Studies on the syntheses of heterocyclic compounds. Part DCXXXII. The formation of the benzimidazo[2,1-a]isoquinoline by reaction of the 1,2,3,4-tetrahydro-1-(2-nitrophenethyl)isoquinoline with triethyl phosphite

Reductive cyclization of 1,2,3,4-tetrahydro-6,7-dimethoxy-1-(4,5-dimethoxy-2-nitrophen-ethyl)isoquinoline (V) with triethyl phosphite gave 5,6-dihydro-2,3,9,10-tetramethoxybenzimidazo[2,1-a]isoquinoline (IX), whose structure was identified by the spectroscopic analyses by an alternative synthesis.     

Application of palladium catalyses to a simple synthesis of (±)-pyrethrolone

By sequential application of three palladium catalyzed reactions, namely, palladium catalyzed telomerization of butadiene with phenol, oxidation of terminal olefin of the telomer to methyl ketone, and palladium catalyzed elimination of phenol, an E and Z mixture of 5,7-octadien-2-one was prepared in a high yield. This compound was converted to an E and Z mixture of pyrethrolone. The Z form of pyrethrolone was separated from the E isomer by selective adduct formation of the latter with tetracyanoethylene.     

Photochemical dimerization of p-benzoquinone methyl derivatives in crystals

Photochemical dimerization of p-benzoquinone and its methyl derivatives in crystals is discussed assuming that the reactivity is parallel with the stabilization energy of the transient complex. The calculation is carried out by taking both the terms of electronic structure of the monomer molecule and the intermolecular arrangement in the monomer crystal into consideration. Concerning the ability of photodimerization, the result obtained is qualitatively satisfactory. However, such an agreement with experiment cannot be obtained if either the electronic term or the geometrical term is ignored.

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Zusammenfassung Die photochemische Dimerisierung von p-Benzochinon und seines Methylderivates im Kristallzustand wird diskutiert; dabei wird angenommen, daß die Reaktivität parallel zur Stabilisierungsenergie des Übergangskomplexes ist. Die Berechnung wird so durchgeführt, daß sowohl die Elektronenstruktur des monomeren Moleküls als auch die Lage der Moleküle im Kristall des Monomeren berücksichtigt wird. Die Ergebnisse bezüglich der Fähigkeit zur Photodimerisierung sind qualitativ zufriedenstellend. Eine derartige Übereinstimmung mit dem Experiment kann jedoch nicht erhalten werden, wenn entweder der elektronische Beitrag oder der geometrische Beitrag vernachlässigt werden.

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Résumé La dimérisation photochimique de la p-benzoquinone et de ses dérivés méthylés dans les cristaux est discutée en supposant que la réactivité évolue parallèlement à l'énergie de stabilisation du complexe de transition. Le calcul est effectué en tenant compte de la structure électronique du monomère et de l'arrangement intermoléculaire dans le cristal du monomère. Le résultat obtenu est satisfaisant qualitativement en ce qui concerne la facilité de photodimérisation. Cependant, un tel accord avec l'expérience ne pourrait être obtenu si l'un des deux termes électronique ou géométrique était négligé.

     

Catalytic Effects of Metal-loaded Membrane-like Alumina Tubes on Ammonia Synthesis in Atmospheric Pressure Plasma by Dielectric Barrier Discharge

Plasma synthesis of ammonia was studied at atmospheric pressure using a dielectric-barrier-discharge-plasma reactor equipped with a metal-loaded membrane-like alumina tube as a catalyst between the electrodes. Introducing the pure alumina into N₂–H₂ plasma resulted in an increase in the ammonia yield and the further improvement was achieved by loading the alumina with Ru, Pt, Ni, and Fe. These results clearly demonstrate the catalytic effects of the alumina and the metals in the plasma reaction. Temperature-programmed desorption and isotope exchange reaction of nitrogen revealed that plasma-excited N₂ molecules were subjected to dissociative adsorptions mainly on the alumina to form atomic N(a) (The suffix “(a)” denotes adsorbed species) species, which were converted into ammonia by H₂ plasma. A role of the metals is considered to be acceleration of ammonia formation by the reaction of the alumina-adsorbed N(a) atoms with plasma-activated hydrogen species.     

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.     

Synthesis of azoxybenzene-SbCl5 complexes and their selective ortho-wallach rearrangement

When an equimolar solution of various azoxybenzenes and SbCl₅ in carbon tetrachloride were mixed, a 1:1 complex immediately deposited as orange crystals in high yield. The thermal reaction of these complexes in inert solvents gives o-hydroxy-azobenzene selectively. On the contrary, other Lewis acids such as TiCl₄, AlCl₃, FeCl₃ and ZnBr₂ failed to give an isolatable complex with azoxybenzene, and their direct thermal reaction with azoxybenzene resulted in deoxygenation to yield azobenzene as a main product.     

Simultaneous measurements of K+ and calcein release from liposomes and the determination of pore size formed in a membrane.

The changes induced by biologically active substances in the permeability to K+ and calcein of liposomes composed of egg phosphatidylcholine and cholesterol were measured simultaneously in order to rapidly screen the sizes of pores formed in a membrane, using different sized markers. The substances examined in the present study were classified into three types based on differences in the rates at which K+ and calcein were released. The first type released only K+, and included gramicidin A. The second type predominantly released K+, preceding the release of calcein, and included amphotericin B and nystatin. The third type, including antimicrobial peptides, such as gramicidin S, alamethicin, and melittin, and several membrane-active drugs, like celecoxib (non-steroidal anti-inflammatory drug), 1-dodecylazacycloheptan-2-one (named azone; skin permeation enhancer), and chlorpromazine (tranquilizer), caused the release of K+ and calcein simultaneously. Thus, the sizes of pores formed in a liposomal membrane increased in the following order: types one, two, and three. We determined the size more precisely by conducting an osmotic protection experiment, measuring the release of calcein in the presence of osmotic protectants of different sizes. The radii of pores formed by the second type, amphotericin B and nystatin, were 0.36 - 0.46 nm, while the radii of pores formed by the third type were much larger, 0.63 - 0.67 nm or more. The permeability changes induced by substances of the third type are discussed in connection with a transient pore formed in a lipid packing mismatch taking place during the phase transition of dipalmitoylphosphatidylcholine liposomes.