Twofold Brook rearrangement-mediated tandem reactions of δ-silyl-γ,δ-epoxy-α,β-unsaturated acylsilanes with a cyanide ion

Reaction of δ-silyl-γ,δ-epoxy-α,β-unsaturated acylsilanes with KCN in the presence of chloro or cyanoformates gives highly functionalized dienol silyl ether derivatives via a twofold Brook rearrangement-induced tandem sequence.     

Preparation of Layer Structure-Controlled Ru-Sn-Al2O3 Catalysts and Their Reactivity

In order to achieve functional group selective hydrogenation, the layer structure of Ru-Sn-Al2O3 catalysts was controlled by using sol-gel, powder impregnation and combined sol-gel impregnation methods. The properties of the catalysts and effectiveness in hydrogenation of dimethyl terephthalate were examined. The surface Sn contents of the catalysts characterized by X-ray photoelectron spectroscopy depended on the preparation method, in spite of almost the same bulk Ru and Sn compositions measured by X-ray fluorescence analyses. TPR and CO adsorption of the catalysts also depended on the preparation method. With regard to the conversion rate of dimethyl terephthalate and the rate of product conversion from methyl 4-hydroxy methylbenzoate to p-xylene via methyl p-toluate, Ru impregnation catalysts had higher rates than the other catalysts.     

Electrochemical detection of lectin using a galactosamine labeled with daunomycin

To detect a lectin from soybean, an electrochemical procedure was developed by the use of a labeling of galactosamine. Because the lectin has binding sites to galactosamine, galactosamine labeled with daunomycin having electroactivity was prepared. When labeled galactosamine (LG) combines with lectin, the part of daunomycin is taken in the binding sites of the lectin and becomes electroinactive. Therefore, the concentration of the lectin can be estimated by measuring the peak current of the LG. On the other hand, a competitive reaction to the lectin of galactosamine and the LG makes a detection of galactosamine possible. This method has merit that does not require a separation procedure of the free LG from the bound one. An effect of length of spacer between daunomycin and galactosamine was also investigated. It was found that adsorption of reagent on the electrode increased due to introduction of the spacer. Furthermore, the electrode response of the LG was influenced by the type of the spacer.     

Reaction stoichiometry for coextraction of technetium(VII) with uranium(VI) by CMPO

The coextraction equilibrium of technetium(VII) and uranium(VI) from nictric acid solution was studied in a system involvingn-octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO) in decalin. Stoichiometry of technetium, uranium and CMPO in the Tc-U-CMPO complex was obtained from the distribution data by slope analysis. The results indicated that the enhanced extraction of technetium was caused by the formation of UO₂NO₃TcO₄·nCMPO (wheren=2 and/or 3). It was found that this coextraction of technetium with uranium was well explained by using ion exchange reaction between UO₂(NO₃)₂·2CMPO complex and TcO ₄ ^– .     

Measurements of short-lived cosmogenic nuclides in rain samples

Summary Extremely low activity levels of cosmic ray induced nuclides have been measured in freshly precipitated rainwater by quick chemical separation coupled with ultra low background gamma-spectrometry. The nuclides detected were ³⁸S (T_1/2 = 2.83 h)-³⁸Cl (37.2 m), ³⁹Cl (55.6 m), ²⁴Na (14.96 h), ²⁸Mg (20.9 h), ⁷Be (53.3 d) and ²²Na (2.602 y). The number of atoms in rain water were evaluated to be ranging from 400-1900 l^-1 for ³⁹Cl (n = 6, mean: 1200), 30-1500 l^-1 for ²⁴Na (n = 16, mean: 520), 80-600 l^-1 for ²⁸Mg (n = 13, mean: 260), 1 ^. 10⁶-4 ^. 10⁷ l^-1 for 7Be (n = 16, mean: 7 ^. 10⁶) and 2 ^. 10³-1 ^. 10⁵ l^-1 for ²²Na (n = 9, mean: 2 ^. 10⁴). Measurements of activity levels and activity ratios of short-lived cosmic-ray induced short-lived nuclides will open new method to understand atmospheric processes occurred at the altitude of rain cloud.     

Nonpeptide arginine vasopressin antagonists for both V1A and V2 receptors: synthesis and pharmacological properties of 4-(1,4,5,6-tetrahydroimidazo[4,5-d][1]benzoazepine-6-carbonyl)benzanili de derivatives and 4'-(5,6-dihydro-4H-thiazolo[5,4-d][1]benzoazepine-6-carbonyl)benzanilid e derivatives

Arginine vasopressin (AVP) has a dual action mainly in the periphery, i.e., vasoconstriction and water reabsorption via V1A and V2 receptors; it may play a role in a number of diseases, including congestive heart failure (CHF), hypertension, renal disease, edema, and hyponatremia. We have attempted to develop a new series of orally active AVP antagonists for both V1A and V2 receptors based on the hypothesis that the blockade of both V1A and V2 receptors might be beneficial to CHF patients. In this report, a series of compounds structurally related to 4'-(1,4,5,6-tetrahydroimidazo[4,5-d][1]benzoazepine-6- carbonyl)benzanilide and 4'-(5,6-dihydro-4H- thiazolo[5,4-d][1]benzoazepine-6-carbonyl)benzanilide were synthesized and examined for AVP antagonist activity for both V1A and V2 receptors. As a result, it was found that the 4'-(1,4,5,6-tetrahydroimidazo[4,5-d][1]benzoazepine-6-carbon yl)-2- phenylbenzanilide derivatives showed potent binding affinity for both V1A and V2 receptors. Especially, 4'-(2-methyl-1,4,5,6- tetrahydroimidazo[4,5-d][1]benzoazepine-6-carbonyl)-2-phe nylbenzanilide monohydrochloride (18, YM087 = conivaptan hydrochloride) exhibited potent binding affinity and AVP antagonist activity, after intravenous administration, for both V1A and V2 receptors. Furthermore, YM087 exhibited the most potent oral activity for the V2 receptor. Details of the synthesis and pharmacological properties of this series are presented.     

Practical asymmetric synthesis of (S)-MA20565, a wide-spectrum agricultural fungicide

A practical asymmetric synthesis of a wide-spectrum agricultural fungicide, (S)-MA20565 (1), is described. The convergent synthesis was achieved starting from commercially available 3-(trifluoromethyl)aniline (7) in 44% overall yield through five steps and 2-bromobenzaldehyde (9) in 48% overall yield through four steps, respectively. (S)-O-[1-(3-Trifluoromethylphenyl)ethyl]hydroxylamine (2), a key intermediate of 1, was prepared via ruthenium(II)-catalyzed asymmetric transfer hydrogenation of 1-(3-trifluoromethylphenyl)ethanone (6) followed by chlorination using methanesulfonyl chloride and oxyamination using potassium acetohydroxamate with high level of stereocontrol.     

Asymmetric halogenation and hydrohalogenation oftrans-cinnamic acid in crystalline cyclodextrin complexes

Asymmetric halogenation and hydrohalogenation oftrans-cinnamic acid have been achieved in the microcrystals of cyclodextrin complexes. The bromination of the organic acid in the cavity of -cyclodextrin gave theerythro-dibromide in 40 % optical yield which was much larger than that from the resolution treatment of the racemic dibromide with -cyclodextrin and the absolute configuration was opposite in sign. The asymmetric induction in the gas-solid reaction was not due to optical resolution but to the reaction itself which was influenced by the chiral frame of cyclodextrin. The reaction shows the molecular size effect that the acid in the cavity of -cyclodextrin reacted with smaller hydrogen bromide but did not with larger bromine and chlorine. In contrast, the guest molecule in the wider cavity of -cyclodextrin reacted with bromine and chlorine as well as hydrogen bromide. The stereospecificities of the gas-solid halogenations of the acid in -cyclodextrin were similar to those of the both reactions in the solid state and in carbon tetrachloride solution without -cyclodextrin: bromination of the acid yieldederythro-2, 3-dibromo-3-phenylpropionic acid stereospecifically in 100 % in three different conditions, but chlorination gave an excess ofthreo-2, 3-dichloro-3-phenylpropionic acid to theerythro-isomer in 7287 % yields.     

The study of electron beam flue gas treatment for coal-fired thermal plant in Japan

The fundamental research work with simulated coal-fired flue gas was performed in JAERI to get basic data for electron beam treatment of flue gas from thermal power plants in Japan. The standard condition of the experiments was set to be the same as that of next large scale pilot test in Nagoya. The concentrations of NO_x and SO_x were 225 ppm and 800 ppm, respectively. The temperature of the system was 65°C. The effect of multiple irradiation was observed for NO_x removal. The target SO_x and NO_x removals (94% and 80%, respectively) with low NH₃ leakage (less than 10 ppm) were achieved at 9 kGy irradiation with 0.9 NH₃ stoichiometry during 7 hours continuous operation. The facility for the pilot plant (12,000 Nm³/hr) has just built at the site of Shin-Nagoya power plant of Chubu Electric Power Company and will be started in full operation in November 1992.     

Synthetic studies on (−)-FR182877: construction of the ABCD ring system via the intramolecular cycloadditions (2)

Construction of the ABCD ring system of (−)-FR182877 via the intramolecular Diels-Alder (IMDA) reaction and the highly diastereoselective intramolecular hetero-Diels-Alder (IMHDA) reaction is described. The IMHDA reactions of the substrates incorporating the oxabutadiene with the E- or Z-alkene were examined, revealing that the sole product was obtained from both substrates and the E-alkene geometry was found to be crucial to obtaining the desired product.