phase-shifting digital holography is presented. Using holography, the amplitude distribution and phase difference distribution between two orthogonal polarizations of three-dimensional (3D) or two-dimensional phase objects are obtained. This information contains both complex amplitude and polarimetric characteristics of the object, and it can be used for improving the discrimination capability of object recognition. Experimental results are presented to demonstrate the idea. To the best of our knowledge, this is the first report on 3D polarimetric recognition of objects using digital holography.     

Analysis of the pure-rotational spectrum in the ν28 = 1 excited torsional state and torsional couplings of trans-ethyl methyl ether

The trans-ethyl methyl ether molecule has three low-lying torsional modes, that is, two inequivalent methyl internal rotations and an asymmetric skeletal torsion. The internal rotations of the CCH₃ and OCH₃ methyl rotors and the skeletal torsion correspond to the vibrational modes, ν₂₈, ν₂₉ and ν₃₀ respectively. In this study, the microwave absorption spectrum in the ν₂₈ = 1 CCH₃ torsional state was analyzed for the first time. Nine hundred fifty seven lines up to J = 48 and K = 4 were assigned, and the rotational, centrifugal distortion and internal rotational tunneling parameters were determined with the use of a tunneling matrix formalism. By combining the present results on the ν₂₈ = 1 torsional state with those for the ν₃₀ = 1 skeletal torsional state and the ν₂₉ = 1 OCH₃ torsional state, torsional couplings are estimated in order to understand quantitatively the inverted A/E sequence patterns observed for those three excited torsional states.     

Reduction of thermal fluctuations in a cryogenic laser interferometric gravitational wave detector

The thermal fluctuation of mirror surfaces is the fundamental limitation for interferometric gravitational wave (GW) detectors. Here, we experimentally demonstrate for the first time a reduction in a mirror's thermal fluctuation in a GW detector with sapphire mirrors from the Cryogenic Laser Interferometer Observatory at 17 and 18 K. The detector sensitivity, which was limited by the mirror's thermal fluctuation at room temperature, was improved in the frequency range of 90 to 240 Hz by cooling the mirrors. The improved sensitivity reached a maximum of 2.2×10(-19) m/√Hz at 165 Hz.     

Abnormal Li diffusion in β-LiGa by the formation of defect complex

The diffusion coefficients of Li in the NaTl-type Li intermetallic compound of β-LiGa have been measured by using a short-lived radioactive diffusion tracer. As the tracer, the α-emitting radioisotope of ⁸Li delivered as the energetic and pulsed beam from Tokai Radioactive Ion Accelerator Complex (TRIAC) was implanted into the β-LiGa compounds with the composition in the range of about 43 to 54 at.% Li. By analyzing the time-dependent yields of the α-particles measured according to the repetition cycle of the beam, the tracer diffusion coefficients were extracted over the wide range of Li composition. Abnormal composition-dependence of Li diffusion coefficients in β-LiGa was observed; the stoichiometric β-LiGa showed the highest diffusivity of Li. By referring to the composition-dependent diffusivity of Li in the iso-structural β-LiAl and β-LiIn, we could identify the abnormal diffusion of Li in very Li-poor composition of β-LiGa. The anomaly has been discussed qualitatively in terms of the formation of defect complex and the interaction between the constitutional defects.     

Radical reaction of chlorophyll derivatives triggered by AIBN

Radical reactions of a C3-vinylated chlorophyll derivative, methyl pyropheophorbide-a, which were induced by thiols and the conventional initiator azobisisobutyronitrile (AIBN) were examined in vitro for the first time. Thiyl radicals attacked regioselectively at the sole C3-vinyl group, and the anti-Markovnikov sulfanyl adducts were obtained as major products. The other peripheral substituents, as well as the chlorin macrocycle, remained intact. The AIBN-induced radical reaction competed with co-oxidation that afforded the C3-formyl chlorin. This method can open new routes to derivatization of vinyl chlorins.     

Synthesis of 3‐Acyl‐4‐alkenylpyrrolidines by Platinum‐Catalyzed Hydrative Cyclization of Allenynes

A series of nitrogen‐tethered allenynes (‘5‐aza‐1,2‐dien‐7‐ynes’) 1 were transformed to the corresponding 3‐acyl‐4‐alkenylpyrrolidines 3 when treated with a catalytic amount of PtCl₂ in MeOH at 70°. Initial Pt‐promoted cyclization forms a nonclassical carbocationic intermediate. In contrast to the cycloisomerization in toluene, which produced the bicyclic cyclobutenes 2 , the intermediate is intercepted by addition of an oxygen nucleophile to achieve the formal hydrative cyclization.     

Freezing transition of wetting film of tetradecane on tetradecyltrimethylammonium bromide solutions

We have performed ellipsometry and surface tensiometry at tetradecyltrimethylammonium bromide (TTAB) aqueous solution surface coexisting with tetradecane lens as a function of the molality of TTAB and the temperature under atmospheric pressure. From the theoretical analysis of the coefficient of ellipticity, it was clarified that the liquid monolayer comprising the surfactant and alkane is formed at higher surfactant concentrations by the wetting transition of tetradecane lens on the aqueous solution, and the solid monolayer is formed by lowering temperature (freezing transition). The results of the surface tension measurement support the occurrence of wetting transition and the freezing transition. A phase diagram of the wetting film was constructed by ellipsometry and surface tensiometry, of which the mixed solid monolayer had never been reported before. From the thermodynamic analysis of the phase diagram, it is also demonstrated that the TTAB surface density decreases accompanied with the freezing transition, which agrees with surface densities of TTAB calculated from surface tension vs. concentration curves.