Showing papers in "Chemistry Letters in 1984"
TL;DR: In this article, the intermolecular overlaps of the highest occupied molecular orbitals are calculated for α-(BEDT-TTF)2I3 reported by Bender et al.
Abstract: On the basis of the extended Huckel molecular orbital calculation, the intermolecular overlaps of the highest occupied molecular orbitals are calculated for α-(BEDT-TTF)2I3 reported by Bender et al., and for superconducting β-(BEDT-TTF)2I3 reported by Yagubskii et al. (BEDT-TTF: bis(ethylenedithio)tetrathiafulvalene). α-(BEDT-TTF)2I3 is a two-dimensional semimetal or a narrow gap semiconductor. β-(BEDT-TTF)2I3 is a two-dimensional metal which has an almost isotropic closed Fermi surface.
226 citations
TL;DR: In this paper, cellulose triacetate and tribenzoate coated on macroporous silica gel showed excellent capabilities of chiral recognition as packing materials for high performance liquid chromatographic resolution of various enantiomers.
Abstract: Cellulose triacetate and tribenzoate coated on macroporous silica gel showed excellent capabilities of chiral recognition as packing materials for high-performance liquid chromatographic resolution of various enantiomers. Chiral recognition by the cellulose triacetate was different from that by the microcrystalline cellulose triacetate.
164 citations
TL;DR: In this paper, a paramagnetic ruthenium(III) complex is prepared by the reaction of RuCl3·H2O with C5Me5H in refluxing ethanol.
Abstract: Paramagnetic ruthenium(III) complex, [(C5Me5)RuCl2]n, is prepared by the reaction of RuCl3·H2O with C5Me5H in refluxing ethanol. Treatment of [Cp*RuCl2]n (Cp* = C5Me5) with cyclic dienes or α,ω-bis(diphenylphosphino)alkanes gives diamagnetic Ru(II) complexes, Cp*RuCl(diene) or Cp*RuCl(dipos), respectively. Cationic diene complex of ruthenium is formed by the reaction of Cp*RuCl(2,5-norbornadiene) with AgBF4.
157 citations
TL;DR: In this article, double-chain alkyl amphiphiles with oligo-L-glutamic acid-head group were prepared and dispersed in water at pH 8 to 9 to form bilayer aggregates.
Abstract: Double-chain alkyl amphiphiles with oligo-L-glutamic acid-head group were prepared. These compounds were dispersed in water at pH 8 to 9 to form bilayer aggregates, in which helical and hollow structures were contained. New CD bands were observed in the solution.
151 citations
TL;DR: In this paper, the nature of two types of oxygen desorption, α and β, from perovskite-type oxides was studied by TPD and TG experiments.
Abstract: The nature of two types of oxygen desorption, α and β, from perovskite-type oxides was studied by TPD and TG experiments. The results show that α oxygen is accomodated in the oxygen vacancies formed by the partial substitution of A site cations, while the desorption of β oxygen corresponds to the reduction of B site cations to lower valencies.
144 citations
TL;DR: In addition to the previously described epoxy fatty acids, five hydroxy fatty acids were characterized as self defensive substances produced in the rice plant against rice blast disease as discussed by the authors, which is a self-defense mechanism for rice plants.
Abstract: In addition to the previously described epoxy fatty acids, five hydroxy fatty acids were characterized as self defensive substances produced in the rice plant against rice blast disease.
125 citations
TL;DR: Borane-dimethyl sulfide complex has proven to be an efficient and selective reducing agent in the presence of catalytic sodium tetrahydroborate for α-hydroxy esters as exemplified in the reduction of dimethyl (S)-(−)-malate, providing the versatile chiral building block of four-carbon backbone as mentioned in this paper.
Abstract: Borane-dimethyl sulfide complex has proven to be an efficient and selective reducing agent in the presence of catalytic sodium tetrahydroborate for α-hydroxy esters as exemplified in the reduction of dimethyl (S)-(−)-malate, providing the versatile chiral building block of four-carbon backbone.
121 citations
TL;DR: In this article, the treatment of 1-unprotected or -O-acetylated sugar derivatives with a hydrogen fluoride-pyridine mixture affords the corresponding 1-fluoro derivatives in high yields.
Abstract: Treatment of 1-unprotected or -O-acetylated sugar derivatives with a hydrogen fluoride–pyridine mixture affords the corresponding 1-fluoro derivatives in high yields.
116 citations
TL;DR: In this article, electron microscopy showed the growth of vesicles of chiral ammonium amphiphiles to helical aggregates and the transformation was determined by the physical state and the chemical structure of the components.
Abstract: Electron microscopy showed the growth of vesicles of chiral ammonium amphiphiles to helical aggregates. The transformation was determined by the physical state and the chemical structure of the components.
105 citations
TL;DR: In this paper, the peculiar variation with x and heat-treatment observed for catalytic activity of CsxH3−xPW12O40 has been explained, based on these results, the authors have shown that Cs2PW 12O40 was precipitated at the Cs/anion ratio of 0.5-2.
Abstract: When H3PW12O40 solution was titrated with Cs2CO3 solution, Cs2PW12O40 was precipitated at the Cs/anion ratio of 0.5–2, while Cs3HPW12O40 was formed at the ratio of 3. Based on these results, the peculiar variation with x and heat-treatment observed for catalytic activity of CsxH3−xPW12O40 has been explained.
82 citations
TL;DR: In this paper, the niobic acid catalysts were more effective than cation exchange resin, SiO2-Al2O3, HZSM-5, and solid super acids such as ZrO2 −SO42−, TiO2−SO42 −, and Fe2O 3−S42−.
Abstract: The niobic acids calcined at moderate temperatures of 120–300 °C showed high catalytic activities (52–75% conv. in 1 h) and selectivities (100%) for the esterification at reaction temperatures of 120–160 °C. No catalyst deactivation was observed even after the use for 60 h. The niobic acid catalysts were more effective than cation exchange resin, SiO2–Al2O3, HZSM-5, and solid super acids such as ZrO2–SO42−, TiO2–SO42−, and Fe2O3–SO42−.
TL;DR: The reaction of 1,2-dienes, phenyl iodide or alkenyl bromides, and secondary amines in the presence of a palladium-phosphine catalyst affords 2-phenyl amines as discussed by the authors.
Abstract: Reaction of 1,2-dienes, phenyl iodide or alkenyl bromides, and secondary amines in the presence of palladium-phosphine catalyst affords 2-phenyl or alkenyl allylic amines.
TL;DR: Various (β-lactams are prepared from the corresponding β-amino acids under mild reaction conditions in high yields by employing 2-chloro-1-methylpyridinium iodide as a condensing reagent.
Abstract: Various (β-lactams are prepared from the corresponding β-amino acids under mild reaction conditions in high yields by employing 2-chloro-1-methylpyridinium iodide as a condensing reagent.
TL;DR: Vapor phase carbonylation of methanol was catalyzed by strong solid acids in the absence of halogen promoter under pressurized conditions in this paper, where methyl acetate, methyl formate and acetic acid were obtained as carbonylated product with dimethyl ether as main by product.
Abstract: Vapor phase carbonylation of methanol was catalyzed by strong solid acids in the absence of halogen promoter under pressurized conditions. Methyl acetate, methyl formate and acetic acid were obtained as carbonylated product with dimethyl ether as main by product. Hydrocarbons were also formed at high temperature.
TL;DR: In this article, terminal allylic compounds such as allylic esters, phenyl ethers, carbonates, chlorides, and vinyl epoxides react with ammonium or sodium formate to give 1-olefins with high regioselectivity by using palladium-tributylphosphine complex as a catalyst.
Abstract: Various terminal allylic compounds such as allylic esters, phenyl ethers, carbonates, chlorides, and vinyl epoxides react with ammonium or sodium formate to give 1-olefins with high regioselectivity by using palladium–tributylphosphine complex as a catalyst. The reaction offers a useful synthetic method for 1-olefins.
TL;DR: Oligoadenylic acids containing 2′-5′ phosphoramide linkage were prepared by poly (U) template-directed condensation as discussed by the authors, and their properties were described.
Abstract: Oligoadenylic acids containing 2′-5′ phosphoramide linkage were prepared by poly (U) template-directed condensation. Some of their properties are described.
TL;DR: In this article, Anthracene-1- or 2-sulfonic and 2-carboxylic acids were found to form one host-two guest inclusion complexes with γ-cyclodextrin in aqueous solutions.
Abstract: Anthracene-1- or 2-sulfonic and 2-carboxylic acids were found to form one host-two guest inclusion complexes with γ-cyclodextrin in aqueous solutions. The complex formation greatly enhanced the pho...
TL;DR: The sex pheromone of grape borer, Xylotrechus pyrrhoderus Bates, was isolated from body extracts and container washings of male insects, and was determined to be a mixture of ( 2S,3S)-octanediol and (2S)-hydroxy-3-octanone.
Abstract: The sex pheromone of grape borer, Xylotrechus pyrrhoderus Bates, was isolated from body extracts and container washings of male insects, and was determined to be a mixture of (2S,3S)-octanediol (1) and (2S)-hydroxy-3-octanone (2). Each compound showed special response in electroantennogram experiments. The females were attracted by 80:20 to 95:5 mixtures of 1 and 2. This is the first time that the male sex pheromone from Cerambycidae species has been isolated and determined.
TL;DR: In the presence of trityl perchlorate, 1-O-bromoacetyl-β-D-glucose stereoselectively reacts with alcohols to give the corresponding β-ribosides in good yields as mentioned in this paper.
Abstract: In the presence of trityl perchlorate, 1-O-bromoacetyl-β-D-glucose stereoselectively reacts with alcohols to give the corresponding α-glucosides in good yields. The similar reaction of 1-O-acetyl-β-D-ribose affords the corresponding β-ribosides exclusively, while in the presence of molecular sieves 4A and lithium perchlorate, α-ribosides are prepared predominantly in good yields.
TL;DR: In this article, the selectivities of alloy catalysts relative to pure metal catalysts were shifted to higher molecular hydrocarbons, and the activities of TiO2-supported bimetallic catalysts of Fe-Co, Co-Ni and Ni-Fe for CO conversion were greater than those of pure-metal catalysts.
Abstract: The activities of TiO2-supported bimetallic catalysts of Fe–Co, Co–Ni and Ni–Fe for CO conversion were greater than those of pure metal catalysts. The selectivities of alloy catalysts relative to pure metal catalysts were shifted to higher molecular hydrocarbons.
TL;DR: In this article, metal dispersion has a striking influence on the activity and selectivity of Rh/SiO2 for high pressure CO hydrogenation and the turnover frequency of CO conversion does not change significantly with dispersion up to 0.5 but increases abruptly at dispersion of 0.45.
Abstract: Metal dispersion has a striking influence on the activity and selectivity of Rh/SiO2 for high pressure CO hydrogenation. Decreasing dispersion, turnover frequency of CO conversion does not change significantly with dispersion up to 0.5 but increases abruptly at dispersion of 0.45. CH3OH is produced selectively at high dispersion. C2-oxygenated compounds are produced favorably for dispersion of 0.25–0.45. CH4 formation increases monotonously with decrease of dispersion.
TL;DR: Water-insoluble polyion complexes were prepared by mixing aqueous solutions of ammonium bilayer membranes and anionic polymers as mentioned in this paper, which retained typical bilayer characteristics and gave transparent films by casting.
Abstract: Water-insoluble polyion complexes were prepared by mixing aqueous solutions of ammonium bilayer membranes and anionic polymers The complexes retained typical bilayer characteristics and gave transparent films by casting
TL;DR: In this article, high resolution MAS 11B-NMR was used to detect quantitatively variously coordinated BOx structural units in zeolites and Boron stemming from Pyrex autoclaves was progressively incorporated into the NMR.
Abstract: High resolution solid state MAS 11B-NMR was used to detect quantitatively variously coordinated BOx structural units in zeolites. Boron stemming from Pyrex autoclaves is progressively incorporated ...
TL;DR: The title compounds, readily prepared from (trimethylsilylmethyl)amines, formaldehyde and an alcohol, react with electron deficient alkenes in the presence of iodosilane or silyl triflate in combination with cesium fluoride to give the corresponding pyrrolidine derivatives stereospecifically in excellent yield as discussed by the authors.
Abstract: The title compounds, readily prepared from (trimethylsilylmethyl)amines, formaldehyde and an alcohol, react with electron deficient alkenes in the presence of iodosilane or silyl triflate in combination with cesium fluoride to give the corresponding pyrrolidine derivatives stereospecifically in excellent yield.
TL;DR: In the presence of a catalytic amount of trityl perchlorate, silyl enol ethers and ketene Silyl acetals react with acetals and methyl orthoformate to give the corresponding aldol-type addition products in good yields as discussed by the authors.
Abstract: In the presence of a catalytic amount of trityl perchlorate, silyl enol ethers and ketene silyl acetals react with acetals and methyl orthoformate to give the corresponding aldol-type addition products in good yields.
TL;DR: Highly oriented polyacetylene was synthesized using nematic liquid crystals as polymerization solvent as discussed by the authors, which was shown to work well for high-dimensional polyethylene applications.
Abstract: Highly oriented polyacetylene was synthesized using nematic liquid crystals as polymerization solvent
TL;DR: In this article, β-Cyclodextrin(β-CD) was found to form inclusion complexes in ethylene glycol, diethane glycol and triethylene glycol.
Abstract: β-Cyclodextrin(β-CD) was found to form inclusion complexes in ethylene glycol, diethylene glycol, triethylene glycol, 2-methoxyethanol, 2-ethoxyethanol, methanol, and glycerine solutions. γ-CD also formed complexes in ethylene glycol solution. The binding of ferrocene by β-CD is stronger in ethylene glycol than in dimethyl sulfoxide and dimethyl formamide.
TL;DR: Sterically protected thermally stable 1,2,3-selenadiphosphirane and diselenoxophosphorane were isolated from the reaction of E-bis-(2,4,6-tri-t-butylphenyl) diphosphene with elemental selenium.
Abstract: Sterically protected thermally stable 1,2,3-selenadiphosphirane and diselenoxophosphorane were isolated from the reaction of E-bis-(2,4,6-tri-t-butylphenyl) diphosphene with elemental selenium
TL;DR: In this article, the reaction of protection-free a-amino acids with aldehydes or ketones in the presence of sodium cyanoborohydride has been shown to yield N-monoalkylated amino acids in inorganic salt-free form.
Abstract: Reactions of protection-free a-amino acids with aldehydes or ketones in the presence of sodium cyanoborohydride afforded the N-monoalkylated amino acids in inorganic salt-free form. Application of this method to the synthesis of N-alkyl derivatives of biologically important amino acids is also described.
TL;DR: In this article, two new C-3/C-3″-biflavanones, neochamaejasmin A and B have been isolated from Stellera chamaejame L. (Thymelaeaceae) and their structures have been elucidated on the basis of spectral data.
Abstract: Two new C-3/C-3″-biflavanones, neochamaejasmin A and B have been isolated from Stellera chamaejasme L. (Thymelaeaceae) and their structures have been elucidated on the basis of spectral data and so...