Studies of poly-yne polymers containing transition metals in the main chain : VI. Synthesis of nickel-poly-yne polymers by alkynyl ligand exchange using a copper(I) catalyst.

Reactions of trans-bis(Tri-n-butlphosphine)diethynylnickel(Ia) with 1-alkynes in the presence of an amine complex of a copper(I) salt as a catalyst give quantitatively alkynyl ligand exchange products. By this method, complex(Ia) reacts with appropriate α,ω-diethynyl compounds to afford high molecular weight linear polymers in good yields. This procedure provides a convenient route to such nickel-poly-yne polymers.     

Synthesis of SMP-797: a new potent ACAT inhibitor

A potent ACAT (acyl-CoA: cholesterol acyltransferase) inhibitor SMP-797 was effectively synthesized by the urea formation of 3-amino-4-aryl-1,8-naphthyridin-2(1H)-one and 4-amino-2,6-diisopropylamine. The synthesis of the former compound involved the Suzuki coupling reaction as a key step, and the latter was prepared by the 4-selective nitration of 2,6-diisopropylaniline using 2,3,5,6-tetrabromo-4-methyl-4-nitro-2,5-cyclohexadienone.     

Accurate mass determination by multiple sprayers nano-electrospray mass spectrometry on a magnetic sector instrument

A new technique for accurate mass determination by using multiple sprayers nano-electrospray ionization mass spectrometry (nano-ESI-MS) on a magnetic sector instrument is described. Metal coated glass capillaries were used as nano-ESI sprayers. One of the sprayers was used for the reference compound solution, and others were used for the introduction of sample solutions. The spectra of the different compounds were obtained by shifting each sprayer's position relative to the sampling orifice. The accurate masses of several standard compounds were obtained with good accuracy, without problems arising from differences in ionization efficiency between the sample compounds and reference compound.     

Coulometric titration of iron by electrolytically generated bromine

Iron^II reacts with bromine more smoothly in acetic acid-sodium acetate medium than in sulphuric acid medium, producing a marked potential change at the end-point. The titration curves and the reaction velocities of the reaction have been studied with regard to various compositions of the electrolytic solution. It was found that iron^IIfrom 0.01 meq to 0.1 meq could be titrated coulometrically with less than about 1% error, if the electrolytic solution contained 0.1M potassium bromate, 1N acetic acid and 0.2N sodium hydroxide.     

Hydrogen atom abstraction and electron transfer of triplet 2,3-dihalo-1,4-naphthoquinones studied by the cidep technique and laser flash photolysis

Investigations using CIDEP techniques showed that an H-atom abstraction from phenol and the electron transfer from 1,2,4,5-tetramethoxybenzene to photoexcited 2,3-dibromo-1,4-naphthoquinone (DBNQ) and 2,3-dichloro-1,4-naphthoquinone (DCNQ) in the polar media originated from their triplet states. Nanosecond laser photolysis at 355 nm was carried out to determine the absorption spectra and coefficients of the corresponding triplet states, semiquinone, and anion radicals for a quantitative investigation of the mechanisms involved in the H-atom abstraction and the electron transfer. The steric hindrance of the substituted groups was indifferent to H-atom abstraction. The electronic structures of triplet DBNQ and DCNQ at 295 K were both revealed to be the mixed states of ³(n,π^*) with a ³(π,π^*) character.     

Hydrolysis and polycondensation of acid-catalyzed Phenyltriethoxysilane (PhTES)

The effects of acid catalyst, water content and reaction temperature on the hydrolysis and polycondensation of phenyltriethoxysilane (PhTES) were studied using ²⁹Si NMR spectroscopy. The sol catalyzed by hydrochloric acid showed the simultaneous progress of hydrolysis and polycondensation. In addition, the reaction rate was almost independent of reaction temperature. On the other hand, the polycondensation in the PhTES-derived sol mixed with an excess amount of water and acetic acid as a catalyst proceeded after completion of the hydrolysis. In the acetic acid-catalyzed system, the degree of the hydrolysis and polycondensation largely depends on the reaction temperature.     

One step synthesis of aziridines by the Michael type addition of free sulfimides: Preparation and absolute configuration of optically active acylaziridines

The Michael type additions of diphenyl N-unsubstituted sulfimide (free sulfimide) to various electrophilic olefins were carried out. The reaction with cis- and trans-dibenzoylethylene, dimethyl-fumarate, dimethylmaleate, benzalacetophenone and benzalacetone gave mainly the corresponding trans-2-acylaziridines and trans-enaminoketones. However, phenyl vinyl sulfone or acrylonitrile afforded not the corresponding aziridine but diphenyl-N-2-cyano or N-2-phenylsulfonylethylsulfimide, a simple Michael adduct When optically active (+)-(R)-o-methoxyphenyiphenyl free sulfimide was treated with such an α,β-unsaturated carbonyl compound as benzalacetopbenone, an optically active 2-acylazindine, i.e., (-)-trans-2-benzoyl-3-phenylaziridine was obtained in ca 30% optical purity and its absolute configuration was assigned as (2R,3S) upon chemical transformation to the configuration-ally known 2-phenyl-2-benzoylamino-1-ethanol or by comparing its CD spectrum with that of (1R,2R)-1-phenyl-2-benzoyl-cyclopropane. Meanwhile, (-)-(S)-o-methoxyphenylphenyl free sulfimide was found to react with benzalacetophenone to afford (+)-trans-2-benzoyl-3-phenylaziridine of 25% optical purity. Effects of solvent and temperature on both die distribution of the products ratio and the optical yield were examined.     

Facile synthesis of acetylenecarboxylates by the oxidative carbonylation of terminal acetylenes catalyzed by PdCl2 under mild conditions

Terminal acetylenes were converted to acetylenecarboxylates in high yields under atmospheric pressure of carbon monoxide at room temperature using a catalytic amount of PdCl₂ and a stoichiometric amount of CuCl₂.     

Bromination of methyl substituted 1,2,5-thiadiazoles with N-bromosuccinimide

Bromomethyl-1,2,5-thiadiazoles 2a-c were prepared by bromination of methyl-1,2,5-thiadiazoles 1a-c by NBS in refluxing carbon tetrachloride. When bromination of 1a and 1b was carried out under irradiation of tungusten lamp, mixtures of cis -5a and b and trans-1,2-dibromo-1,2-bis(1,2,5-thiadiazol-3-yl)ethylene ( 6a and b ) were obtained.