bluuebunny/crossref_metadata_2025 huggingface dataset:
Adsorption of Hydrophobic Anions onto Phospholipid Membranes. The Effect of Membrane Surface Charge
Authors: Matsumura Hideo , Kakoki Hiroyuki , Furusawa Kunio
Published: July 2006

Hydrophobic adsorption of tetraphenylborate ions (TPB) onto lipid membranes were studied at different pH’s of aqueous phase by using lipid vesicles and monolayers. The amount of adsorbed TPB is much higher at pH 2 than at pH 7.4. This result indicates that the adsorption of hydrophobic ions is affected by the ionization state of surface polar groups of lipids, i.e., that the membrane surface potential plays a role in the adsorption of hydrophobic ions.
Synthesis of Pyrazolo[3,4-d]thiazoles
Authors: Thiruvikraman S V , Seshadri S
Published: July 2006

Several 5-substituted 1-phenylpyrazolo[3,4-d]thiazole derivatives have been synthesized by reaction of 5-amino-3-methyl-1-phenylpyrazole-4-thiol with different reagents.
Synthesis of 4-(1,5,9-Trimethyl-1-vinyl-4,8-decadienyl)catechol Dimethyl Ether
Authors: Anand Ramesh Chander , Ranjan Harish
Published: July 2006

Synthesis of 4-(1,5,9-trimethyl-1-vinyl-4,8-decadienyl)catechol dimethyl ether has been described utilizing Wittig reaction for the introduction of vinylic substituent at the quaternary carbon.
Study of Chemisorption and Hydrogenation of 2-Butenes on Platinum by Temperature-programmed Desorption
Authors: Tokitaka Shinji , Imamura Hayao , Tsuchiya Susumu
Published: July 2006

The temperature-programmed desorption (TPD) chromatograms of cis- and trans-2-butene from platinum black comprised three peaks (A, B, and C) with peak maxima at about 253, 373, and 573 K, respectively. Peak A was identified to be cis- or trans-2-butene and butane. Peaks B and C were from mixtures of cis- or trans-2-butene and butane with a trace amount of propylene. The propylene may have been formed from chemisorbed cis- or trans-2-butene by decomposition as the temperature was raised during the subsequent TPD. The reactivities of various types of chemisorbed hydrogen previously detected by TPD were also investigated with regard to the hydrogenation of 2-butenes. Two types of chemisorbed hydrogen, presumed to be present on the surface in the form of hydrogen atoms, chemisorbed on top of platinum atoms and in the bridge form of molecular hydrogen, were found to react with 2-butenes.
Rearrangement Approaches to Cyclic Skeletons. II. Structural Revision and Total Synthesis of (±)-Isosesquicarene, a [3–6] Fused-Ring Sesquiterpene
Authors: Uyehara Tadao , Yamada Jun-ichi , Kato Tadahiro , Bohlmann Ferdinand
Published: July 2006

The exo-7-(4-methyl-3-pentenyl) derivative of 3-carene (1a), the original structure reported for (±)-isosesquicarene, was synthesized starting from tropone, and it was found that 1a is not identical with natural isosesquicarene. The structure of isosesquicarene was reinterpreted as endo-7-(4-methyl-3-pentenyl) derivative of 3-carene (1b). The first total synthesis of (±)-isosesquicarene, 1b, has been accomplished on the basis of the photochemical transformation of 4-methylbicyclo[3.2.2]nona-3,6-dien-2-one into the 7-exo-methylbicyclo[4.1.0]hept-2-ene.
Preparation of LaNi5 Films and Effects of Hydrogen Absorption on Electrical Resistivities of the Films
Authors: Adachi Gin-ya , Sakaguchi Hiroki , Niki Ken-ichi , Nagai Hiroshi , Shiokawa Jiro
Published: July 2006

Thin films of LaNi5 have been prepared by means of a flash evaporation-deposition technique. Electric resistivity measurements on these films were carried out in an atmosphere of hydrogen. The films formed on quartz substrates were amorphous. Resistivities initially increased and then decreased during the absorption of hydrogen. During the desorption process, the reverse phenomenon was observed. The effect of the thickness of the films on the electric properties, during the hydrogen absorption-desorption process, was also studied. Sample pulverization could be avoidable by using films of less than 10 μm in thickness. The hydrogen contents of the films were determined by the quartz-crystal mass-monitoring (QCMM) method.
Convenient Preparations of 3,5-Disubstituted 1,2,4-Thiadiazoles by Oxidative Dimerization of Thioamides
Authors: Takikawa Yuji , Shimada Kazuaki , Sato Katsuyuki , Sato Shinichi , Takizawa Saburo
Published: July 2006

3,5-Disubstituted 1,2,4-thiadiazoles 2 were prepared by reaction of thioamides 1 with DMSO in the presence of such an electrophilic reagent as 1-methyl-2-chloropyridinium iodide, benzoyl chloride, acetyl chloride, hydrochloric acid, or trimethylsilyl chloride in organic solvents at room temperature in high yields. Thiadiazoles 2 were also obtained by reaction of 1 with NBS at room temperature in high yields. Thioamide S-oxides reacted with electrophilic reagents at room temperature to give the corresponding thiadiazoles 2 in high yields.
Preparation and Stereochemistry of Cobalt(III) Complexes Containing 2,11-Diphenyl-5,8-diaza-2,11-diphosphadodecane or (4S,9S)-4,9-Dimethyl-2,11-diphenyl-5,8-diaza-2,11-diphosphadodecane, (C6H5)(CH3)PCH2CHRNHCH2CH2NHCHRCH2P(CH3)(C6H5) (R=H or CH3)
Authors: Atoh Masamichi , Kashiwabara Kazuo , Fujita Junnosuke
Published: July 2006

New quadridentate ligands having two chiral phosphorus donor atoms, 2,11-diphenyl-5,8-diaza-2,11-diphosphadodecane (mp-PNNP) and (4S,9S)-4,9-dimethyl-2,11-diphenyl-5,8-diaza-2,11-diphosphadodecane (SS(C)-mp-PNNP), and their cobalt(III) complexes, trans-[CoCl2(mp- or SS(C)-mp-PNNP)]+ and cisβ-[Co(acac)(mp- or SS(C)-mp-PNNP)]2+ (acac=2,4-pentanedionate ion) were prepared and characterized. For both mp- and SS(C)-mp-PNNP, the dichloro and acac complexes formed three and four isomers, respectively, which were separated by column chromatography or fractional crystallization. No cisα-acac complex was yielded. The acac complexes of SS(C)-mp-PNNP formed a Λ-isomer stereoselectively. The absolute configurations of the phosphorus donor atoms in the SS(C)-mp-PNNP complexes were assigned on the basis of the 1H NMR and CD spectra. It was shown that the phosphorus donor atoms at chemically unequivalent coordination positions in cisβ-[Co(acac)(SS(C)-mp-PNNP)]2+ give remarkably different vicinal effects on the CD spectra.
Cerium or Ruthenium Catalyzed Oxidation of Alcohols to Carbonyl Compounds by Means of Sodium Bromate
Authors: Kanemoto Shigekazu , Tomioka Hiroki , Oshima Koichiro , Nozaki Hitosi
Published: July 2006

Sodium bromate has been found to be effective oxidant for oxidation of alcohols in the presence of cerium or ruthenium compounds in biphase reaction. Selective oxidation of secondary alcohols was performed in the presence of primary ones using cerium(IV) ammonium nitrate (CAN) or cerium(IV) sulfate (CS) as catalyst. For instance, treatment of 1,10-undecanediol with CS/NaBrO3 provided 11-hydroxy-2-undecanone in 82% yield. Ruthenium catalyzed biphase oxidation of alcohols with sodium bromate provided the corresponding aldehydes or ketones in good to excellent yields.
Quantitative Analysis of Effects of Substituted Phenols on Membrane Characteristics of Lecithin Liposomes
Authors: Miyoshi Hideto , Nishioka Takaaki , Fujita Toshio
Published: July 2006

The partition coefficient of a series of substituted phenols in a lecithin liposome/water system, P(L/W), and the effects of these compounds on the perturbation of liposomal membranes were quantitatively investigated using physicochemical molecular parameters. Partition behavior is primarily governed by hydrophobicity, represented in terms of the 1-octanol/water partition coefficient. Steric and electronic characters also were of significance. Potency in perturbation of liposomal membranes was governed by the degree of partitioning to the membrane and the steric bulkiness of the phenol. This kind of quantitative procedure was very helpful in investigating the effects of organic molecules on membrane characteristics.
Synthetic Photochemistry. XXXIV. Synthetic Strategy of 5-8-5-Membered Tricyclic Higher Terpenoids Based on the Condensation of Two Optically-Active Iridoids, C10-Synthons Obtained from Photo-Cycloadduct of Methyl 2,4-Dioxopentanoate–Isoprene, and Its Application to a Synthesis of the Basic Carbon Skeleton of Fusicoccane
Authors: Kato Nobuo , Nakanishi Kohji , Takeshita Hitoshi
Published: July 2006

One of the photocycloadducts obtained during methyl 2,4-dioxopentanoate to isoprene was converted to optically active iridoids. Using a CrCl2 reductive-coupling reaction, proper combinations of two kinds of enantiomeric iridoids, 1-iriden-7-al and 9-benzyloxy-7-chloro-1-iridene, produced versatile intermediates for various types of 5-8-5-membered tricyclic natural products. From one such product, fusicocca-2,8,10(14)-triene (1) was synthesized by sequential transformations.
Synthesis of 3-Arylmethyl-p-tropoquinones from 5-Alkoxy-2-(arylmethoxy)tropones via Homolytic Rearrangement and Oxidation
Authors: Takeshita Hitoshi , Mori Akira , Goto Yasutomo
Published: July 2006

The 3-(arylmethyl)-p-tropoquinones were synthesized by starting from the homolytic thermal rearrangement of 2-(arylmethoxy)-5-methoxytropones or 2,5-bis(arylmethoxy)tropones, followed by hydrolysis and oxidation. The half-wave potentials of these tropoquinones were determined by cyclic voltammetry. A remote substituent effect was observed for 3-(4-hydroxybenzyl)-p-tropoquinone, which may be attributable to intermolecular hydrogen bonding.
Photochemical Reactions of Aromatic Compounds. XLII. Photosensitized Reactions of Some Selected Diarylcyclobutanes by Aromatic Nitriles and Chloranil. Implications of Charge-Transfer Contributions on Exciplex Reactivities
Authors: Pac Chyongjin , Ohtsuki Tomohito , Shiota Yozo , Yanagida Shozo , Sakurai Hiroshi
Published: July 2006

Photosensitized reactions of cis- and trans-1,2-diphenylcyclobutane and cis-transoid-cis-cyclobuta[1,2-a : 4,3-a′]diindene by 1-cyanonaphthalene, 9,10-dicyanoanthrancene, 1,4-dicyanonaphthalene, and chloranil, which mainly give the ring-splitting product (styrene or indene), have been investigated to explore steric and electronic requirements of the reactions associated with charge-transfer and excitation-resonance contributions of exciplex intermediates. The reaction efficiencies increase with an increase in the electron-accepting power of the sensitizers irrespective of the spin states. The formation of 1-phenyltetralin in the photosensitized reactions of the diphenylcyclobutanes occurs from the polar singlet exciplex with the dicyanoarenes but not at all from the less polar exciplex with 1-cyanonaphthalene nor from the triplet chloranil exciplex of high charge-transfer nature. Exciplex reactivities are discussed in terms of roles of charge-transfer contributions in exciplex decay channels as well as in terms of configurational and conformational effects on orbital interactions in the cyclobutanes.
Molecular Motions in Plastic Phase of 2-Methyl-2-nitropropane, (CH3)3CNO2, by Pressure and Temperature Dependences of 1H-NMR Spin-Lattice Relaxation
Authors: Hasebe Tooru , Chihara Hideaki
Published: July 2006

Proton NMR spin-lattice relaxation time, T1, in the plastic phase of 2-methyl-2-nitropropane (CH3)3CNO2 was measured at 10 MHz up to 150 MPa between 262 and 320 K. The overall molecular reorientation with an activation enthalpy of ΔHr*=6.8±1.0 kJ mol−1 and an activation volume of ΔVr*=(0.07±0.02)Vm did not show significant pressure dependence up to 140 MPa, where Vm is the molar volume of (CH3)3CNO2 at 273.2 K. The self-diffusion, which was treated by the Torrey’s isotropic diffusion model, showed large pressure dependence; the activation enthalpy, ΔHd* changed from 46±4 kJ mol−1 under saturated vapor pressure of the sample to 95±8 kJ mol−1 under 100 MPa and the activation volume, ΔVd* changed from Vm at 278.0 K to 0.8Vm at 320.0 K. These results strongly suggest monovacancy mechanism for self-diffusion. The phase diagram of liquid-plastic and plastic-brittle phase transitions is also given.
Basic Study on Lithium Recovery from Lithium Containing Solution
Authors: Yoshinaga Tetsutaro , Kawano Kentaro , Imoto Hirotsugu
Published: July 2006

Basic study of Li recovery using high purity sodium aluminate solution as coprecipitating agent has been made. Al concentration, pH and temperature greatly affect the Li recovery, and in this study the temperature was maintained constant (25 °C). For reference lithium solution, the optimum (initial) pH obtained increased with an increase in Al concentration. Optimum pH=11.0–12.5 for [Al]=50–1000 mg dm−3. The optimum pH values obtained were lower than those in the previous work by about one pH unit. The following relationship was found between the Al concentration CAl (mg dm−3) and the optimum pH; Opt. pHexp=8.23+1.5log CAl. Furthermore, these experimental pH values were in fair agreement with the pH values calculated from the solubility product of aluminium hydroxide, Ksp (HAlO2)=[H+][AlO2−]=10−13.2, i.e., pHcalcd=9.5+log CAl. Effects of coexistent ions on Li recovery were examined. Sodium and potassium ions did not interfere, while calcium, magnesium, and monosilicate ions did. However, the interference from Ba2+ ions was small. Especially, interference by calcium and monosilicate ions were significant. Bubbling of CO2 gas into the Li solution with proper Al concentration made a remarkable improvement on Li recovery. Accordingly, the influence of water soluble carbonates on Li recovery was investigated. The carbonates (Na2CO3, K2CO3, (NH4)2CO3) used were found to be very effective for Li recovery. The addition of sodium aluminate solution (500 mg dm−3) to untreated geothermal water showed around 70% of Li recovery at the best. This incomplete recovery of lithium is due to the matrix effect of geothermal water. For reference Li solution with Al concentration of 500 mg dm−3, optimum pH was 12.5, while for Ca, SiO2-free geothermal water the same pH gave very low Li recovery. However, when a pH value of 11.5 is chosen, a remarkable increase in Li recovery was obtained (98–99%). The silica component in geothermal water interfered with the Li recovery, but the influence was relatively small. The silica in the geothermal water in this case, was polymerized and showed some buffering action, such as prevention of interference from calcium ions. This is the significant difference between poly and monosilicate ions which do not show any buffering action. The addition of sodium carbonate to the Ca,SiO2-free geothermal water caused a remarkable acceleration of the Li recovery, similar to that for the reference Li solution.
Crystal and Molecular Structure of 3-Pyrazolone Derivatives. III. 5-Amino-2-phenyl-4-(9H-thioxanthen-9-yl)-1,2-dihydro-3H-pyrazol-3-one
Authors: Kimura Michio
Published: July 2006

The crystal and molecular structure of 5-amino-2-phenyl-4-(9H-thioxanthen-9-yl)-1,2-dihydro-3H-pyrazol-3-one has been determined by the X-ray diffraction method to establish the predominant tautomeric form of the 3-pyrazolone ring in the solid state. The title compound, C22H17N3OS, crystallizes in the space group P21⁄c with lattice parameters: a=18.179(4), b=8.333(1), c=11.961(7) Å, β=95.88(3)°, and Z=4. The 5-amino group is intramolecularly hydrogen-bonded to the sulfur atom of the thioxanthene ring (N–H···S=3.284 Å). In the packing structure, molecules are linked to each other through hydrogen bonds between the NH of amino and C=O groups [2.849 Å] and the NH moiety and C=O group [2.939 Å] of the 3-pyrazolone ring.
A Reinterpretation for Ion Association at Micellar Surfaces Due to an Electrostatic Model
Authors: Kaneko Tetsuo
Published: July 2006

Ion association at the surface of a micelle is reinterpreted by considering that counter ions are bound by an electrostatic attraction with a spherical shell which is formed by the aggregation of the polar heads of amphiphilic molecules. It was found that the degree of ion association increased slightly with the increase in the aggregation number of amphiphilic molecules.
A Novel Development for the Simulater of Intermolecular Potentials
Authors: Takagi Tatsuya , Tanaka Akito , Maeda Shigeo , Matsuo Sanshiro , Fujiwara Hideaki , Sasaki Yoshio
Published: July 2006

A novel treatment for the estimation of intermolecular interactions is proposed, incorporating intermolecular parameters into the semiempirical MNDO MO method. These parameters vary depending on the atomic species, but are constants to be reduced to the original MNDO formalism when the atomic pair belongs to a same molecule. The core–core repulsion and the two electron integral terms were modified using these parameters. The parameters introduced have been determined so as to reproduce well the interaction energies of the different model systems of molecular interaction. The resulting parameters permit calculations of large systems with sufficient accuracy within reasonably short CPU time.
Solvent Extraction of Palladium(II) from Aqueous Chloride Media with 1,2-Bis(tert-hexylthio)ethane
Authors: Baba Yoshinari , Eguchi Toshiya , Inoue Katsutoshi
Published: July 2006

The extraction equilibrium and kinetics of palladium(II) extraction from an aqueous chloride media with 1,2-bis(tert-hexylthio)ethane (mixture), abbreviated as t-BHTE and denoted by B, in toluene were studied at 303 K. Palladium(II) was extracted as a 1:1 Pd : extractant complex, [PdCl2B]. The partition coefficient of this extractant was evaluated as Kd=5.5×104 for hydrochloric acid and Kd=2.5×104 for an aqueous ammonium chloride solution. The results of kinetic experiments were quantitatively explained in terms of a reaction scheme in which parallel reactions of t-BHTE with [PdCl3]− and [PdCl4]2− in an aqueous phase were the rate-determining steps:

[PdCl3]−aq.+Baq.\xrightarrowk1[PdCl2B]aq.+Cl−aq.

[PdCl4]2−aq.+Baq.\xrightarrowk2[PdCl2B]aq.+2Cl−aq.

The reaction rate constants for the above were evaluated as k1=6.4×104 dm3 mol−1 s−1 and k2=2.6×102 dm3 mol−1 s−1 for extraction from an aqueous ammonium chloride solution, and k1=6.7×104 dm3 mol−1 s−1 and k2=3.2×102 dm3 mol−1 s−1 from a hydrochloric acid solution.
Versatile Synthesis of Cyclopropanecarboxylic Acid Derivatives by the Ni(CO)4-Induced Reductive Carbonylation Reaction of gem-Dibromocyclopropanes
Authors: Hirao Toshikazu , Harano Yoshiyuki , Yamana Yoshihiro , Hamada Yuji , Nagata Shinichiro , Agawa Toshio
Published: July 2006

Reductive carbonylation of gem-dibromocyclopropanes was achieved by treatment with tetracarbonylnickel in the presence of alcohols, amines, thiols, or imidazole in DMF leading to the corresponding cyclopropanecarboxylic acid derivatives, respectively. Use of disulfides as an initial nucleophile resulted in carbonylation with sulfenylation at the geminal position. This method was applied to the intramolecular reductive carbonylation reaction of 2,2-dibromocyclopropanealkanols into bicyclic lactones. Nickel carbenoid and enolate complexes are assumed to be involved as key intermediates.
Regioselectivity in the Catalytic Hydrogenolysis of 7-Fluoro-1-phenylbicyclo[4.1.0]heptanes
Authors: Isogai Koji , Sakai Jun-ichi , Kosugi Katsuhiko
Published: July 2006

The palladium-catalyzed hydrogenolysis of 7-chloro-7-fluoro-1-phenyl-, 7-fluoro-1-phenyl-, and 7,7-difluoro-1-phenylbicyclo[4.1.0]heptane was investigated. The hydrogenolysis of the cyclopropane ring occurs at the C1–C6 bond selectively, accompanied by the elimination of the endo-halogen. The hydrogenolysis of endo-7-fluoro-1-phenylbicyclo[4.1.0]heptane proceeded rapidly to give phenylcycloheptane as a sole product, whereas exo-7-fluoro-1-phenylbicyclo[4.1.0]heptane reacted slowly to give trans-1-fluoro-2-phenylcycloheptane, accompanied by a small amount of the C1–C7 bond-cleaved product. The different reactivity between the endo and exo derivatives became more considerably by the introduction of a methyl group at the 2-position. Thus, with the compounds having 2-methyl group the endo-fluoro derivative was cleaved at the C1–C6 bond accompanied by the C1–C7 bond cleavage, whereas the exo-fluoro derivative was cleaved at the C1–C7 bond exclusively.
Studies on Glycosylation of erythro-β-Hydroxy-l-histidine. A Key Step of Bleomycin Total Synthesis
Authors: Miyake Toshiaki , Tsuchiya Tsutomu , Umezawa Sumio , Saito Seiichi , Umezawa Hamao
Published: July 2006

To improve the synthetic yield of bleomycin and its analogues, it is necessary to find the high yield procedure for condensation of sugar portion with the hydroxyl group of erythro-β-hydroxy-l-histidine moiety, preventing the N-glycosylation to imidazole. The present studies include the condensations of 4,6-di-O-acetyl-2,3-di-O-methyl-α-d-glucopyranosyl bromide (10) or 3,4,6-tri-O-acetyl-2-O-(2,4,6-tri-O-acetyl-3-O-carbamoyl-α-d-mannopyranosyl)-α-l-gulopyranosyl bromide (3) and 3,4,6-tri-O-acetyl-2-O-[2,4,6-tri-O-acetyl-3-O-(N-acetylcarbamoyl)-α-d-mannopyranosyl]-α-l-gulopyranosyl bromide (28) with a variety of protected derivatives of erythro-β-hydroxy-l-histidine. The results revealed that a) Nim-tosyl group is most effective to prevent the Nim-glycosylation, b) use of silver carbonate and silver perchlorate at low temperature (−55 °C) gave the desired α-glycosides in satisfactory yields, and c) among the esters (methyl and p-nitrobenzyl) and the N-protecting groups (Z, Boc, and pMZ) of erythro-β-hydroxy-l-histidine, methyl and Z were the best groups, respectively. Using the method thus improved, the desired O-α-l-guloside, that is, erythro-β-O-[3,4,6-tri-O-acetyl-2-O-(2,4,6-tri-O-acetyl-3-O-carbamoyl-α-d-mannopyranosyl)-α-l-gulopyranosyl]-Nα-benzyloxycarbonyl-Nim(τ)-tosyl-l-histidine p-nitrobenzyl ester (31) was successfully prepared.
A New Method for Measuring 1:1 Association Constants Based on Releasing Rate of Free Ligand from Aqueous into Gaseous Phase, Applied to Determining Formation Constants of Metal Acetylacetonate Complexes
Authors: Sanemasa Isao , Nishimoto Yuko , Tanaka Akira , Deguchi Toshio
Published: July 2006

A simple method is presented that allows estimation of 1:1 association constants between volatile and nonvolatile solutes in aqueous medium. On introducing an inert gas at a constant flow rate into the aqueous phase, the volatile solute is expelled from the solution, and the amount of the released solute is measured as a function of aeration time. Measurements are made in two separate runs at the same inert gas flow rate, one in the absence and the other in the presence of nonvolatile solutes. The releasing rate of the volatile solute is reduced with increasing association between both the solutes in the aqueous medium. The method was used to estimate formation constants of 1:1 acetylacetone complexes with metal ions, Cu(II), Ni(II), Co(II), Mg(II), Fe(II), Fe(III), and Al(III), at 25.0°C and I=0.1 (NaClO4), results being compared with literature values.
Synthesis of Photosensitive Poly(2,5-Norbornadien-7-yl Acrylate and Methacrylate)
Authors: Kamogawa Hiroyoshi , Yamada Makoto
Published: July 2006

2,5-Norbornadien-7-yl acrylate and methacrylate were synthesized by the esterification of 2,5-norbornadien-7-ol with acryloyl and methacryloyl chlorides, respectively. Polymerization of the monomers with AIBN provided vinyl polymers with pendant norbornadiene units, which could be made to clear films from CH2Cl2. UV-irradiations brought about remarkable changes in the 200 nm region of the absorption spectra of the films, indicating the formation of quadricyclane units. These could be partially converted back by immersion in a cobalt(II) 5,10,15,20-tetraphenylporphyrin solution.
Copper(I), Silver(I), Mercury(II), and Palladium(II) Complexes of Tetrathia[n]ferrocenophanes
Authors: Sato Masaru , Tanaka Shinsuke , Akabori Sadatoshi , Habata Yoichi
Published: July 2006

The complexes of a series of macrocyclic tetrathioether ligands containing a ferrocene nucleus in the macrocycle, tetrathia[n]ferrocenophanes, with copper(I), silver(I), mercury(II), and palladium(II) salts were prepared and characterized. The stability of complexes seems to depend on the size of the macrocycles in tetrathia[n]ferrocenophanes. The interaction between the iron atom of a ferrocene nucleus and the metal ions incorporated in the macrocycles seems to be negligible in these complexes.
Compensation Effect in the Electrical Conduction Process in Some Nucleic Acid Base Complexes with Acriflavine Dye
Authors: Sarkar Deepali , Jain Kapur Mal , Misra Tridibendra Narayan
Published: July 2006

The validity of the compensation rule is studied for nucleic acid bases, adenine, cytosine, and uracil complexes with acriflavine dye. The value of the semiconduction activation energy of a complex varies with dye concentration. It is shown that at low dye concentration, these semiconducting complexes follow the three parameter equation σ(T)=σ′0exp(E⁄2kT0)exp(−E⁄2kT), where σ′0 and T0 are constant for a particular base, other notations have their usual meaning. Consistent values for σ′0 and T0 have been obtained by using various methods of evaluation. These results suggest that compensation effect has a physical origin.
Determination of Iron in Drug Biochemical and Biological Samples as a Thiocyanato Mixed Ligand Complex with Hydroxyamidine
Authors: Singh Raghunandan , Chandrakar Lalta Prasad , Mishra Rajendra Kumar
Published: July 2006

N-Hydroxy-N-o-tolyl-N′-phenylbenzamidine (HTPB) is presented as a new sensitive and highly selective reagent for determination of iron in drug, biochemical and biological samples in presence of thiocyanate. The red organge Fe(III)–HTPB–SCN mixed ligand complex is quantitatively extracted into benzene. The extraction of iron(III) as thiocyanato mixed ligand complex is quantitative in the acidity range between 0.2–0.7 M (1M=1 mol dm−3) hydrochloric acid. The effective molar absorptivity of the complex is 12000 l mol−1 cm−1 with Sandell’s sensitivity of 0.0046 μg of iron per cm2. On the basis of this sensitive color reaction, a simple, rapid, selective, and highly reproducible method for the extractive spectrophotometric determination of microgram amounts of iron in various drug, biochemical and biological samples has been developed. The method is free from most of the common metal ions and commonly used sequestering agents.
Synthesis of Standardized Building Blocks as a β-d-Mannosyl Donors with a Temporary Protection to be 3,6-Di-O-glycosyl Acceptors, for Constructing the Inner Core of Glycoproteins and Artificial Antigens
Authors: El Ashry El Sayed H , Schuerch Conrad
Published: July 2006

A synthetic scheme has been achieved for the core block of glycoproteins having d-mannose configuration, which is standardized to be a 3,6-di-O-glycosyl acceptor and react stereoselectively as a β-d-mannosyl donor. The synthesis was started by methyl 2,3-O-isopropylidene-α-d-mannopyranoside, which upon benzylation, deisopropylidenation, and selective acetolysis of the 6-O-benzyl group afforded the corresponding tetraacetate, which could be converted to 3,6-di-O-allyl-4-O-benzyl-1,2-O-(1-methoxyethylidene)-β-d-mannopyranose. The orthoester could be separated into the exo and endo isomers. Hydrolysis of the orthoester ring followed by reaction with mesyl chloride gave 3,6-di-O-allyl-4-O-benzyl-2-O-mesytl-α-d-mannopyranosyl chloride, that upon reaction via its 1-O-trifluoroethanesulfonate with 2-[4-(p-toluenesulfonamido)phenyl]ethanol gave the corresponding glycosides in β:α ratio of 3:1. Deallylation of the β-glycosides gave the diol which are suitable for branching and could react selectively at the 6-position allowing its potential for glycosylation by different glycosyl donors.
Silver cis-Tetrachlorohydroxonitrosylruthenate (2–)
Authors: Kamata Yasuhiro , Miki Eiichi , Mizumachi Kunihiko , Ishimori Tatsujiro
Published: July 2006

A new chloronitrosylruthenate ion was separated from the hydrolysis mixture of [RuCl5(NO)]2− by the anion-exchange method, and it formed Ag2[RuCl4(OH)(NO)] on the addition of silver nitrate. The anion of the silver salt was found to have the cis form on the basis of its IR spectrum.
Photochemical Isomerization of 2-Pyridyl- and 2-Pyrazinyl-1,2-benzisothiazol-3(2H)-ones
Authors: Kamigata Nobumasa , Iizuka Hirokazu , Kobayashi Michio
Published: July 2006

The irradiation of 2-pyridyl- and 2-pyrazinyl-1,2-benzisothiazol-3(2H)-ones in benzene resulted in the formation of benzopyrido- and benzopyrazinothiazepinones, respectively. A mechanism involving a biradical species is proposed for this reaction.
Spin-Equilibrium Behavior in Solution of an Iron(III) Complex [Bis[3-(3-methoxysalicylideneamine)propyl]amino-O,N,N′,N″,O′](pyridine)iron(III) Tetraphenylborate
Authors: Ohyoshi Akira , Honbo Jukichi , Matsumoto Naohide , Ohta Shoichi , Sakamoto Shingo
Published: July 2006

The title iron(III) complex with a spin equilibrium between high-spin(S=5/2) and low-spin(S=1/2) has been investigated by means of the temperature dependences of the magnetic susceptibilities (the Evans 1H NMR technique), the electronic spectra, and the cyclic voltammetry. The pure electronic spectra for high-spin and low-spin species were evaluated from the observed electronic spectra and the equilibrium constants obtained from the magnetic data. The electron-transfer entropy for the Fe3++e→Fe2+ process(ΔSet) was obtained as 205 JK−1 mol−1 from the temperature dependence of the cyclic voltammogram.
The Microwave Spectrum of (E)-(Propinaldehyde Oxime)
Authors: Yoshida Kazuhiko , Sakaizumi Takeshi , Ohashi Osamu , Yamaguchi Ichiro
Published: July 2006

Microwave spectra of propionaldehyde oxime and its deuterated derivatives (CH3CH2CH=NOD) were observed in the frequency region from 10 to 35 GHz. Several a-type R-branch transitions were identified and the following rotational constants(MHz) in the vibrationally ground state were determined to be: A=19400±400, B=2278.16±0.03, and C=2204.09±0.03 for the normal species, and A=19000±400, B=2194.31±0.02, and C=2128.40±0.02 for the deuterated species. The spectrum analyzed in this work has been concluded from the rotational constants to be due to a ac,E-conformer.
Site-Selective Photochemical Ene Reaction of 2-Methylene-1,2-dihydronaphthalene
Authors: Sugimoto Akira , Sakamoto Satoshi , Suyama Kanji , Yoneda Shigeo
Published: July 2006

The title compound, formed by the photolysis of 2-(2-anilinoethyl)naphthalene, reacted with olefins having a conjugated double bond to give an ene reaction product under irradiation conditions.
Hydrolysis of p-Nitrophenyl Hexanoate in Hydrophobic Aggregate System
Authors: Kodaka Masato , Fukaya Toshio , Kikkawa Masayoshi
Published: July 2006

Hydrolysis of p-nitrophenyl hexanoate in the presence of azide ion (N3−) was accelerated by tetraheptylammonium bromide (1), which has four long alkyl chains. In contrast to 1, the other tetraalkylammonium salts which have shorter alkyl chains, (2)–(5), did not elevate the reactivity. p-Nitrophenyl acetate, less hydrophobic substrate, was not hydrolyzed so efficiently even in the presence of 1.
Reductive and Regioselective Cleavage of Oxetanes Assisted by the Neighboring Hydroxyl
Authors: Kato Michiharu , Kitahara Haruo , Yoshikoshi Akira
Published: July 2006

On exposure to lithium aluminium hydride, 1,6-dioxadispiro[2.0.3.4]undecane and 5-methl-2-oxaspiro[3.5]nonan-5-ol gave 1,2-dimethyl-c-2-(hydroxymethyl)-r-1-cyclohexanol (5) which was produced from regioselective C–O bond cleavage of oxetane rings by an intramolecular attack of hydride. The stereochemistry of 5 was confirmed by an unambiguous synthesis based on the Sharpless oxidation of 1-methyl-2-methylenecyclohexanemethanol.
Effective Synthesis of 2-[4-(3-Methyl-2-butenyl)phenyl]propionic Acid via Hydromagnesation Reaction with Nickel or Titanium Catalysts
Authors: Amano Takehiro , Ota Tomomi , Yoshikawa Kensei , Sano Tatsuhiko , Ohuchi Yutaka , Sato Fumie , Shiono Manzo , Fujita Yoshiji
Published: July 2006

2-[4-(3-Methyl-2-butenyl)phenyl]propionic acid was synthesized in 82% yield via nickel(II) chloride or dichlorobis[η5-cyclopentadienyl]titanium-catalyzed hydromagnesation of 1-(3-methyl-2-butenyl)-4-vinylbenzene obtained in ca. 63–68% yield by the coupling reaction of 4-(3-methyl-2-butenyl)phenylmagnesium chloride with vinyl chloride.
A Study of the Reactivity of Surface-Adsorbed Oxygen Species with C2H6 on V2O5/SiO2
Authors: Iwamatsu Eiji , Aika Ken-ichi , Onishi Takaharu
Published: July 2006

The properties and reactivities of surface oxygen species including O− on V2O5/SiO2 were studied in connection with the oxidative dehydrogenation of C2H6 by N2O. O− was formed through N2O on reduced V2O5 supported on SiO2 which had been prepared from tetraethyl silicate, whereas it was not formed on V2O5 supported on SiO2 obtained from other sources. One mole of O− on V2O5/SiO2 was found to react with one mole of C2H6 at 298K. No oxygen species other than O− reacted with C2H6 at 298K. The surface reaction mechanism was discussed, and ethoxide was considered to be one of the surface intermediates. All the other surface oxygens but O− reacted with C2H6 above 573K. Since a catalytic oxidative dehydrogenation reaction of C2H6 was active above 573K, the surface oxygens other than O− were considered to be responsible for this reaction. The possibility of O− as the reaction intermediate was also discussed.
Phase-Shift Studies of the Quenching of NH(c1Π) by HN3, NO, CO, and CO2
Authors: Sasaki Shun-ichiro , Tsunashima Shigeru , Sato Shin
Published: July 2006

Absolute cross sections for quenching NH(c1Π) by the use of several inorganic molecules were determined at room temperature by using a phase-shift method. The NH(c1Π) radicals were produced by the photolysis of HN3 using an amplitude-modulated Xe-resonance lamp. The results obtained were as follows: 0.01(He), 12(HN3), 48(NO), 49(CO), and 30(CO2) in units of 10−16 cm2. In the case of NO, the 336 nm emission was enhanced, which suggests that NO quenches NH(c1Π) to NH(A3Π). From the phase difference between the 325 and 336 nm emissions, the quenching cross-section of NO for NH(A3Π) was estimated to be 60×10−16 cm2.
Studies of the Metal Complexes of Cyclohexane Derivatives. IX. The Preparation and Properties of Platinum(II) Complexes Containing Methyl Derivatives of cis-1,2-Cyclohexanediamine
Authors: Saito Reiko , Kidani Yoshinori
Published: July 2006

Four 1,2-diamine ligands, (1RS,2SR)-1-methyl-1,2-cyclohexanediamine(1m-chxn), (1R,2S,3R)-3-methyl-1,2-cyclohexanediamine(R,S,R-3m-chxn), (1S,2R,4R)-4-methyl-1,2-cyclohexanediamine(S,R,R-4m-chxn), and (1R,2S,4R)-4-methyl-1,2-cyclohexanediamine(R,S,R-4m-chxn), were prepared. The mixed-ligand complexes of the [PtXL]2+ type(X=(NH3)2, 1,2-ethanediamine, meso-2,3-butanediamine, and 2,3-dimethyl-2,3-butanediamine, L=each m-chxn) were synthesized and characterized by means of their electronic, circular dichroism, and 13C NMR spectra. The chelate ring formed by S,R,R-4m-chxn was almost conformationally fixed to take a δ conformation, while the chelate rings of 1 m-chxn, R,S,R-3m-chxn, and R,S,R-4m-chxn easily interchange between δ and λ conformations. The stereochemistries of these three complexes are attributable to the conformational requirements for both the cyclohexane ring and the chelate ring, for which synchronous inversions are presumed.
Synthetic Approach toward Antibiotic Ezomycins. I. Synthesis of 5-Amino-5-deoxyoctofuranose-(1,4) Derivatives by Henry Reaction and Their Stereochemistry
Authors: Sakanaka Osamu , Ohmori Takashi , Kozaki Shuji , Suami Tetsuo , Ishii Toshio , Ohba Shigeru , Saito Yoshihiko
Published: July 2006

Ezomycins were discovered in a fermentation beer of Streptomyces species as antibiotics, which consisted of aminoocturonic acid, aminoglucuronic acid and base. As a part of a total synthesis of ezomycins, the title compounds have been synthesized. A KF-catalyzed Henry reaction between a nitropentose and a glyceraldehyde derivative gave a nitro alcohols mixture. Hydrogenation of the intact mixture, followed by N-acetylation afforded three diastereomers. The absolute configurations of the newly-introduced chiral centers were established by chemical methods and a X-ray crystal structure analysis.
Synthesis of 29-Norlanostane Derivatives
Authors: Naora (nee Namikawa) Misuzu , Murae Tatsushi , Tsuyuki Takahiko , Takahashi Takeyoshi
Published: July 2006

As authentic samples for identification of 29-norlanostane derivatives isolated from plant fossil, 29-norlanostan-24-one and -23-one, 29-norlanost-9(11)-en-24-one, -23-one, and -3-one, 29-norlanost-7-en-3-one, and 29-norlanostan-3-one were synthesized from a commercial lanosterol containing dihydrolanosterol.
Transition-Metal Complexes of Pyrrole Pigments. XXII. Photoredox Behavior of Oxo(tetra-p-tolylporphinato)molybdenum(V) Complexes
Authors: Matsuda Yoshihisa , Takaki Toshihiko , Murakami Yukito
Published: July 2006

Photochemical reduction of oxomolybdenum(V) complexes of 5,10,15,20-tetra-p-tolylporphine, [Mov(X)(ttp)], was investigated under irradiation with the visible light in benzene, where X stands for an axial ligand placed trans to the oxo group. Irradiation of [MovO(X)(ttp)] resulted in a homolytic cleavage of the Mo–X bond to afford [MoIVO(ttp)] and a radical species generated from the axial ligand (X). The reduction rate was controlled by the nature of the Mo–X bond, and a complex with less ionic character of the axial bond was more reactive in the homolysis process. The bulkiness of the axial alkoxo ligands may provide two different effects which are opposite to each other on the reactivity: (i) The repulsive interaction between an axial ligand and the equatorial ttp accelerates the homolysis of the Mo–X bond; (ii) the diffusion rate of the radical species, generated by the photochemical cleavage of the axial coordinate bond, from the coordination sphere is progressively retarded as the bulkiness of the alkoxo ligand increases. The second effect seems to be more pronounced for the present photochemical reaction. The photochemical reduction of [MoVO(X)(ttp)] is essentially composed of two sequential steps, photochemical cleavage of the Mo–X bond and diffusion of the radical species from the coordination sphere. Reoxidation of [MoIVO(ttp)] under aerobic irradiation conditions afforded [MoVO(OH)(ttp)] and [(MoVO(ttp))2O] via the postulated intermediate formation of [MoV(OO·)(ttp)].
Flameless Atomic-Absorption Spectrometric and Differential-Pulse Polarographic Determination of Cadmium after Coprecipitation with Hafnium Hydroxide
Authors: Ueda Joichi , Yamazaki Natsuko
Published: July 2006

Using the coprecipitation method with hafnium hydroxide, the flameless atomic-absorption spectrometric and the differential-pulse polarographic determinations of cadmium have been studied. The collecting ability of hafnium hydroxide for cadmium is excellent; from 0.01 to at least 1000 μg of cadmium in 50–400 cm3 of a sample solution is coprecipitated quantitatively. The presence of hafnium hydroxide does not interfere with either method of determining cadmium. Of the diverse ions examined, there are no ions which interfere with the flameless atomic-absorption spectrometric determination, even if they are present in a concentration of at least 5000 times that of cadmium; as for the differential-pulse polarographic determination, only indium interferes when present in small amounts. The linear calibration curves through the point of origin were obtained over the range of 0.4–4 ng cm−3 of cadmium for the former method and 0.04–40 μg cm−3 for the latter method. In the proposed methods, the flameless atomic-absorption spectrometric determination was successfully applied to the analysis for trace amounts of cadmium in river-water samples.
From Penicillin to Penem and Carbapenem. IX. C1-Unit Introduction and the Carbapenam Synthesis from the Penicillin Molecule
Authors: Fujimoto Katsumi , Iwano Yuji , Hirai Koichi
Published: July 2006

An effective method for (R)-1-hydroxyethylation of benzyl bis(phenylseleno)penicillanate is described. The hydroxyethylated product was transformed into the 4-methylsulfonyl- and 4-phenylsulfonyl-2-azetidinone derivatives. These monocyclic compounds were reacted with potassium cyanide under two-phase conditions to give the 4-cyano-2-azetidinone derivative (C1-unit introduction) in high yield. The cyano group was then converted into the iodomethyl group. Using the 4-iodomethyl-2-azetidinone derivative an isopenam derivative was synthesized. Furthermore, carbapenam derivative were also constructed by a novel [3+2] cyclization reaction between 4-iodomethyl-2-azetidinone and dimethyl 2-methylthio- and 2-phenylthiofumarate.
Total Synthesis of (−)-Vitrenal and Its Biological Activity
Authors: Kodama Mitsuaki , Tambunan Usman S F , Tsunoda Tetsuto , Itô Shô
Published: July 2006

(−)-Vitrenal, the enantiomer of the natural sesquiterpene aldehyde isolated from a liverwort, has been synthesized starting from (+)-3-carene, and its activity as a plant-growth regulator has been tested.
Cyclodextrin-Catalyzed Hydrolysis of Enantiomeric Esters Showing Stereoselectivity
Authors: Ihara Yasuji , Nakanishi Eiji , Nango Mamoru , Koga Joichi
Published: July 2006

The rate constants for hydrolysis of the enantiomers of amino acid nitrophenyl esters have been determined at pH 9.00 and pH 10.0 in the presence of α- or β-cyclodextrin. α- and β-Cyclodextrins cause stereoselective acceleration in the hydrolysis of m-substituted enantiomers. On the other hand, less stereoselectivity is observed in the hydrolysis of p-substituted enantiomers. The stereoselective properties are discussed in the light of cyclodextrin-ester dissociation constants and thermodynamic parameters of the reaction.
Conductivity of Lithium Salts in the Mixed Systems of High Permittivity Solvents and Low Viscosity Solvents
Authors: Matsuda Yoshiharu , Morita Masayuki , Tachihara Fumitsugu
Published: July 2006

Electrolytic conductivities of LiClO4 and LiPF6 have been investigated in the mixed systems of the high permittivity solvents and low viscosity solvents. Propylene carbonate (PC), sulfolane (S), and dimethyl sulfoxide (DMSO) were used as the high permittivity solvents, and 1,2-dimethoxyethane (DME) and tetrahydrofuran (THF) as the low viscosity solvents. The conductivity of 1 mol dm−3 LiClO4 has a miximum in the mixed solvent with 40–80 m/o ether for every system. The conductance improvement by solvent-blending was qualitatively described in terms of a favorable combination of high permittivity and low viscosity of each component. The maximum conductivity of 1 mol dm−3 LiClO4 increased in the order of S<PC<DMSO for the systems containing THF. The difference in the order of maximum conductivity between DME and THF was interpreted by ion-solvent interactions, whose measure is generally expressed by the donor and acceptor properties of the solvent. The LiPF6 solutions had much higher conductance than those of LiClO4, especially in high DME concentration regions.
Fluorescence Lifetimes of 9-Methylanthracene in Supersonic Free Jets. A Level Inversion between S1 and T2 States upon the Phase Change from Solution to Gas
Authors: Tanaka Fujio , Hirayama Satoshi , Yamashita Shigeru , Shobatake Kosuke
Published: July 2006

Fluorescence lifetimes measured for 9-methylanthracene in supersonic free jets confirm the occurrence of nonradiative decay at the vibrationless level of S1 that has been suggested from the measurement of the fluorescence yield. The nonradiative decay constants in the isolated and condensed phases have been compared from the viewpoints of relative positions of S1 and T2 levels and of the magnitude of the energy gap.
The Crystal Structure of a Conformational Isomer of Teucrin P1 from Teucrium Gnaphalodes
Authors: Zheng Zeyong , Yamane Takashi , Ashida Tamaichi , Morita Masaya , Kato Natsuki , Iwashita Takashi , Nakanishi Koji
Published: July 2006

The crystal structure of an isomer of Teucrin P1 isolated from Teucrium gnaphalodes has been determined by the X-ray method. Crystal data: orthorhombic, P212121, a=13.849(4), b=15.545(3), c=7.896(2) Å, Z=4. The final R value is 0.048 for 1247 observed reflections with Fo>2σ(Fo). The structure is disordered, and two kinds of components (molecules) with different conformations coexist in the crystal. The major component exists with a probability of 0.74, while the minor one with 0.26. A tetrahydropyran ring in the former takes a boat form, while the latter a chair form, indicating that in this complex fused-ring system a boat form of the tetrahydropyran ring is more stable than a chair one. The conformation of the major component is the same as that of naturally occurring Teucrin P1, apart from the orientation of a furan ring.
A High-Resolution Solid-State 13C NMR Study of (1→3)-β-d-Glucans from Various Sources. Conformational Characterization as Viewed from the Conformation-Dependent 13C Chemical Shifts and Its Consequence to Gelation Property
Authors: Saitô Hazime , Tabeta Ryoko , Sasaki Takuma , Yoshioka Yûko
Published: July 2006

High-resolution solid-state 13C NMR spectra of a variety of (1→3)-β-d-glucans in the solid state were recorded by means of cross polarization-magic angle spinning (CP–MAS) NMR spectroscopy. We found that the C-1 and C-3 peak-positions of these glucans are significantly displaced (up to 8 ppm) depending upon variety of samples used. Interestingly, these glucans obtained by lyophilization or spray-drying possess regular secondary structures as detected by displacements of the conformation-dependent 13C chemical shifts. In fact, at least four kinds of molecular conformations were distinguishable by 13C NMR spectroscopy. Gel-forming ability of linear (1→3)-β-d-glucans, however, was related to the presence of a single particular conformation without involving any other form. By contrast, gel-formation was noted for a branched glucan whose conformation is similar to that of a linear glucan without gel-forming ability. Further, conformation of all these linear and branched (1→3)-β-d-glucans turned out to be the same when solid samples were prepared by lyophilization from DMSO solution.
Partial Molar Enthalpy of Solution for Tris(2,4-pentanedionato)cobalt(III) in Mixed Solvents of Water and Dimethyl Sulfoxide
Authors: Yoshimura Yasuki , Sato Nobuyoshi , Kikuchi Makoto
Published: July 2006

The solubility (Xs) of tris(2,4-pentanedionato)cobalt(III) ([Co(acac)3]) in mixed solvents of water and dimethyl sulfoxide (DMSO) with various compositions was determined over the temperature range 20–60 °C. It was found that the experimental values of Xs could be satisfactorily fitted to lnXs=A(1⁄T)+BlnT+C and the partial molar enthalpy of solution (Δ\barHs) at 25 °C for [Co(acac)3] was estimated from slopes of the solubility curves. When Δ\barHs was plotted against the mole fraction of DMSO (XDMSO), a clear maximum was found at about XDMSO=0.3. This composition profile of Δ\barHs is discussed in connection with the internal pressure of a mixture of water and DMSO. A method to estimate an approximate value of the partial molar enthalpy of hydrophobic hydration (Δ\barHh) in an aqueous DMSO mixture of [Co(acac)3] is also presented by using the solubility data in mixtures with a lower XDMSO than 0.14.
Palladium-Catalyzed Reaction of 2-Vinyl-2,3-dihydrobenzofurans and Chroman with Nucleophiles
Authors: Hosokawa Takahiro , Kono Takanori , Uno Toru , Murahashi Shun-Ichi
Published: July 2006

Reaction of 2,3-dihydro-2-vinylbenzofuran with nucleophiles (NaCH(COOEt)2 and PhNHCH3) in the presence of palladium catalysts such as Pd(PPh3)4 and PdCl2(PR3)2 (R=Ph and Et) gives 2-(2-butenyl)phenols (46–76% yields) in which nucleophiles are incorporated into the methyl group of the butenyl moiety. 2-Vinylchroman undergoes the same type of reaction where only the palladium complex bearing PEt3 ligand is effective. The effectiveness of PEt3 ligand is also observed in the reaction of 2,3-dihydro-2-isopropenylbenzofuran with diethyl sodiomalonate leading to 3-ethoxycarbonyl-4-(2-methyl-1-propenyl)-2-chromanone.