bluuebunny/crossref_metadata_2025 huggingface dataset:
The Synthesis of Some Dimethylpyranocoumarins and Isopropenyldihydrofuranocoumarins
Authors: Yamaguchi Seiji , Miyakawa Ryozo , Yonezawa Shinobu , Kawase Yoshiyuki
Published: July 2006

Two pyranocoumarins, 7,7-dimethyl-2(7H)-benzo[1,2-b:4,5-b′]dipyranone and 8,8-dimethyl-2(8H)-benzo[1,2-b:5,4-b′]dipyranone, and three dihydrofuranocoumarins, 2-isopropenyl-1,2-dihydro-8-furo[1,2-f][1]benzopyranone, 2-isopropenyl-2,3-dihydro-6-furo[1,2-e][1]benzopyranone, and 2-isopropenyl-2,3-dihydro-7-furo[2,1-e][1]benzopyranone, were synthesized by an effective pyrone-ring formation in corresponding o-hydroxybenzaldehyde derivatives. And, 2-[1-(hydroxymethyl)vinyl]-1,2-dihydro-8-furo[1,2-f][1]benzopyranone was also synthesized selenium dioxide oxidation.
Diastereoselective Reduction of α-Keto Amides Having trans-2,5-Disubstituted Pyrrolidine as a Chiral Auxiliary
Authors: Kawanami Yasuhiro , Fujita Izumi , Asahara Shouko , Katsuki Tsutomu , Yamaguchi Masaru
Published: July 2006

The reduction of α-keto amides derived from (2R,5R)-trans-2,5-bis(methoxymethoxymethyl)pyrrolidine [(R)-BMOMP, 1] with LiBEt3H or KBEt3H proceeded with high diastereoselectivity (up to 99% ds) to afford the corresponding α-hydroxy amides in good yields. The additive effect of crown ethers or metallic salts on the stereoselectivity was also examined.
Analysis of Isotropic 1H and 13C NMR Shifts of Low-Spin FeIII Complexes: Tetracyano(1,2-ethanediamine)ferrate(III) and Tetracyano(N,N′-dimethyl-1,2-ethanediamine)ferrate(III)
Authors: Kuroda Yoshitaka , Goto Masafumi , Sakai Tomoya
Published: July 2006

1H NMR spectra of low-spin d5 complexes, [FeIII(CN)4(en)]− and [FeIII(CN)4(s-Me2en)]− (en=1,2-ethanediamine, s-Me2en=N,N′-dimethyl-1,2-ethanediamine), were measured at 185–323 K. These complexes showed a non-Curie behavior. The spin states of the complexes were determined by an analysis of the g values from the ESR spectrum of a polycrystalline sample of [FeIII(CN)4(en)]− measured at liquid-helium temperatures. The isotropic shifts for the 1H and 13C nuclei, δiso, were separated into Fermi contact shifts, δcon, and dipolar shifts, δdip and the strong dependence of δiso on the location of ligand nuclei was found to be due to the different δcon as well as δdip. A combination of information concerning ESR and NMR enabled the assignment of the g values obtained from a polycrystalline sample, i.e. gxx=3.15, gyy=1.99, and gzz=0.82, and determination of spin-orbit coupling constant, ζ=160 cm−1.
Kinetic Study on Hydrogenation of Isoquinoline over Supported Ruthenium Catalysts
Authors: Okazaki Hiroshi , Soeda Mahito , Ikefuji Yoshio , Tamura Ryuji , Mochida Isao
Published: July 2006

The hydrogenation of isoquinoline (1) to isomeric decahydroisoquinoline (4) via 1,2,3,4-tetrahydroisoquinoline (2) or 5,6,7,8-tetrahydroisoquinoline (3) was kinetically studied over supported ruthenium catalysts under 50–100 atm hydrogen pressure at 135–170 °C. The results showed that the reaction proceeds mainly via 2 over ruthenium on carbon, and via 2 and 3 competitively over ruthenium on alumina. Such reaction features are explained from the view points of their adsorption and the activation of the molecules on the catalysts based on quantum chemical indices. The acidic nature of alumina support exhibited a preference of nitrogen lone-pair defining the adsorption of substrates, and consequently influencing on the reaction route. The proposed approach distinguished the present catalyst from Raney nickel examined in a previous paper. The noble and base metals may interact differently with the substrate, although both metals are classified as “soft”.
Predictions of the Features of the Potential Energy Surfaces from the Diatomic Constants: A Series of Collinear Abstraction Reactions, H+HX (X=F, Cl, Br, I)
Authors: Tanaka Noboru
Published: July 2006

A new method, to predict the feature of potential energy surface (PES) from the diatomic constants of reactants molecules, is presented. The PES is calculated by using our proposed semi-empirical method (MT method). Based on MT method, a graphical method is introduced to investigate the relations between the features of the PES and the diatomic constants. Using these relations as guideline, the features of the PES for a series of linear abstraction reactions, H+HX=HH+X with X=F, Cl, Br, and I, are deduced in a simple manner. The PES thus deduced are in good agreement with available experimental and theoretical information.
Dielectric Behavior and Intermolecular Association for Octanol Isomers. Existence and Transformation of a Nonpolar Cyclic Polymer
Authors: Shinomiya Toshiomi
Published: July 2006

The equilibrium dielectric constants of ten isomeric C8H17OH and binary mixtures of 1-butanol in four isomeric C8H17OH have been measured at temperatures from 135 to −55 °C. These isomeric C8H17OH can be grouped roughly into three types, namely, more polar, intermediate, and more sterically hindered alcohols. The dielectric behavior of each of the three types can be explained by equilibrium among a linear hydrogen-bonded chain polymer (CHAIN), a free monomer inclusive of a chain dimer and trimer (MONOMER), and a nonpolar cyclic polymer (RING). As the temperature decreases, MONOMER transforms into CHAIN for more polar alcohols. Two transformations, MONOMER into RING at high temperatures and RING into CHAIN at low temperatures, occur for intermediate alcohols. MONOMER transforms into RING and CHAIN can not be observed for more hindered alcohols. However, a transformation of RING into CHAIN can be observed by adding 1-butanol to the more hindered alcohols. CHAIN is most stable. When formation of CHAIN becomes difficult, RING can be formed. The transformation is dependent on temperature, molecular geometry, and the amount of 1-butanol in the mixture.
Spectroscopic Evidence of α,α-Dihydroxy Ketone in Biacetyl Aqueous Solutions
Authors: Miyata Kaori , Nakashima Kenichi , Koyanagi Motohiko
Published: July 2006

From the analysis of emission, excitation, absorption, and 1H NMR spectra of 2,3-butanedione (i.e., biacetyl), it has been established that about two thirds of the molecule in aqueous solutions exists as 3,3-dihydroxy-2-butanone (i.e., a hydrated form of biacetyl). For the first time, two different types of emission are discriminated: Emission is mostly due to the fluorescence spectrum of the monoketone upon irradiation of light with a shorter wavelength than 320 nm while it is due to the strong phosphorescence spectrum of biacetyl itself upon irradiation of light with a longer wavelength than 350 nm. The almost stoichiometric molecular rearrangement from the hydrated (monoketone) form in a water phase to the ordinary (diketone) form in a hydrocarbon phase has been found to take place.
Preparation of Tetraalkylsilanes from Trichloromethylsilane and Trioctylaluminum
Authors: T. Sabourin Edward , Onopchenko Anatoli
Published: July 2006

The synthesis of methyltrioctylsilane has been achieved in a single-step from commercially available trichloromethylsilane and trioctylaluminum. Co-products resulting from alkyl group redistribution are minimized by addition of sodium or lithium halides. Use of potassium or rubidium halides drastically changes the course of the reaction to produce methyldioctylsilane as the major product.
Induced Circular Dichroism and Molecular Orientations of β-Cyclodextrin Inclusion Complexes with 9,10-Anthraquinone and 9,10-Phenanthrenequinone
Authors: Ata Masafumi , Kubozono Yoshihiro , Suzuki Yasunobu , Aoyagi Makoto , Gondo Yasuhiko
Published: July 2006

The induced circular dichroism (ICD) spectra of β-cyclodextrin inclusion complexes with 9,10-anthraquinone and 9,10-phenanthrenequinone have been measured, and the electronic structures and molecular orientations of the guests are discussed in terms of the ICD signs and theoretical results.
The Determination of the Poly(oxyethylene) Oligomer Distribution in a Non-ionic Surfactant by Means of Thin-Layer Chromatography
Authors: Saito Yoshihiro , Sato Takatoshi , Anazawa Ichiro
Published: July 2006

The analytical method for determining the distribution of the polymerization degree of the oxyethylene (OE) chain in commercially available poly(oxyethylene) alkyl ether (CmEn) was investigated by means of thin-layer chromatography with flame-ionization detection (TLC-FID). It was found that the method of calculating the relative response factors of every OE chain to FID could be determined, and the analysis of the distribution of the polymerization degree of the OE chain in commercially available CmEn became possible using the TLC-FID method.
Electronic Properties of New Organic Conductors Based on 2,7-Bis(methylthio)-1,6-dithiapyrene (MTDTPY) with TCNQ and p-Benzoquinone Derivatives
Authors: Imaeda Kenichi , Enoki Toshiaki , Mori Takehiko , Inokuchi Hiroo , Sasaki Mitsuru , Nakasuji Kazuhiro , Murata Ichiro
Published: July 2006

The electronic properties of charge-transfer (CT) complexes based on a new organic donor MTDTPY with TCNQ and p-benzoquinone derivatives (fluoranil (FLL), chloranil (CHL), bromanil (BRL), and DDQ) have been investigated by means of electrical conductivity, thermoelectric power, ESR, and band calculation. β-MTDTPY–TCNQ, MTDTPY–CHL, and MTDTPY–BRL show a metallic electrical conduction. MTDTPY–CHL and MTDTPY–BRL are the first organic metals among the CT complexes with p-benzoquinone derivatives. The metal–insulator (M-I) transition takes place around 110, 240, and 125 K for β-MTDTPY–TCNQ, MTDTPY–CHL, and MTDTPY–BRL, respectively. The sharp ESR linewidth and large anisotropy of the transfer integral for β-MTDTPY–TCNQ and MTDTPY–CHL suggest a one-dimensional electronic property. Thus, the M-I transition for these complexes is considered to be caused by a Peierls instability. MTDTPY–CHL undergoes a first-order phase transition in the semiconducting phase. This phase transition disappears by applying pressure.
Chiral Aryl Grignard Reagents-Generation and Reactions with Carbonyl Compounds
Authors: Kaino Makoto , Ishihara Kazuaki , Yamamoto Hisashi
Published: July 2006

Chiral aryl Grignard reagents are generated in situ from homochiral 2-halobenzaldehyde acetal, t-butyllithium, and magnesium bromide. These reagents react with aromatic aldehydes to moderate diastereoselectivities.
A Facile Synthesis of 4-Hydroxy- and 4-Aminoindoles through Corresponding Indolines
Authors: Tanaka Hideo , Murakami Yasuo , Aizawa Takao , Torii Sigeru
Published: July 2006

2-(2,6-Diaminophenyl)ethanol can be conducted to 4-hydroxyindoline under heating in aqueous 70% phosphoric acid, and to 4-aminoindoline under heating in aqueous 30% sulfuric acid. Both 4-hydroxy- and 4-aminoindoles were obtained by dehydrogenation of the indolines under refluxing in 1,4-dimethylbenzene over palladium on charcoal.
Spectral Studies of Some Coordination Complexes of Pt(II) and Rh(I) with Benzothiazolines
Authors: Garg Archana , Tandon Jagdish Prasad
Published: July 2006

The present paper describes the synthesis and structural features of platinum(II) and rhodium(I) complexes of some benzothiazolines derived by the condensation of various heterocyclic aldehydes viz. 2-pyridinecarbaldehyde, 2-furancarbaldehyde, and 2-thiophenecarbaldehyde. The resulting complexes have been characterized by elemental analyses, conductance measurements and molecular weight determination. The mode of bonding and geometry of these complexes have been suggested on the basis of IR, 1H NMR, electronic spectra, and magnetic studies.
Preparation and Characterization of Rhodium(III) Complexes Containing (2-Aminoethyl)dimethylphosphine (edmp) or 1,2-Bis(dimethylphosphino)ethane (dmpe). Structures of fac-[Rh(edmp)3]3+, trans(Cl,Cl),cis(P,P)-[RhCl2(edmp)2]+, and trans-[RhCl2(dmpe)2]+
Authors: Simonsen Kim P , Suzuki Nahomi , Hamada Masatoshi , Kojima Masaaki , Ohba Shigeru , Saito Yoshihiko , Fujita Junnosuke
Published: July 2006

The fac-[Rh(edmp)3]3+ (edmp=(2-aminoethyl)dimethylphosphine), trans(Cl,Cl),cis(P,P)-[RhCl2(edmp)2]+, and trans-[RhCl2(dmpe)2]+ (dmpe=1,2-bis(dimethylphosphino)ethane) complexes were prepared and the molecular structures were determined by the single crystal X-ray diffraction method. Crystal data and final R values are: fac-[Rh(edmp)3]Br3·3H2O, orthorhombic, Pna21, a=26.750(4), b=10.125(1), c=9.592(1) Å, V=2598.2(5) Å3, Z=4, R=0.039 for 1590 observed unique reflections. trans(Cl,Cl),cis(P,P)-[RhCl2(edmp)2]PF6, monoclinic, P21/a, a=18.197(4), b=12.574(2), c=8.615(1) Å, β=96.59(2)°, V=1958.2(6) Å3, Z=4, R=0.032 for 3379 reflections. trans(Cl,Cl),cis(P,P)-[RhCl2(edmp)2]ClO4, triclinic, P\bar1, a=13.122(2), b=17.952(2), c=12.343(2) Å, α=91.65(2), β=102.46(2), γ=80.74(1)°, V=2802.0(7) Å3, Z=6, R=0.070 for 7513 reflections, trans-[RhCl2(dmpe)2]CF3SO3, monoclinic, P21/a, a=13.166(2), b=24.337(4), c=8.002(2) Å, β=95.95(2)°, V=2550.1(8) Å3, Z=4, R=0.040 for 3201 reflections. It was found that the shorter the Rh–P bond length, the larger the trans Rh–N bond elongation. The mean Rh–P bond distance in trans-[RhCl2(dmpe)2]CF3SO3 (2.337(2) Å) is longer than those in fac-[Rh(edmp)3]Br3·3H2O (2.283(4) Å) and trans(Cl,Cl),cis(P,P)-[RhCl2(edmp)2]PF6 (2.252(2) Å). A series of complexes of trans(X,X),cis(P,P)-[RhX2(edmp)2]+ (X=Cl, Br, I) and trans-[RhX2(dmpe)2]+ (X=Cl, Br) were also prepared and their absorption spectra were compared with one another and with those of the corresponding cobalt(III) complexes.
Synthesis, Magnetic Property, and Crystal Structure of Imidazolate-Bridged Manganese(III)–Copper(II) Dinuclear Complex
Authors: Matsumoto Naohide , Okawa Hisashi , Kida Sigeo , Ogawa Takanori , Ohyoshi Akira
Published: July 2006

The synthesis, crystal structure, and magnetic property of an imidazolate-bridged manganese(III)–copper(II) dinuclear complex [Mn(salen)Cu(A)]BPh4 are described, where [H2salen]=N,N′-disalicylideneethylenediamine, [H2A]=4-(6-methyl-8-oxo-2,5-diazanonane-1,5,7-trienyl)imidazole, and BPh4=tetraphenylborate. The X-ray analysis confirmed an imidazolate-bridged manganese(III)–copper(II) dinuclear structure, in which the coordination geometries of the manganese(III) and copper(II) ions are square pyramid and square planar, respectively. The apical position of the manganese(III) ion is occupied by an imidazolate nitrogen N(3) of the [Cu(A)] moiety with the bond distance of Mn–N(3) 2.165(5) Å. As the temperature is lowered, the effective magnetic moment per molecule decreases gradually from 5.17 B.M. at 300.2 K, reaches the minimum value 4.44 B.M. at 24.9 K, and then increases to 4.73 B.M. at 4.2 K, indicating that antiferro- and ferro-magnetic interactions are co-operative in the complex.
Gallium Coprecipitation Associated with Magnesium for Preconcentration of Trace Metals in Seawater
Authors: Akagi Tasuku , Fuwa Keiichiro , Haraguchi Hiroki
Published: July 2006

The coprecipitation of trace metals with gallium has been investigated in detail especially with respects to the role of magnesium ion in saline or seawater. Gallium does not precipitate even at pH 9 when magnesium ion does not exist. The concentration of gallium in the precipitate increased with increasing that of magnesium in solution. The recoveries of trace metals also showed strong dependence on the concentrations of both gallium and magnesium in the aqueous solution.
A Cross-Coupling Reaction of Methylsulfinylarene
Authors: Wakabayashi Shoji , Tanaka Takakazu , Kubo Yukihiro , Uenishi Junichi , Oae Shigeru
Published: July 2006

Cross-coupling product 2-(2-pyridyl)quinolines were obtained in the reaction of 2-(methylsulfinyl)quinolines and 2-(methylsulfinyl)pyridines with methylmagnesium bromide. Attempts of cross coupling in the reaction of other substrates were unsuccessful.
Electron Transfer Resulting from Excitation of Contact Charge Transfer Complexes of Some Styrene Derivatives and Oxygen. The Role of Oxygen as an Electron Acceptor
Authors: Kojima Masanobu , Sakuragi Hirochika , Tokumaru Katsumi
Published: July 2006

Irradiation of contact charge transfer (CCT) bands (320–370 nm) of 4-methoxystyrene (1a) and 4-methylstyrene (1b) with molecular oxygen in acetonitrile and benzene resulted in the formation of the corresponding cis- and trans-1,2-diarylcyclobutanes (2 and 3) as well as benzaldehydes (4), oxidative cleavage products. In the case of 1b, 7-methyl-1-(4-tolyl)-1,2,3,4-tetrahydronaphthalene (5) and 6-methyl-4-(4-tolyl)-1,2,3,4-tetrahydronaphthalen-1-one (6) were also afforded. The formation of these products is reasonably explained by electron transfer in the excited CCT pair followed by addition of the resulting 1 cation radical to ground-state 1 to form a dimer cation radical; its cyclization leads to the dimeric products and trapping of a cyclic dimer cation radical by oxygen affords ketone 6.
Synthesis of Bis(deoxyribonucleoside) Phosphoromorpholidate Derivatives for Oligodeoxyribonucleotide Preparation by Use of a Selective Phosphitylating Reagent
Authors: Ozaki Hiroaki , Yamoto Shuhei , Maikuma Seiichirou , Honda Kenichi , Shimidzu Takeo
Published: July 2006

Sequence-defined bis(deoxyribonucleoside) phosphoromorpholidate derivatives as stable intermediates to prepare oligodeoxyribonucleotides have been synthesized using morpholinodi(1-tetrazolyl)phosphine as a phosphitylating reagent. The general procedure is composed of following steps (in situ); a) a reaction of 5′-O-protected deoxyribonucleoside with morpholinodi(1-tetrazolyl)phosphine (phosphitylation), b) a reaction of the resulting 5′-O-protected deoxyribonucleoside phosphorobisamidite with the second deoxyribonucleoside (coupling), and c) a nonaqueous oxidation with t-BuOOH (oxidation). In the coupling step, the 5′-O-protected deoxyribonucleoside phosphorobisamidite was selectively reacted with 5′-OH group of the second deoxyribonucleoside, and therefore, a protection of hydroxyl groups of the second deoxyribonucleoside is not necessary. As the resulting P–N bond in the phosphoramidate linkage after oxidation is stable both in acidic and basic conditions, the morpholino function as a phosphoryl protecting group may have many potential use in the synthetic chemistry of oligonucleotide. A thymidine trimer can be obtained in a high yield by extending the present synthetic method.
Use of Axially Chiral 2′-Methoxy-1,1′-binaphthyl-2-carboxylic Acid as Chiral Derivatizing Agent for Discrimination of Enantiomeric Alcohols and Amines by 1H NMR
Authors: Miyano Sotaro , Okada Shin-ichi , Hotta Hiroki , Takeda Masayuki , Suzuki Takatsugu , Kabuto Chizuko , Yasuhara Fujiko
Published: July 2006

Axially chiral 2′-methoxy-1,1′-binaphthyl-2-carboxylic acid (1) was effectively utilized as chiral derivatizing agent for discrimination of enantiomeric alcohols and amines by 1H NMR with the aid of Eu(fod)3. Among a pair of the diastereomeric esters or amides prepared from (aS)-1 and an α-chiral alcohol or amine, the methoxyl protons of the (aS,R)-diastereomer showed the larger lanthanoid-induced downfield shift than those of the (aS,S)-counterpart. Thus, addition of up to 0.5–1.0 equiv amount of Eu(fod)3 caused base-line separation of those protons, allowing determination of the enantiomeric purities and assignment of the absolute configurations of the enantiomeric alcohols and amines. An X-ray crystallographic analysis of the amide ((aS,S)-2) obtained from (aS)-1 and (S)-1-phenylethylamine showed structural resemblance between the amides and esters of 1. Steric models which explain the NMR behavior of the diastereomeric esters and amides are presented based on X-ray analyses. Also reported are two methods to regenerate free acid 1 from amide 2 to afford axially homochiral 1.
High-Resolution 13C NMR Study of (1→3)-β-d-Glucans in the Solid State: DMSO-Induced Conformational Change and Conformational Characterization by Spin-Relaxation Measurements
Authors: Saitô Hazime , Yokoi Motoko
Published: July 2006

High-resolution 13C NMR spectra of a variety of (1→3)-β-d-glucans were recorded in the solid state after lyophilization from DMSO solution in order to study resulting conformations free from the triple-helix conformation. Lyophilization from DMSO solution caused conformational change of laminaran from Laminaria species (‾Dp=38) from the triple helix to the oligomer-type form (form I). On the contrary, single-chain conformation (form II) of high molecular-weight curdlan was unchanged before and after lyophilization from DMSO solution. Further, DMSO induced conformational change of both single-chain (form II) and triplehelical (form III) conformations of acid-degraded curdlan (‾Dp=14) to the form I. These findings support our view that the single-chain conformation is a major form in curdlan powder. We found that these three forms are distinguished by either the 13C spin-lattice relaxation times (T1C’s) of the laboratory frame or proton spin-lattice relaxation times in the rotating frame (T1ρH). In particular, the form I was distinguishable from others by its prolonged T1C values (3.5–12 s) of C-6 carbon. In addition, the T1ρH of the triple helix of annealed curdlan was one order of magnitude longer than that of the single chain, reflecting their difference in the manner of molecular packing.
Laser Flash Photolysis Study of the Magnetic Field Effects on the Biradicals Generated from Aromatic Ketone-Xanthene Bifunctional Chain Molecules
Authors: Tanimoto Yoshifumi , Takashima Masanobu , Itoh Michiya
Published: July 2006

The external magnetic field effects (MFE) on the biradicals generated from the intramolecular photoreactions of bifunctional chain molecules, α-(xanthone-2-carbonyloxy)-ω-(xanthene-2-carbonyloxy)alkanes (XO-n-XH, n=2–12) and Ar-12-XH (Ar=anthraquinone-4-carbonyloxy (AQ), 4-benzoylphenoxy (BP), and 4-acetylphenoxy (AP)) were studied by laser flash photolysis. All biradicals exhibit significant MFE. The simultaneous observation of the effects on the two radicals at the ends of the chain, generated from XO-12-XH, AQ-12-XH, and BP-12-XH, presents unequivocal evidence that the respective two radical centers correlate magnetically each other. The n dependence of the effects on biradicals generated from XO-n-XH indicates that the singlet–triplet degeneracy of the biradical occurs at the chain length of around n=6, i.e., the interradical distance of about 15 Å.
Optical Resolution of a Co(III) Complex of 2-Hydroxy-1,3-propanediamine-N,N,N′,N′-tetraacetic Acid: Crystal Structure of (+)589-Strychnine (2-Hydroxy-1,3-propanediamine-N,N,N′,N′-tetraacetato)cobaltate(III) Sesquihydrate, (+)589-(STC)[Co(dhpta)]·1.5H2O
Authors: Sato Mitsunobu , Yano Shigenobu
Published: July 2006

The 2-hydroxy-1,3-propanediamine-N,N,N′,N′-tetraacetatocobaltate(III) complex has been optically resolved using strychnine nitrate. The crystal structure of the optically active complex with the resolving agent, (+)589-(STC)[Co(dhpta)]·1.5H2O has been determined from three dimensional X-ray diffraction data. The absolute configuration around the cobalt atom, to which two nitrogen and four oxygen atoms in the ligand are bonded nearly octahedrally, is Δ. The six-membered chelate ring adopts the λ-skew boat conformation. The intermolecular hydrogen bonding between the coordinated oxygen atom of the acetate ring and the protonated nitrogen atom of strychnine, which is one of the asymmetric centers, plays an important role in the diastereomeric discrimination. In contrast, the non-coordinated hydroxyl group in the complex ion does not interact directly with the strychnine molecule. The relationship between the absolute configuration around the cobalt center and the circular dichroism has been examined for the optically active complex ion.
Structures of 1,4,13,16-Tetraoxa-7,10-dithia[16](1,1′)ruthenocenophane and Its 1:2 HgCl2 Complex
Authors: Sato Sadao , Habata Yoichi , Sato Masaru , Akabori Sadatoshi
Published: July 2006

The reaction of 1,1′-bis(6-chloro-1,4-dioxahexyl)ruthenocene with disodium 1,2-ethanedithiolate gave 1,4,13,16-tetraoxa-7,9-dithia[16](1,1′)ruthenocenophane (5) in 63% yield. The reaction of 5 with HgCl2 in acetonitrile gave a 1: 2 complex (6) in 47% yield. The crystal structure of complex 6 and its metal free ligand 5 were determined by an X-ray method. Crystal data: 5, triclinic, a=11.128(2), b=12.720(2), c=10.196(2)Å, α=113.55(1), β=64.13(1), γ=122.01(1)°, U=1074.1 Å3. P\bar1, Z=2, Dc=1.54 Mg m−3, μ(Mo Kα)=9 mm−1. R=0.028. 6, triclinic, a=16.595(4), b=12.645(3), c=7.401(1)Å, α=104.92(1), β=92.37(1), γ=69.38(2)°, U=1402.4Å3, P\bar1, Z=2, Dc=2.46 Mg m−3, μ(Mo Kα)=12.2 mm−1, R=0.081. The X-ray analysis of 6 revealed that one Hg atom was bonded to the Ru atom of the ruthenocene nucleus with a distorted trigonal-planar configuration and another Hg atom was bonded to the two sulfur atoms of the macrocycle. This result is completely different from that obtained regarding complex 4,7,10,13-tetraoxa-1,16-dithia[16](1,1′)ruthenocenophane with HgCl2.
Claisen Rearrangements of 5,6-Dideoxy-1,2-O-isopropylidene-α-d-xylo- and α-d-ribo-hept-5-eno-1,4-furanoses with Triethyl Orthoacetate
Authors: Tadano Kin-ichi , Shimada Kei-ichi , Miyake Akiko , Ishihara Jun , Ogawa Seiichiro
Published: July 2006

The (E)- and (Z)-isomers (2E and 2Z) of 3-O-benzyl-5,6-dideoxy-1,2-O-isopropylidene-α -d-xylo-hept-5-eno-1,4-furanose were subjected to Claisen rearrangement with triethyl orthoacetate. Possible two diastereomers were obtained as a 1 to 1 mixture from both of 2Z and 2E, and also from their 3-hydroxy or 3-siloxy derivatives. On the other hand, the rearrangement of the corresponding d-ribo derivative (13Z) and its 3-O-(t-butyldiphenylsilyl) derivative proceeded with a high level of diastereoselectivity. By contrast, the (E)-isomer of 13Z showed no significant stereoselectivity, resulting in the formation of a diastereomeric mixture. The configurations of the introduced stereogenic centers by the rearrangements were unambiguously established by chemical transformations.
Behavior of the Enthalpy of Mixing in the Ternary Systems Lead–Antimony–Tin, Bismuth–Lead–Tin, and Bismuth–Cadmium–Tin at 950 K. II. Theoretical Aspects
Authors: Badawi Walid Ahmad
Published: July 2006

Analysis of the experimental results which have been obtained from our studies on the ternary systems Pb–Sb–Sn, Bi–Pb–Sn, and Bi–Cd–Sn revealed a new effect: deduction of a straight line obtained by interpolation between the pairs Sb–Pb and Sb–Sn at xPb=xSn=0.5 from the partial enthalpy of mixing of antimony, hSbm, yields a remainder quantity, rhSbm. The minimum of this remainder lies at the section drawing xPb/xSn=1. Further studies on the systems Bi–Pb–Sn and Bi–Cd–Sn indicated that the present “r-effect” is probably a general property of ternary solutions. The sign of the remainder rhim is opposite to that of hm of the pair of components existing vis-a-vis a third apex-component in the same ternary system. Systems of strong heteropolar character which indicate Wagner effect overlapped by III–V one could also exhibit r-effectt. Rules for the mixing behavior in binary systems are in some cases not applicable on the corresponding pairs in the ternary solutions.
Contribution to the Study of the Dielectric Relaxation Process of 1-Iodoalkanes
Authors: Muñoz Embid José , Fornies-Marquina José M\b{a} , Otin Santos
Published: July 2006

A study of the dielectric relaxation process of 1-iodoalkanes (from 1-iodopropane to 1-iodohexadecane) was carried out by measuring their static dielectric constants at 2 MHz and complex dielectric permittivities at 9.23 and 15.05 GHz, in the range of temperature 293.15–343.15 K. The 1-iodoalkanes are classified as belonging to an unsymmetrical distribution of relaxation times of Cole–Davidson type. Activation enthalpies for the relaxation process are obtained by fitting the data of relaxation time as a function of temperature 1to the Eyring equation. The influence of the aliphatic chain length in the 1-iodoalkane on the characteristic parameters of the relaxation process is discussed.
Isomerization in the 1,4,7,10,13,16-Hexaazacyclooctadecanecobalt(III) System [Co(hexacyclen)]3+, and Ion-Association Enhancement of the Unstable Facial Isomer
Authors: Searle Graeme H
Published: July 2006

The substitution reaction [Co(NH3)5(H2O)]3++hexacyclen·3H2SO4+6base+charcoal gives mer-[Co(hexacyclen)]3+ as the major product, and the equilibrium proportion of the fac isomer is <1%. The commercial hexacyclen contains linpen (the open chain analogue of hexacyclen, generated by an elimination reaction in the Richman-Atkins cyclization synthesis procedure), so that the synthesis of complex yields [Co(linpen)]3+ isomers as co-products which complicate the isolation of the pure [Co(hexacyclen)]3+ isomers. Procedures are now given for obtaining the mer and fac isomers pure. In particular, the unstable fac isomer is obtained by isomerization of the mer in base in the presence of the strongly associating anion PO43−. This yields the new equilibrium mixture mer: fac: hydrolysis products=71:18:11, wherein the fac proportion is enhanced twenty times, enabling the pure fac isomer to be obtained in quantity. For the base-catalyzed isomerization reaction fac → mer in NaOH solutions at 50 °C, procedures are given for following the reaction by analyses of samples using ion-exchange HPLC (Na2SO4 elution) and by spectrophotometry. The mechanism must involve intramolecular bond rupture, but the kinetic results are not consistent with a simple SN1CB mechanism, and a two-step process involving an intermediate is indicated.
The Electrocapillary Curves of the Phosphatidylcholine Monolayer at the Polarized Oil–Water Interface. II. Double Layer Structure of Dilauroylphosphatidylcholine Monolayer at the Nitrobenzene–Water Interface
Authors: Kakiuchi Takashi , Nakanishi Masatoshi , Senda Mitsugi
Published: July 2006

Electrocapillary curves have been measured at the polarized nitrobenzene–water interface in the presence of dilauroylphosphatidylcholine (DLPC) in the nitrobenzene phase. DLPC formed a saturated monolayer when the concentration of DLPC was above 10 μmol dm−3. The area occupied by a DLPC molecule in the saturated monolayer was 0.93 nm2, indicating that the monolayer was in the liquid-expanded state. The stability of the monolayer was strongly affected by the electrical potential difference across the interface. The monolayer was stable when the interface was negatively polarized, i.e., the potential in the aqueous phase was negative with respect to that in the oil phase. The potential of zero charge shifted to a negative potential as the adsorption of DLPC increased, which indicated the specific adsorption of lithium ions in the aqueous phase to the head group of the DLPC molecules exposed to the aqueous phase. When the interface was positively polarized, the adsorption of DLPC abruptly decreased and the monolayer appeared to be disrupted.
Synthesis and Characterization of a 3-Thio-2,4-pentanedionate Pt(II) Complex; Bis(dimethylphenylphosphine)[2,4-pentanedione-3-thiolato(2−)-O,S]-platinum(II) Prepared by S–S Bond Cleavage of 2,3-Dithio-1,1,4,4-tetraacetylbutane
Authors: Yamazaki Shinsaku , Ama Tomoharu , Hojo Masashi , Ueno Tamio
Published: July 2006

3-Thio-2,4-pentanedionate (tac) complex of platinum(II), [Pt(tac)(PMe2Ph)2], has been prepared by treating [PtCl(PMe2Ph)3][PF6] with 2,3-dithio-1,1,4,4-tetraacetylbutane in a KOH/methanol–acetone mixed solution. This complex has been characterized by IR, 1H, 13C, and 31P NMR, secondary ion mass and ESR spectroscopy and cyclic voltammetry.
Complexation Reactions of Copper(II) Ions with 16-Membered and 18-Membered Monocyclic Dioxopolyamines in an Aqueous Solution
Authors: Kodama Mutsuo , Anan Hideki , Koike Tohru , Kimura Eiichi
Published: July 2006

The equilibria of complexation reactions of dioxo[16]aneN5, dioxo[18]aneN6, and their related compounds with copper(II) ions were determined potentiometrically. Making a sharp contrast to the 13–15-membered monocyclic dioxotetramine system, they interact with copper(II) ions in their neutral and doubly deprotonated forms, L and H−2L2−, yielding stable CuL2+ and CuH−2L0 complexes.
(2-Pyridylmethoxy)calixarenes: New Versatile Ionophores for Metal Extraction
Authors: Shinkai Seiji , Otsuka Toshio , Araki Koji , Matsuda Tsutomu
Published: July 2006

(2-Pyridylmethoxy)calix[n]arenes (n=6,8) were newly synthesized. It was shown in two-phase solvent extraction that they can extract not only alkali metal cations but Cu2+, Ag+, and UO22+ and are stable even at high pH. The results indicate that disadvantages of calixarene esters, which were previously developed as calixarene-based ionophores, can be improved by using the pyridyl group.
Detailed Dynamic NMR Study of a Molecular Gear, 1-Methoxy-9-(3,5-dimethylbenzyl)triptycene
Authors: Yamamoto Gaku
Published: July 2006

Stereodynamics of the title compound was studied by dynamic NMR spectroscopy. The “isolated” rotation of the aryl group was found to have a lower barrier than the correlated gear rotation.
Syntheses, and Crystal and Molecular Structures of Tetraethylammonium, and Tetrapropylammonium Tris(thiocyanato)cadmates(II), [R4N][Cd(SCN)3], (R=C2H5, C3H7)
Authors: Taniguchi Masahiro , Ouchi Akira
Published: July 2006

The title complexes have been synthesized and their crystal and molecular structures determined by a single crystal X-ray diffraction technique. [(C2H5)4N][Cd(SCN)3] (1) is orthorhombic with a space group of A21am; a=10.773(2), b=16.574(4), c=9.871(2) Å, and Z=4, while [(C3H7)4N][Cd(SCN)3] (2) is triclinic with a space group of P\bar1; a=10.297(5), b=11.542(5), c=9.374(3) Å, α=90.10(3), β=91.61(4), γ=80.94(4)°, and Z=2. In 1, the metal atom has a 3N,3S-hexa-coordinated octahedral geometry, and three ligated N atoms take fac-configuration. Each pair of a metal atoms are bridged by three thiocyanate (SCN) ions, where two SCN ions are S-coordinated, while the other is N-coordinated to the same side metal atom, forming a linear polymeric form. In 2, the metal atom is in a 3N,2S-penta-coordinated trigonal-bipyramidal geometry, where one non-bridging SCN ion is N-coordinated equatorially, while four bridging SCN ions are ligated with two N (axially), and two S atoms (equatorially), respectively. Each pair of metal atoms is bridged by two SCN ions, forming a linear polymeric form. The respective tetraalkylammonium ions in 1 and 2 are not bridged to the complex anions, but are bonded only electrostatically. The final R values obtained are: 1, 0.042 and 2, 0.052.
Halogenation Using Quaternary Ammonium Polyhalides. XIV. Aromatic Bromination and Iodination of Arenes by Use of Benzyltrimethylammonium Polyhalides–Zinc Chloride System
Authors: Kajigaeshi Shoji , Kakinami Takaaki , Moriwaki Masayuki , Tanaka Toshio , Fujisaki Shizuo , Okamoto Tsuyoshi
Published: July 2006

The reaction of arenes with benzyltrimethylammonium tribromide or benzyltrimethylammonium dichloroiodate in acetic acid in the presence of ZnCl2 at room temperature or at 70 °C gave bromo- or iodo-substituted arenes in good yield, respectively.
Reaction of 9-Diazofluorene with 2,3-Dichloro-5,6-dicyano-p-benzoquinone: The Structure and the Behaviors of the Resulting Product
Authors: Shingaki Tadao , Kuma Hiro , Kushi Yoshihiko , Nagai Toshikazu
Published: July 2006

The title reaction gave 3′,4′-dichloro-1′,6′-dicyanospiro[fluorene]-9,7′-[3′]norcarene]-2′,5′-dione (2) in a good yield. Recrystallizations of 2 from solvents such as benzene, dioxane, acetonitrile, and acetone gave each molecular complex consisting of a 2/solvent molar ratio of 1:1. The structure of 2 was determined by the use of one complex, 2·CH3COCH3, by an X-ray crystallographic analysis, which revealed that an interaction between 2 and acetone was not very strong. Such a host–guest interaction was shown also from 1H NMR spectroscopy and a differential thermal analysis of the complex. Compound 2 afforded the corresponding spiroacetals of 9-fluorenone through reactions with ethylene glycol and 1,3-propanediol.
Reversible Bond Switch with Participation of Hypervalent Sulfurane in a Thiadiazole Ring System and Its Kinetic Study in a Protonated System
Authors: Yamamoto Yohsuke , Akiba Kin-ya
Published: July 2006

The existence of ring transformation equilibrium (bond switch) in 5-(1-aminoethylideneamino)-3-methyl-1,2,4-thiadiazole (5a) was confirmed by nitrogen-15 labeling experiment. Kinetic studies were carried out under neutral or acidic conditions. Kinetic parameters of the intramolecular equilibration of the monoprotonated 5a (5a-H+) were obtained by line shape analyses of the 1H NMR, i.e., ΔG273\eweq=14.8±0.2, ΔH\eweq=11.6±1.0 kcal·mol−1 ΔS\eweq=−12±3 eu, k273=9 s−1. Position of protonation was determined at the nitrogen of the ethylideneamino part of the amidino group. It was concluded that the central sulfur atom moves back and forth in the range of 0.38 Å nine times a second at 0 °C, that is, bond switching.
Reactivities of Stable Rotamers. XXV. Deprotonation at the 9-Position of 9-(2-Substituted 1-naphthyl)fluorene Rotamers with Butyllithium
Authors: Moriyama Kazuhiro , Nakamura Mikio , Nakamura Nobuo , Oki Michinori
Published: July 2006

Deprotonation of 9-(2-substituted 1-naphthyl)fluorene rotamers, where the substituent is a dimethylamino, a methoxy, or a methylthio, has been carried out with butyllithium in hexane–benzene. While the reactions of the ap-isomers were generally slower than those of the sp-isomers, the difference in the methoxy compounds was the greatest among the compounds examined. The results are discussed on the basis of the ease of ligation of the substituent and the steric effects that prevail in the ap-isomers, together with the distance between 9-position and the ligation site in the subsituent.
Protease-Catalyzed Peptide Formation under High Pressure
Authors: Kunugi Shigeru , Tanabe Kazuo , Yamashita Kouji , Morikawa Yoshio , Ito Takanobu , Kondoh Toshihiro , Hirata Kouichirou , Nomura Akihiko
Published: July 2006

The effect of high pressure on peptide formation by the catalysis of carboxypeptidase Y (substitution of ester or peptide by amino acid derivative) or by thermolysin (condensation of N-acylamino acid and amino acid amide) was studied. The carboxypeptidase Y-catalyzed substitution reaction of N-[3-(2-furyl)acryloyl]phenylalanine ethyl ester with glycinamide or phenylalaninamide showed a six-fold higher total peptide yield at 200 MPa than at atmospheric pressure. In the case of the reaction of N-acyldipeptide and amino acid amide, both the peptide yield and substitution efficiency were improved at elevated pressure and the wasteful hydrolysis of the substrate was highly depressed by increasing pressure. The pressure was also effective to get rid of the substrate inhibition by the amino acid ester in the reaction between the N-acylamino acid ester and the amino acid ester and to yield much dipeptide ester at high pressure. An improvement of the peptide yield by pressure for the reaction of thermolysin was observed in a combination of less specific substrates, N-benzyloxycarbonyl-l-aspartic acid and phenylalanine methyl ester, since the high catalytic activity of this enzyme under elevated pressure was significant only in the case that the peptide yield was kinetic-controlled.
Cr(III) or Ce(IV) Impregnated Perfluorinated Resin–Sulfonic Acid Catalyst for the Oxidation of Alcohols
Authors: Kanemoto Shigekazu , Saimoto Hiroyuki , Oshima Koichiro , Utimoto Kiitiro , Nozaki Hitosi
Published: July 2006

Several polymer supported catalysts are prepared by treatment of Nafion®551 (abbreviated NAFK below) with metal salts. Cr/NAFK and Ce/NAFK are found to be effective catalysts for the dehydrogenative oxidation of alcohols to the corresponding ketones by means of t-butyl hydroperoxide. Selective oxidation of secondary alcohols in the presence of primary ones was performed using a Ce/NAFK–NaBrO3 system.
Development of a Facile Method for Polypeptide Synthesis. Synthesis of Bovine Pancreatic Trypsin Inhibitor (BPTI)
Authors: Aimoto Saburo , Mizoguchi Noriko , Hojo Hironobu , Yoshimura Shoko
Published: July 2006

A new method for the preparation of pure polypeptides based on the minimun-protection strategy is described. Its effectiveness was demonstrated by a synthesis of bovine pancreatic trypsin inhibitor (BPTI). Protected peptide segments of Z-[Arg(Tos)1, Asp(OcHex)3, Cys(Acm)5, Glu(OcHex)7]-BPTI(1–13), Boc-[Cys(Acm)14,30, Lys(Z)15,26]-BPTI(14–36), and [Cys(Acm)38,51,55, Lys(Z)41,46]-BPTI(37–58) were prepared by modifying the products obtained by solid-phase peptide syntheses. The protected peptides corresponding to BPTI(14–36) and BPTI(37–58) were coupled by an active ester method to give protected BPTI(14–58). Next, protected BPTI(1–13) was coupled to the BPTI(14–58) by an active ester method after removing the Boc group from the protected BPTI(14–58). All of the protecting groups on BPTI(1–58) were removed, and the resulting peptide was oxidized to give the native form of BPTI in a very pure form. The synthetic BPTI was shown to be identical with the native BPTI in an elution experiment on ion-exchange chromatography and in its inhibitory activity. The new method proved to be very effective for a rapid preparation of pure polypeptide.
3,3′-carbonylbis[5-phenyl-1,3,4-oxadiazole-2(3H)-thione]: A Novel, Reactive, and Versatile Condensing Agent for Amide, Ester, Thiol Ester, Urea, Carbonate, Polyamide, and Polyurea Syntheses
Authors: Saegusa Yasuo , Watanabe Tatsushi , Nakamura Shigeo
Published: July 2006

A novel condensing agent, 3,3′-carbonylbis[5-phenyl-1,3,4-oxadiazole-2(3H)-thione] (3), was readily prepared by the reaction of 5-phenyl-1,3,4-oxadiazole-2(3H)-thione with trichloromethyl chloroformate in benzene. The reagent 3 was found to be very useful for the one-pot or direct preparation of amide, ester, thiol ester, urea, and carbonate under mild conditions. The one-pot or direct polycondensation of several dicarboxylic acids with aromatic diamines and of aromatic diamines using 3 proceeded smoothly at ambient temperature to produce high-molecular-weight polyamides and polyureas, respectively.
X-Ray Crystal Structures of trans-(Chloromethyl)bis(2,4-pentanedionato)(aqua and methanol)chromium(III) Completes. Evidence for a Trans Influence Exerted in the Carbon-Bonded Chromium(III) Complexes
Authors: Abe Yoichi , Ogino Hiroshi
Published: July 2006

The crystal and molecular structures of alkylchromium(III) complexes, trans-[Cr(CH2Cl)(acac)2(H2O)]·EtOH and trans-[Cr(CH2Cl)(acac)2(MeOH)] (acac−=2,4-pentanedionate anion, EtOH=ethanol, MeOH=methanol), have been determined by X-ray structure analyses. Both crystals are triclinic and the space group P\bar1; Z=2 with a=9.935(2), b=10.606(2), c=9.399(2) Å, α=90.39(2), β=92.44(2), γ=115.54(1)° for the aqua complex, and Z=4 with a=11.402(6), b=16.780(7), c=8.543(3) Å, α=98.83(3), β=102.00(4), γ=83.03(4)° for the methanol complex. Each complex has trans configuration. The carbon-bonded CH2CI group elongates specifically the Cr–O bond trans to the Cr–C bond in the aqua complex (Cr–O(H2O)=2.134(6) Å) and methanol complex (Cr–O(MeOH)=2.156(6), 2.136(6) Å).
The Thermodynamics of the Micelle Formation of Sodium α,ω-Alkanediyl Disulfate
Authors: Ikeda Kenji , Nakasima Tomoko , Esumi Kunio , Meguro Kenjiro
Published: July 2006

The critical micelle concentrations of a α,ω-type surfactant: (sodium α,ω-alkanediyl disulfate: n=12, 14, 16) in an aqueous solution have been determined by studying the electrical conductivity, and the free energies of the micelle formation have then been estimated from these data. The free energy of micelle formation of a α,ω-type surfactant was smaller than that of a normal-type surfactant with the same alkyl chain length as the α,ω-type one. The free-energy changes per –(CH2)– segment was also calculated from these data. It is found that the free-energy change per –(CH2)–segment of the α,ω-type surfactant is −11.1 [kJ mol−1].
Single Crystals Coimaged with the Gigantic Rod-Like Micelles in Viscoelastic Cationic Surfactant–Aromatic Additive Systems
Authors: Hirata Hirotaka , Sakaiguchi Yuko
Published: July 2006

In a system of hexadecyltrimethylammonium bromide (HTAB)–salicylic acid (SA) in which a remarkable viscoelasticity is induced, we noticed the existence of single crystals coimaged with the infinitely elongated rod-like micelles. The single crystal implied the formation of a new species, a complex which resulted from the interaction of HTAB and aromatic additives.
Cyclization of Penta- and Hexapeptide Active Esters Related to Gramicidin S and Gratisin
Authors: Tamaki Makoto , Takimoto Michiaki , Hayashi Mitsuo , Muramatsu Ichiro
Published: July 2006

Four pentapeptide N-hydroxysuccinimide esters [X–Orn(Z)–Leu–Y–Pro–ONSu (X=Val or d-Val, and Y=Phe or d-Phe)] related to gramicidin S were allowed to cyclize in pyridine. The peptides with a l-Phe residue preceding Pro tend to form various cyclic polymers, while ones with a d-Phe residue exclusively yielded a cyclic monomer or cyclic dimer. Peptides with a d-Val residue at the N-terminal produced monomerization products. The observed tendencies were similar for cyclization of four hexapeptide N-hydroxysuccinimide esters [X–Val–Orn(Z)–Leu–Y–Pro–ONSu (X=Tyr(Bzl) or d-Tyr(BzlCl2), and Y= Phe or d-Phe)] related to gratisin.
Synthesis of (±)-Hernandulcin by an Intramolecular Nitrile Oxide Cycloaddition Route from Farnesol
Authors: Zheng Guo-Chi , Kakisawa Hiroshi
Published: July 2006

An intramolecular addition reaction of the nitrile oxide derived from (2Z, 6E)-farnesal oxime afforded an isoxazoline derivative, which was converted into hernandulcin, a sweet sesquiterpene of Verbenaceae plant.
The Reaction of Arylazo Aryl Sulfones with Carbon Monoxide and Nucleophiles Catalyzed by the Palladium(0) Complex
Authors: Kamigata Nobumasa , Satoh Akira , Yoshida Masato , Kameyama Masayuki
Published: July 2006

The reaction of arylazo aryl sulfone (1) with carbon monoxide in the presence of the palladium(0) catalyst affords substituted benzoic acid in a good yield, together with minor yields of diaryl ketone and biaryl. The reactions of 1 with carbon monoxide and such nucleophiles as alcohols and amines under similar conditions give esters and amides, respectively.
Synthesis of 10-(8-Aminooctyl)flavin and Its Use in Affinity Chromatography
Authors: Kasai Sabu , Nakano Hideko , Maeda Kazuya , Matsui Kunio
Published: July 2006

7,8-Dimethyl-10-(8-aminooctyl)isoalloxazine was synthesized by coupling N-(8-aminooctyl)-4,5-dimethyl-1,2-benzenediamine with alloxan. The flavin was immobilized to epoxy activated gel to use for affinity chromatography. The gel was effective for purification of riboflavinbinding protein from egg white and flavokinase from rat liver.
Formation and Reaction of Oxazoles. Synthesis of N-Substituted 2-(Aminomethyl)oxazoles
Authors: Ibata Toshikazu , Isogami Yasushi
Published: July 2006

The BF3-catalyzed reaction of substituted α-diazoacetophenones with chloroacetonitrile gave 5-aryl-2-chloromethyloxazoles (3) in high yields. Methyl p-nitrophenyldiazoacetate also yielded 2-(chloromethyl)-5-methoxy-4-(p-nitrophenyl)oxazole. The nucleophilic substitution of 3 with primary, secondary, and tertiary amines afforded the corresponding secondary amines, tertiary amines, and quaternary ammonium salts bearing a 2-oxazolylmethyl group.
Reactivities of Stable Rotamers. XXVI. Some Bimolecular Elimination Reactions of 9-(2-Substituted 1-naphthyl)fluorene Rotamers
Authors: Sonoda Yoriko , Tsukahara Jiro , Nakamura Nobuo , Oki Michinori
Published: July 2006

Various elimination reactions which are believed to proceed with E2-type mechanisms have been examined on 9-[2-(1,2-dibromoethyl)-1-naphthyl]fluorene and 9-[2-(1-hydroxy-2-trimethylsilylethyl)-1-naphthyl]fluorene rotamers. Generally, the reaction of the sp rotamers was faster than that of the ap by a factor of 2–9. The results are attributed to the steric effects that are operative in the ap form.
A Total Synthesis of (−)-Sacculatal
Authors: Hagiwara Hisahiro , Uda Hisashi
Published: July 2006

The total synthesis of a tumor promoter, (−)-sacculatal (1), has been completed.
Catalytic Hydrogenation and Cracking of Anthracene over MoCl3–LiCl–KCl and NiCl2–LiCl–KCl Salts
Authors: Song Chunshan , Ono Tomohiro , Nomura Masakatsu
Published: July 2006

The MoCl3– and NiCl2–LiCl–KCl salts, which are effective coal liquefaction catalysts, promoted the hydrogenation of anthracene (at 400 °C for 1 h with 9.8 MPa H2) and afforded tetrahydro- and octahydro- as well as dihydroanthracene as major products. However, these catalysts did not remarkably enhance the ring-opening cracking reactions. A comparative examination suggested that the addition of LiCl–KCl to MoCl3 and NiCl2 suppressed their cracking ability and improved their hydrogenation selectivity.