Showing papers in "Chemistry Letters in 1975"
TL;DR: In this article, a continuous silicon carbide fiber of high-tensile strength (about 350 Kg/mm2) was synthesized by means of the heat-treatment of organosilicon polymer obtained from dodecamethylcyclohexasilane.
Abstract: Continuous silicon carbide fiber of high-tensile strength (about 350 Kg/mm2) was synthesized by means of the heat-treatment of organosilicon polymer obtained from dodecamethylcyclohexasilane. X-ray analysis and high voltage electron microscopic observations revealed that the obtained continuous fiber is an ultrafine grain structure of β-silicon carbide.
437 citations
TL;DR: In this article, N-tosylimino-aryl-iodinane was proposed to decompose the I-N ylide and the nitrene intermediate was formed and react with nucleophiles to afford the imine compounds.
Abstract: (Diacetoxyiodo)arene reacts with p-toluenesulfonamide in the presence of base to give the new type I–N ylide, N-tosyliminoaryliodinane. In the decomposition of this ylide, the nitrene intermediate is proposed to be formed and react with nucleophiles to afford the imine compounds.
218 citations
TL;DR: In this article, the equimolar reactions of carboxylic acids and alcohols with 1-methyl-2-halopyridinium salts in the presence of two equalimolar amounts of tri-n-butylamine have been studied.
Abstract: The equimolar reactions of carboxylic acids and alcohols with 1-methyl-2-halopyridinium salts in the presence of two equimolar amounts of tri-n-butylamine afforded the corresponding carboxylic esters in good yields.
158 citations
TL;DR: Watasenia scintillans pyrazin-3-one was discovered from the squid, and its structure was determined by synthesis in this article, which is considered to be a precursor of the unknown Watasenias luciferin or photoprotein.
Abstract: 2-(p-Hydroxybenzyl)-6-(p-hydroxyphenyl)-3,7-dihydroimidazo[1,2-a]pyrazin-3-one was isolated from the squid, Watasenia scintillans. Its structure was determined by synthesis. It is considered to be a precursor of hitherto unknown Watasenia luciferin or photoprotein.
115 citations
TL;DR: The starting material of a continuous silicon carbide fiber with very high tensile strength is a polycarbosilane as discussed by the authors, which decomposes from 300°C in vacuum and is gradually converted into a β-silicon carbide fibre by the heat-treatment at the temperature above 800°C.
Abstract: The starting material of a continuous silicon carbide fiber with very high tensile strength is a polycarbosilane. It begins to decompose from 300°C in vacuum and is gradually converted into a β-silicon carbide fiber by the heat-treatment at the temperature above 800°C.
100 citations
TL;DR: Carboxamides are rapidly formed in high yields by equimolar reactions of free carboxylic acids and amines, involving secondary or tertiary alkyl substituted acids as mentioned in this paper, with 1-methyl-2-halopyridinium iodides in the presence of tri-nbutylamine.
Abstract: Carboxamides are rapidly formed in high yields by equimolar reactions of free carboxylic acids and amines, involving secondary or tertiary alkyl substituted acids and amines, with 1-methyl-2-halopyridinium iodides in the presence of tri-n-butylamine.
100 citations
TL;DR: The long straight line oligomer complexes (1) and (2) composed of metal atoms of the platinum group and conjugated poly-yne systems, and the shorter chain members of the series, (3)∼(6), were prepared and their UV spectra were studied as discussed by the authors.
Abstract: The long straight-line oligomer complexes (1) and (2), composed of metal atoms of the platinum group and conjugated poly-yne systems, and the shorter chain members of the series, (3)∼(6), were prepared and their UV spectra were studied.
87 citations
TL;DR: In this article, it was shown that in the presence of TiCl4, 1-trimethylsiloxy-1,3-butadiene (II) reacts with acetals(I) to give δ-alkoxy-δ,β-unsaturated aldehydes in good yields.
Abstract: ZIt was found that, in the presence of TiCl4,1-trimethylsiloxy-1,3-butadiene (II) reacts with acetals(I) to give δ-alkoxy-δ,β-unsaturated aldehydes in good yields. This reaction provides a novel method for the introduction of–CH2–CH=CH-CHO unit to an electrophile as acetal activated by TiCl4.
70 citations
TL;DR: In this article, the catalytic activity of metal chloride was correlated to the electron affinity of metal cation with two straight lines, and a series of metal chlorides supported on activated carbon was carried out at 200°C.
Abstract: The hydrochlorination of acetylene over a series of metal chlorides supported on activated carbon was carried out at 200°C. The catalytic activity of metal chloride was correlated to the electron affinity of metal cation with two straight lines.
68 citations
TL;DR: In this article, a retracing species in the catalytic reaction path was used to retrace the path of the iodobenzene-potassium cyanide reaction in the presence of a catalytic amount of tetrakis(triphenylphosphine)palladium(O).
Abstract: Cyanogenation of iodobenzene with potassium cyanide has been found to proceed smoothly in tetrahydrofuran in the presence of a catalytic amount of tetrakis(triphenylphosphine)palladium(O). The reaction involves an intermediate, iodo(phenyl)bis(triphenylphosphine)palladium(II), which acts as a retracing species in the catalytic reaction path.
67 citations
TL;DR: In this article, metal-coated semiconductor electrodes have been found to cause photocurrents in aqueous solutions without dissolution into or reaction with the solution, and will be useful as solar-energy convertors.
Abstract: Contrary to most ordinary semiconductor electrodes, metal-coated semiconductor electrodes have been found to cause photocurrents in aqueous solutions without dissolution into or reaction with the solution, and will be useful as solar-energy convertors.
TL;DR: In this article, an oxidative addition of 4,4,6-trimethyl-1,3,2-dioxaborinane and benzo[1, 3, 2]-dorioxaborole to (Ph3P)3RhX, where X= Cl or Br, gives σ-metalloborne which reacts with triethylsilane to afford quantitatively Et3SiRhHX(PPh3)2.
Abstract: Oxidative addition of 4,4,6-trimethyl-1,3,2-dioxaborinane and benzo[1,3,2]dioxaborole to (Ph3P)3RhX, where X= Cl or Br, gives σ-metalloborne which reacts with triethylsilane to afford quantitatively Et3SiRhHX(PPh3)2.
TL;DR: In the presence of a palladium complex, 1,1-dimethyl-1-silacyclobutane reacts smoothly with dimethyl acetylenedicarboxylate to give 1, 1-dimmethyl-2,3-bis(methoxycarbonyl)-1-silacyclohex-2-ene in quantitative yield.
Abstract: In the presence of a palladium complex, 1,1-dimethyl-1-silacyclobutane reacts smoothly with dimethyl acetylenedicarboxylate to give 1,1-dimethyl-2,3-bis(methoxycarbonyl)-1-silacyclohex-2-ene in quantitative yield. Other silacyclobutanes react similarly with various acetylenes to give silacyclohexene derivatives.
TL;DR: In the presence of TiCl4, ketene alkyl trialkylsilyl acetals as discussed by the authors react with aldehydes and ketones at −78°C to afford corresponding β-hydroxyesters and β-trialkylsiloxyesters in good yields.
Abstract: In the presence of TiCl4, ketene alkyl trialkylsilyl acetals, prepared from α-lithio esters and a trialkylsilyl halide, react with aldehydes and ketones at −78°C to afford the corresponding β-hydroxyesters and β-trialkylsiloxyesters in good yields.
TL;DR: A nematicidal component, present at least at 35 ppm, was identified from the roots of asparagus and identified as a poison known as Asparagusic acid, which has also been reported to exist in the edible part of the plant.
Abstract: A nematicidal constituent, present at least at 35 ppm, was isolated from the roots of asparagus and identified as asparagusic acid, which has also been reported to exist in the edible part of the plant. The acid was toxic to several plant parasitic nematodes and would be a major factor in resistance of asparagus.
TL;DR: In this article, aryl Grignard reagents were used to synthesize symmetric atropisomers with a chiral phosphine-nickel catalysts as catalysts.
Abstract: Sterically hindered, unsymmetrical biaryls can be prepared by the cross-coupling reaction of ortho-substituted aryl Grignard reagents with aryl halides in the presence of nickel–phosphine complexes as catalysts. Asymmetric synthesis of biaryl atropisomers has been accomplished with a chiral phosphine-nickel catalyst.
TL;DR: Trimethylsilyl cyanide was found to react with Schiff bases and oximes in the presence of a catalytic amount of Lewis acids to afford N-trimmethylsilylsilyl-α-aminonitriles and Ntrimethyl silyloxy-α -amin....
Abstract: Trimethylsilyl cyanide was found to react with Schiff bases and oximes in the presence of a catalytic amount of Lewis acids to afford N-trimethylsilyl-α-aminonitriles and N-trimethylsilyloxy-α-amin...
TL;DR: The reaction of 2,6-dibromocyclohexanone (1) with morpholine gives 1-cyclopentenecarboxymorpholide (2) and 2-morpholino-2-cyclohexenone (3) as discussed by the authors.
Abstract: The reaction of 2,6-dibromocyclohexanone (1)with morpholine gives 1-cyclopentenecarboxymorpholide (2) and 2-morpholino-2-cyclohexenone (3) . The ratio of 2 :3 is remarkably affected by the reaction solvent, and the amide 2 or the enaminoketone 3 is obtained selectively when chloroform or HMPA was used, respectively.
TL;DR: In this article, a new synthesis of vitamin A was successfully accomplished by reducing retinal, prepared by the reaction of 3-methyl-1-trimethylsiloxy-1,3-butadiene (III) with β-ionylideneacetaldehyde dimethyl acetal (VII) followed by the elimination of methanol with tertiary amine such as 1,5-diazabicyclo[5.4.0]undecene-5.
Abstract: A new synthesis of vitamin A was successfully accomplished by reducing retinal, prepared by the reaction of 3-methyl-1-trimethylsiloxy-1,3-butadiene (III) with β-ionylideneacetaldehyde dimethyl acetal (VII) followed by the elimination of methanol with tertiary amine such as 1,5-diazabicyclo[5.4.0]undecene-5. The intermediate, β-ionylideneacetaldehyde (V), was also prepared according to the same procedure starting from β-cyclocitral dimethyl acetal (II).
TL;DR: In this article, a catalytic reduction of aromatic nitro compounds to aromatic amino compounds with hydrazine in the presence of Fe(III) chloride and active carbon was studied, and the corresponding amino compounds were obtained with excellent purities and in good yields.
Abstract: A catalytic reduction of aromatic nitro compounds to aromatic amino compounds with hydrazine in the presence of Fe(III) chloride and active carbon was studied. The corresponding amino compounds were obtained with excellent purities and in good yields. The method was also applied to the partial reduction of dinitro compounds.
TL;DR: Several new halogenate monoterpenes have been isolated from Hawaiian Chondrococcus hornemanni which suggest that the halogenated myrcenes are formed by the enzymatic addition of BrCl followed by dehydrohalogenation.
Abstract: Several new halogenated monoterpenes (3–6,10–15) have been isolated from Hawaiian Chondrococcus hornemanni which suggest that the halogenated myrcenes are formed by the enzymatic addition of BrCl followed by dehydrohalogenation.
TL;DR: In this article, a quantitative yield of the oxidative dimer with 100% current efficiency was achieved by using enolate enolate of ethyl phenylacetate with no activating groups at low temperature.
Abstract: Electrochemical oxidation of lithium enolates of esters containing no activating groups at low temperature produced the corresponding substituted succinate esters in fairly good yields Electrolysis of enolate of ethyl phenylacetate also produced a quantitative yield of the oxidative dimer with 100% current efficiency.
TL;DR: In this article, the aromatic compounds, which have both hydroxymethyl and methoxyl groups at 1,3-position, were lithiated mostly at 2-position with n-butyllithium.
Abstract: The aromatic compounds, which have both hydroxymethyl and methoxyl groups at 1,3-position, were lithiated mostly at 2-position with n-butyllithium. This reaction would provide a useful synthetic method of methoxyphthalide derivatives, in conjunction with carboxylation of the resulting lithio-compounds.
TL;DR: The cathodic polarization characteristics of lanthanum nickel oxide, LaNiO3, were investigated in O2-saturated alkaline solutions and it was found that this oxide has a high catalytic activity for oxygen reduction.
Abstract: The cathodic polarization characteristics of lanthanum nickel oxide, LaNiO3, were investigated in O2-saturated alkaline solutions and it was found that this oxide has a high catalytic activity for oxygen reduction. This paper represents the results in brief.
TL;DR: In this paper, a 1:2 cycloaddition reaction with butadiene or isoprene in the presence of a palladium complex was proposed for organodisilanes, which gave 1.5,5,8,11,hexamethyl-l,5-disilacyclotrideca-7,11-diene in 76% yield.
Abstract: Organodisilanes undergo a novel 1:2 cycloaddition reaction with butadiene or isoprene in the presence of a palladium complex. For example, the reaction of 1,1,2,2-tetramethy1-1,2-disilacyclopentane with isoprene gave 1,1,5,5,8,11-hexamethyl-l,5-disilacyclotrideca-7,11-diene in 76% yield.
TL;DR: In this article, the TiCl4-promoted addition of diketene to various aldehydes, followed by the treatment with alcohol, was successfully applied to the syntheses of dihydrokawain and kawain.
Abstract: δ-Hydroxy-β-ketoesters[3] and 6-alkyl-5, 6-dihydro–4-hydroxy-2-pyrones[4] were obtained in good yields by TiCl4-promoted addition of diketene[1] to various aldehydes[2], followed by the treatment with alcohol. The hydroxyketoesters[3] were easily lactonized to the corresponding lactones[4] in excellent yields by the hydrolysis with aqueous alkali, followed by acidification. The present method was successfully applied to the syntheses of dihydrokawain[7c] and kawain[7d].
TL;DR: Bis(salicylidene)ethylenediaminatocobalt(II) catalyzes the oxygenation of 3-substituted indoles related to tryptophan in methanol giving rise to oxidative cleavage of the heterocyclic ring of the indoles selectively to give the corresponding o-formylaminoacetophenone derivatives.
Abstract: Bis(salicylidene)ethylenediaminatocobalt(II) catalyzes the oxygenation of 3-substituted indoles related to tryptophan in methanol giving rise to oxidative cleavage of the heterocyclic ring of the indoles selectively to give the corresponding o-formylaminoacetophenone derivatives. This provides a nonenzymic model for the reaction of tryptophan 2,3-dioxygenase. Oxidizability of the substrates is correlated with their donor ability.
TL;DR: In this paper, 1-Methyl-2-alkoxypyridinium salts, easily formed in situ from l-methyl 2-fluoropyrinium salt and alcohols, react with pyrid 2-thione in the presence of triethylamine to give the corresponding 2-pyridyl sulfides in good yields.
Abstract: 1-Methyl-2-alkoxypyridinium salts, easily formed in situ from l-methyl-2-fluoropyridinium salt and alcohols, react with pyrid-2-thione in the presence of triethylamine to give the corresponding 2-pyridyl sulfides in good yields.
TL;DR: The structure of the active principle of Coryne Uchidai was unequivocally confirmed by synthesis and (±)-epoxide exhibited the clear activity toward the settling of swimming larvae.
Abstract: Based on the observation that the juice of yoremoku induces the settling of swimming larvae of Coryne Uchidai, we searched the active component in the alga by means of bioassay using the swimming larvae and elucidated the structure of the active principle to be 1 and 2. The structure was unequivocally confirmed by synthesis and (±)-epoxide (2) exhibited the clear activity toward the settling of swimming larvae.