bluuebunny/crossref_metadata_2025 huggingface dataset:
Raman Spectra in the Skeletal Vibration Region of [Co(gly)x(ox)y(en)z](3−x−2y)+ Complexes (x+y+z=3)
Authors: Maruyama Toshihide F , Okamoto Ken-ichi , Hidaka Jinsai , Einaga Hisahiko
Published: July 2006

The Raman spectra were measured for the complete series of cobalt(III) complexes, [Co(gly)x(ox)y-(en)z](3−x−2y)+, where gly, ox, and en denote glycinate, oxalate, and ethylenediamine, respectively, and x+y+z is equal to 3, in aqueous solution in the skeletal vibration region to deduce their structure-spectra relation. The spectra could be classified into four categories: polarized bands in the 610–520 cm−1 region due to a totally symmetric stretching vibration mode, depolarized bands in the 520–400 cm−1 region due to Co–O and Co–N stretching vibration modes, depolarized bands in the 400–300 cm−1 region due to the metal-ligand skeletal bending deformation mode, and polarized bands in the 300–200 cm−1 region due to the chelate ring deformation mode. The depolarized bands due to the stretching vibration mode could be used for the differentiation of C2-cis and C1-cis isomers of [Co(N)4(O)2] and [Co(N)2(O)4] type complexes.
The Formation of Tetrasulfur Dinitride during the Mild Pyrolysis of Tetrasulfur Tetranitride
Authors: Kudo Yoshiyuki , Hamada Shuichi
Published: July 2006

Tetrasulfur dinitride was formed by the mild pyrolysis of tetrasulfur tetranitride in the presence of a large amount of sulfur. The stoichiometric correlations of the pyrolytic products indicated a step-by-step degradation of the tetrasulfur tetranitride. Differential scanning calorimetry of an interrupted pyrolysis and determinations of the products gave the enthalpy of the formation of gaseous tetrasulfur dinitride as 351±3 kJ mol−1, which was reasonable judging from the bond enengies calculated by Sanderson’s method and those deduced from known bond energies. The obtained standard enthalpy of the formation of tetrasulfur tetranitride was 469±1 kJ mol−1, which agreed with the value reported by Barker et al.
The Ruthenium Catalyzed N-Alkylation of Amides with Alcohols
Authors: Watanabe Yoshihisa , Ohta Tetsuo , Tsuji Yasushi
Published: July 2006

Amides reacted with primary alcohols in the presence of a catalytic amount of RuCl2(PPh3)3 at 180 °C to give the corresponding N-monoalkyl amides in fairly good yields. Thus, benzamide reacted with 1-octanol to give N-octylbenzamide in 76% yield with excellent product selectivity. Little esterification of amides with alcohols occurred and selectivity to the N-alkylation was high. Most of the amides gave N-monoalkyl amides but no N,N-dialkyl amides. But formamide reacted with 1-butanol to give N,N-dibutylformamide, as well as N-butylformamide, in low yield. RuCl2(PPh3)3 was the most effective catalyst for this reaction and RuHCl(PPh3)3 also had some catalytic activity.
Cobalt(III) Complexes with Quadridentate Ligands. IV. The Preparation and Properties of “cis-β1 and β2” Isomers of the 2-Methyl-8-quinolinolato(triethylenetetramine)-cobalt(III) and Related Complexes
Authors: Yamamoto Yoshihisa , Toyota Eiko , Yamamoto Yutaka
Published: July 2006

cis-β1- and β2-8-Quinolinolato or 2-methyl-8-quinolinolato(triethylenetetramine)cobalt(III) complexes, (Remark: Graphics omitted.) (R: H, Me; X: Cl, NO3), have been isolated from a reaction mixture of cis-α-dichloro(triethylenetetramine)cobalt(III) chloride, Ag2O, and 8-quinolinol or 2-methyl-8-quinolinol. The separation of their cis-β and β2 isomers was achieved by the use of ion-exchange resin. The IR spectra of these complexes showed five or six absorption bands in the 990–1100 cm−1 region and four or five absorption bands in the 3000–3300 cm−1 region. This indicates that these complexes assume the β form. In cis-β1-2-methyl-8-quinolinolato(triethylenetetramine)cobalt(III) complexes, the methyl group of the coordinated 2-methyl-8-quinolinolato ligand has a steric hindrance for the NH-side methylene protons of the coordinated trien ligand. On the other hand, no methyl group of the corresponding cis-β2 form has steric hindrance for the methylene protons of the coordinated trien ligand. Therefore, the distinction of the cis-β1 form and the β2 form of these complexes has been clarified on the basis of their 1H NMR spectra. Also, the 13C NMR spectra of these complexes have shown two different configurations of the “cis-β1 and β2” forms.
Electrochemical Reduction of Some Tris(β-diketonato)ruthenium(III) Complexes in Acetonitrile and Interaction of the Reduced Anions with Lithium and Sodium Ions
Authors: Endo Akira
Published: July 2006

In tetraethylammonium perchlorate–acetonitrile solution, [Ru(R1–CO–CR2–CO–R3)3] (R1,R3=–CH3, –CF3, –C6H5, –C(CH3)3; R2=–H, –C6H5) was reversibly reduced at a dropping mercury electrode to the corresponding univalent anion. A linear relationship was found between the half-wave potential and the sum of the Hammett constants of the substituents of ligands. In some cases, the polarogram and the cyclic voltammogram were shifted to more positive potentials in the presence of lithium or sodium ions. This effect was explained quantitatively by the two-step association between the reduction product, [Ru(R1–CO–CR2–CO–R3)3]−, and alkali metal ions. The association constants were calculated. The K2 values were appreciable and the K1 values were much larger than expected for a simple electrostatic interaction. Furthermore, the K1 values were linearly related to the sum of the Hammett constants of the substituents of the ligands. These results suggest the importance of the local charge distribution on the complex anions. In the presence of lithium ion, [Ru(acac)3]− forms Li[Ru(acac)3] which is insoluble in acetonirile.
Reactive Troponoids and o-Aminophenol. V. The Reaction of 3-Bromo-2-methoxytropone and o-Aminophenol
Authors: Someya Taichi , Okai Harue , Wakabayashi Hidetsugu , Nozoe Tetsuo
Published: July 2006

The reaction products of the title substances in hot acetic acid were separated by preparative TLC into compounds A–L according to the Rf-values, and the structural assignments for these products were now made as follows: A, 14H-[1,4]benzoxazino[3′,2′ : 3,4]cyclohepta[1,2-b][1,4]benzoxazine; B, 1-formylphenoxazine; F, cyclohepta[2,1-b : 2,3-b′]di[1,4]benzoxazine; G, cyclohepta[b][1,4]benzoxazin-10(11H)-one or its enolic form; J, cyclohepta[b][1,4]benzoxazin-6(11H)-one; L, 6-(o-hydroxyanilino)cyclohepta[b][1,4]benzoxazine hydrobromide. A small amount of 2-methylamino-3H-phenoxazin-3-one was also produced. Possible reaction pathways for the formation of these products are also discussed.
Cyclotrimerization and Polymerization of 1-Hexyne Catalyzed by Group 5, 6 Transition Metal Chlorides
Authors: Masuda Toshio , Deng Yun-Xiang , Higashimura Toshinobu
Published: July 2006

1-Hexyne could be cyclotrimerized selectively and quantitatively by NbCl5 and TaCl5. The cyclotrimer formed consisted of 1,2,4- and 1,3,5-isomers. The 1,2,4/1,3,5 isomer ratio of the product was about 70/30–80/20 with NbCl5, and about 55/45–70/30 with TaCl5. The polymerization of 1-hexyne by MoCl5- and WCl6-based catalysts afforded a methanol-insoluble polymer and methanol-soluble products in comparable amounts. The polymer (mol wt 3000–5000) was an orange-yellow viscous material with structure [ \llap–CH=C(n-Bu)  \llap–]n. For comparison, the cyclotrimerization and polymerization using Ziegler catalysts were also examined.
N-Alkylation of Pyrrole, Indole, and Several Other Nitrogen Heterocycles Using Potassium Hydroxide as a Base in the Presence of Polyethylene Glycols or Their Dialkyl Ethers
Authors: Sukata Kazuaki
Published: July 2006

The alkylation of pyrrole and indole in aqueous potassium hydroxide-organic two-phase systems in the presence of polyethylene glycols (PEG) or their dialkyl ethers (PEG-ether) as phase transfer catalysts (PTC) gave substantial quantities of the C-alkylated and C,N-polyalkylated products as well as the N-alkylated products. This fact is similar to that obtained in the presence of quaternary ammonium salts as PTC. In powdered potassium hydroxide-organic two-phase systems, the yields of the N-alkylated products were generally high. Especially, when PEG-ether were employed as solvents, the N-alkylated products were obtained in excellent yields under mild conditions. Imidazole, benzimidazole, carbazole, 2-methylindole, and benzotriazole were similarly N-alkylated in high yields by this method.
Assignment of a Characteristic Infrared Absorption Band at 810 cm−1 in Heat-treated Polyacrylonitrile
Authors: Okamoto Masao
Published: July 2006

When polyacrylonitrile (PAN) was heat-treated at about 250 °C under nitrogen, a violent exothermic reaction took place. PAN lost weight and the infrared absorption at 2240 cm−1 disappeared, but there was little change in the atomic ratios of carbon, hydrogen, and nitrogen. This indicates that fragmentation is accompanied by rapid polymerization of cyano groups. The sample obtained after the completion of the exothermic reaction seems to be liable to oxidation, because a strong exothermic reaction and weight gain occur immediately if air is admitted to enter. During the oxidation the percentages of carbon and nitrogen did not change, but that of hydrogen largely decreased, indicating the occurrence of oxidation and subsequent dehydration in the moieties subjected to polymerization of cyano groups. Therefore, the tri-substituted carbon-carbon double bonds are formed in the six-membered ring systems. A new infrared absorption band which appears at 810 cm−1 is assigned to the C–H out-of-plane bending vibration in such a double bond.
The Dissolution of Heat-treated Acenaphthylene Pitch
Authors: Yamada Yoshio , Shiraishi Minoru , Furuta Takeshi , Yamakawa Toshio
Published: July 2006

About half of the pyridine insolubles in heat-treated acenaphthylene pitch was dissolved into hydrogenated pitch. Observation with optical and scanning electron microscopes showed that the components dissolved consisted of small mesophase spherules with an optically isotropic texture.
Partial Benzylation of Methyl α- and β-d-Galactopyranosides
Authors: Morishima Naohiko , Koto Shinkiti , Oshima Megumi , Sugimoto Akiko , Zen Shonosuke
Published: July 2006

Partial benzylation of methyl α-d-galactopyranoside with benzyl chloride and LiOH selectively gave the 2,3,6-tribenzyl ether, while that using KOH or RbOH gave the 2,4,6-isomer as the main product. Methyl β-d-galactopyranoside afforded the 3,4,6-tribenzyl ether predominantly, irrespective of the alkali used.
Convenient Preparation of Tetraarylphosphonium Halides
Authors: Migita Toshihiko , Nagai Tohru , Kiuchi Kazuhiko , Kosugi Masanori
Published: July 2006

Tetraarylphosphonium halides, particularly iodides, can be conveniently prepared by the Pd-catalyzed reaction of aryl halides and triarylphosphines in good yields.
Free Energy, Enthalpy, and Entropy Changes of Mixing of Aqueous Solutions of d-Glucose and Tetraalkylammonium Bromide at 25 °C
Authors: Miyajima Koichiro , Sawada Masahiro , Nakagaki Masayuki
Published: July 2006

Changes of free energy and enthalpy of mixing of aqueous solutions of d-glucose and tetraalkylammonium bromide were measured at 25 °C by isopiestic method and calorimetry, and excess thermodynamic quantities and transfer functions were calculated. All transfer functions were positive and mutual salting-out was observed. The positive value of free energy of transfer of tetrabutylammoniun bromide from water to aqueous d-glucose solution comes from the predominance of enthalpic term over entropic term. These results are interpreted in terms of the structural incompatibility of hydration cospheres around these two kinds of solutes.
The Effect of Surfactant on Formation of Calcium Carbonate
Authors: Suhara Tsuneo , Esumi Kunio , Meguro Kenjiro
Published: July 2006

Calcium carbonate was precipitated by rapidly mixing calcium chloride solution, sodium carbonate solution, and aqueous surfactant solution at 25 °C in order to elucidate the effect of addition of surfactant on the formation. The samples obtained were examined by scanning electron microscopy, X-ray powder diffraction, and a specific surface area study. The sample without surfactant proved to be calcite crystals. When a cationic surfactant was added, the crystal structure was transferred from calcite and vaterite to calcite with an increase of the concentration of the cationic surfactant. On the other hand, the addition of a lower concentration of an anionic surfactant provided a mixture of calcite and vaterite, but in higher concentration, amorphous material was obtained. The samples with nonionic surfactant were vaterite crystals. It was found that the spherical particle ratio (Nsp) and the vaterite crystal ratio (Fv) in the sample depend on the concentration of the nonionic surfactant.
The Preparation and X-Ray Structures of Di-μ-sulfido- and μ-Oxo-μ-sulfido-bis[tris(isothiocyanato)oxomolybdate(V)] Ions
Authors: Shibahara Takashi , Kuroya Hisao , Matsumoto Keiji , Ooi Shun’ichiro
Published: July 2006

The crystal structures of (pyH)4[Mo2O2S2(NCS)6] (1) (pyH=pyridinium ion) and (pyH)4[Mo2O3S(NCS)6]·2H2O (2) have been determined from the diffractometer data. The 1 and 2 structures were refined by the least-squares method to R 0.041 and 0.064 for 2728 and 2349 non-zero reflections respectively. The two structures are isomorphous. Each Mo(V) ion has a distorted octahedral coordination, and two coordination octahedra share a common edge to form a binuclear complex. The binuclear complex contains a mirror plane through two bridging atoms. The two terminal oxo ligands on each Mo(V) are cis to each other and cis to the bridging oxo or sulfido. The Mo–N(NCS) bond length trans to the Mo–Ot (terminal oxo) is ca. 0.1 Å longer than the other Mo–N(NCS) bond lengths, showing the large trans effect of the Ot ligand.
Preparation, Racemization, and Deuteration of 2-(Methylthio)propionato-S,O and 2-Sulfinatopropionato-S,O Complexes of Cobalt(III)
Authors: Kojima Masaaki , Fujita Junnosuke
Published: July 2006

(+)589-[Co{SCH(CH3)COO}(tren)]+, (−)589-[Co{CH3SCH(CH3)COO}(tren)]2+, and (+)589-[Co{S(O)2CH(CH3)COO}(tren)]+ (tren=tris(2-aminoethyl)amine) were prepared and assigned to the trans(tertiary amine nitrogen, S) isomer with the R carbon atom on the basis of the absorption, CD, and 1H NMR spectra. Racemization of the complexes was studied in aqueous solutions with ionic strength of 0.1, 0.2, or 1.0 (NaClO4) in the pH and temperature ranges of 5.96–6.86 and 19.9–49.5 °C, respectively. The CH3SCH(CH3)COO− and −O2SCH(CH3)COO− complexes follow the rate law, R=kr[OH−][complex]. The second-order rate constants (kr) for the former and the latter complexes are 4.6×103 (35.3 °C) and 7.8×103 (35.2 °C) mol−1 dm3s−1, respectively. The −SCH(CH3)COO− complex did not racemize under these conditions. Deuteration of the methine protons in the complexes was found to proceed simultaneously with the racemization. The differences in reactivity to racemization and proton exchange among three complexes were accounted for by the difference in electron-withdrawing effect of the −S–, S(CH3)–, and −S(O)2– groups, and by the difference in net charge of the complex ions.
Immunoassay Using a Metal-complex Compound as a Chemiluminescent Catalyst. II. An Improvement of the Analytical Method for Practical Use
Authors: Hara Tadashi , Toriyama Motohiro , Tsukagoshi Kazuhiko
Published: July 2006

Immunoassay using a synthesized metal-complex compound as a labeling reagent has been investigated. Iron(III) 2,9,16,23-tetrakis(chlorocarbonyl)phthalocyanine, which showed a marked catalytic action in the chemiluminescence reaction between luminol and H2O2, was synthesized, and albumin was labeled with it. Albumin in the range from 50 ng/tube to 50 μg/tube could be determined by measuring the chemiluminescence intensity in a competitive immunoassay using glass beads immobilized with an antibody. The present method became about 40 time as sensitive as the previous method by optimizing the labeling procedure, the chemiluminescence reaction, and the immune reaction.
Studies on the β-Turn of Peptides. V. Turn Preference of Peptide Sequence Analyzed by Conformational Energy Calculation on Dipeptide Models and by CD Spectra of Chromophoric Derivatives
Authors: Kawai Masao , Sato Kazuki , Sugawara Rika , Nagai Ukon
Published: July 2006

Empirical conformational energy calculations were performed on Ac–l-Pro–d-Ala–NHCH3 and Ac–d-Ala–l-Pro–NHCH3. In order to study the turn tendency of the dipeptide sequences turn probabilities and average interterminal distances were calculated. Much larger turn preference of d-Ala containing sequences was indicated compared with the corresponding l-Ala containing sequences. The turn tendency of the dipeptide sequences were shown to be in the order: l-Pro–d-Ala>d-Ala–l-Pro>l-Pro–l-Ala>l-Ala–l-Pro. This order coincides with the order of the magnitude of the Cotton effects in the CD spectra of the chromophoric derivatives having 2,4-dinitrophenylglycyl and glycine-p-nitroanilide at the N- and the C-termini, respectively, of the corresponding dipeptid esequences. This agreement supports the validity of the chiroptical method to study the turn tendency of the peptide sequences using chromophoric derivatives reported earlier.
A Novel Cyclization Reaction of Alkylthiodiphenylcyclopropenium Ions with Acyclic 1,3-Diketones to Give Cyclopentadienols
Authors: Yoshida Hiroshi , Nakajima Mikito , Ogata Tsuyoshi , Matsumoto Kiyoshi , Acheson R Morrin , Wallis John D
Published: July 2006

Reaction of methylthio-, ethylthio-, and benzylthiodiphenylcyclopropenium salts with 2,4-pentanedione (3a) and ethyl acetoacetate (3b) yielded the cyclopentadienol derivatives (4) by ring expansion. One of the products 4a was shown to be 4-acetyl-5-hydroxy-5-methyl-1-methylthio-2,3-diphenyl-1,3-cyclopentadiene by X-ray crystallography. Chemical transformation of the products yielded some cyclopentenones. Triphenylcyclopropenium perchlorate reacted with 3a and 3b affording the ketocyclopropene in good yields.
Restricted Rotation Involving the Tetrahedral Carbon. XLIV. Atropisomers of 2,3-Dichloro-9-(1-hydroxy-1-methylethyl)triptycene and Related Compounds
Authors: Oki Michinori , Tanaka Yoshiyuki , Yamamoto Gaku , Nakamura Nobuo
Published: July 2006

Atropisomers of 2,3-dichloro-9-(1-hydroxy-1-methylethyl)triptycene were obtained as stable compounds at room temperature. The barrier to rotation (±sc→ap) was 34.0 kcal/mol at 153 °C. Other 9-(1-hydroxy-1-methylethyl)triptycenes carrying a substituent in the 1-position of the skeleton gave ±sc isomers only. Attempted isomerization of the ±sc forms failed because the free energy difference between the ±sc and ap forms is great due to the steric effect. ±sc-9-(1-Methoxy-1-methylethyl)-1,4-dimethyltriptycene was prepared in a hope that increasing the steric size of the hydroxyl group would help to produce an ap-isomer on heating. The ap isomer was detected but the population ratio ap⁄±sc was too small to isolate the ap.
Restricted Rotation Involving the Tetrahedral Carbon. L. Rotamer Distributions and Rotational Barriers in Some 9-(1-Methoxyethyl)triptycene Derivatives
Authors: Tanaka Yoshiyuki , Yamamoto Gaku , Oki Michinori
Published: July 2006

1,4-Dimethyl-and 1,2,3,4-tetrahalo-9-(1-methoxyethyl)triptycenes (halogen=F, Cl, and Br) were synthesized by reactions of 9-(1-methoxyethyl)anthracene with appropriate benzynes. Rotamer distributions and rotational barriers about the bridgehead-to-substituent bond were studied by NMR spectroscopy. Rotamer distributions are governed mainly by the steric effect; the major rotamer is assigned to sc*(S*), the minor one to ap, and the third one found only in the tetrafluoro derivative to sc*(R*). Rotational barriers are 21–23 kcal mol−1 which are slightly lower than those for the corresponding 9-isopropyltriptycenes.
Restricted Rotation Involving the Tetrahedral Carbon. LI. Electrostatic and Hydrogen Bonding Effects on the Rotamer Distribution in 1-Oxy-substituted 9-(1-Methoxyethyl)triptycenes
Authors: Yamamoto Gaku , Tanaka Yoshiyuki , Oki Michinori
Published: July 2006

1-Hydroxy-4-methoxy- (5) and 1,4-dimethoxy-9-(1-methoxyethyl)triptycenes (6) were obtained by the reaction of 9-(1-methoxyethyl)anthracene with p-benzoquinone followed by enolization and methylation. Rotamer equilibrium in 6 is principally governed by the electrostatic effects favoring the ap rotamer. In weakly proton-accepting chloroform-d, 5 exists as sc*(R*) and sc*(S*) rotamers with the former predominating, both of which contain a strong intramolecular hydrogen bonding between the 1-hydroxyl and the methoxyl group in the 9-substituent. In strongly proton-accepting dimethyl-d6 sulfoxide, all the three rotamers exist with the ap rotamer predominating. It is noteworthy that the sc*(R*) rotamer, which is present in 20% ratio in dimethyl sulfoxide, still retains the intramolecular hydrogen bonding in this solvent.
Synthesis and the Spectral Analysis of 4- and 6-[1-Acetamido-3-(3,4,5-trimethoxyphenyl)propyl]-2-methoxytropones(B-Ring-open Analogues of Colchicine)
Authors: Yamamoto Hiroshi , Hara Atsushi , Inokawa Saburo , Nozoe Tetsuo
Published: July 2006

The treatment of 4-[1-acetamido-3-(3,4,5-trimethoxyphenyl)propyl]tropolone with ethereal diazomethane gave the 6- and 4-substituted title compounds in 51 and 38% yields, respectively. The 270-MHz 1H-NMR spectral analysis performed on these compounds, colchicine, and two methyl ethers of hinokitiol permits unequivocal assignment of the position of the C-substituent on these 2-methoxytropone rings. Attempts were made to effect the direct B-ring closure of these intermediates and 4-[1-acetamido-3-(3,4,5-trimethoxyphenyl)propyl]-5-aminotropolone using various oxidizing reagents.
Carbon-13 Relaxation Times of Poly(vinylnaphthalene)s in Solution
Authors: Seki Kazuhiko , Imamura Yoshio
Published: July 2006

Carbon-13 spin-lattice relaxation times and nuclear Overhauser enhancement factors were measured at 25.03 MHz and 40 °C for a solution of poly(1-vinylnaphthalene)(P1VN) and poly(2-vinylnaphthalene)(P2VN). The backbone motions in P1VN and P2VN were characterized by a distribution of correlation times. The relative mobilities of P1VN, P2VN, and polystyrene were as follows: \barτpolystyrene<\barτP2VN<\barτP1VN for the average correlation times. These results were explained on the basis of the energy contour maps for polystyrene, P2VN, and P1VN.
Extractive Spectrophotometric Determinaton of Molybdenum(VI) with 8-Hydroxy-5-quinolinesulfonic Acid and Methyltrioctylammonium Chloride
Authors: Sugawara Masao , Uto Masayuki , Kambara Tomihito
Published: July 2006

Molybdenum(VI) complex with 8-hydroxy-5-quinolinesulfonic acid (H2qs) is reduced to the quinquevalent state by hydrazinium sulfate and extracted into chloroform as the ion-association complex with methyltrioctylammonium chloride(Q+Cl−). Molybdenum(VI) in the ppm range is determined spectrophotometrically. The composition of the extracted species was estimated to be [(MoO2qs)2(Hqs)3(Q)5].
Fluorescence as a Means for Kinetic Studies. III. Bimolecular Reaction of Fluorescent Reagent as Quenching Probes
Authors: Ushiki Hideharu , Okamoto Akio , Horie Kazuyuki , Mita Itaru
Published: July 2006

In order to study the rate of bimolecula reaction between 9-(3-aminopropyl)carbazole and dansyl chloride, the change of fluorescent intensity of dansyl group has been measured. It has been found that the rate of increase in fluorescent intensity of the dansyl group is equal to the rate of decrease in fluorescent intensity of the carbazolyl group during progress of this bimolecular reaction. Another quenching probe was also examined briefly.
Stereoselective Cross-Aldol Reactions of Silyl Enol Ethers with Acetals Catalyzed by Iodotrimethylsilane
Authors: Sakurai Hideki , Sasaki Koshi , Hosomi Akira
Published: July 2006

Iodotrimethylsilane catalyzes effectively erythroselective aldol type condensation of silyl enol ethers with acetals.
Reactivity of Aromatic o-Hydroxy Oximes. II. The Use of Esters of Aromatic o-Hydroxy Oximes in Peptide Synthesis
Authors: Hayashi Ikuo , Shimizu Kiyoshi
Published: July 2006

Esters of N-protected amino acids with o-hydroxybenzaldehyde oxime, o-hydroxyacetophenone oxime, o-hydroxybenzophenone oxime, and their 5-Cl and 5-NO2 derivatives were prepared by several methods. Various dipeptide derivatives with high purity were obtained in good yield by use of these active ester reagents.
Light-induced Redox Characteristics of [Tetrakis(4-methylpyridyl)porphyrinato]manganese(III)
Authors: Takahashi Koushin , Komura Teruhisa , Imanaga Hiroto
Published: July 2006

[Tetrakis(4-methylpyridyl)porphyrinato]manganese(III) (MnIII(tmpp)) undergoes reversible one-electron transfer reactions in aqueous solutions. The half-wave potential of MnIII/II(tmpp) redox couple is −0.21V (vs. 3.33 M KCl, AgCl/Ag) between pH 4 and 12. On the other hand, the half-wave potential of MnIV/III(tmpp) redox couple becomes less positive with increasing pH in alkaline solution. A small amount of methylviologen cation radical (MV.+) is built up by irradiating with visible light an alkaline solution containing MnIII(tmpp), methylviologen (MV2+), and sacrificial electron donors. The formation of MV.+ is attributed to either the reduction of photoexcited MnIII(tmpp) (*MnIII(tmpp)) with an electron donor or the oxidation of *MnIII(tmpp) with MV2+.
A Further ESR Study of Irradiated D2O Ice. On the Nature of the Species Appeared at g=2.08
Authors: Hase Hirotomo , Higashimura Takenobu
Published: July 2006

For D2O ice warmed at ca. 120 K after the irradiation at 77 K, “g=2.08 line” was isolatedly detected at 4 K. The intensity of the line increased for the sample containing an electron scavenger. Photobleaching of solvated electrons caused no change in the intensity of the line. In D2O single crystal, angular dependency of the line was not observed. The overall results were not accomodated to the hypothesis that “g=2.08 line” was due to O− radical, but rather indicated the possibility that the species is a sort of positive ion or trapped hole.
Mössbauer Studies of Mercury(II) Salt Adducts of [2]Ferrocenophane Derivatives
Authors: Watanabe Masanobu , Ichikawa Hajime , Motoyama Izumi , Sano Hirotoshi
Published: July 2006

Various adducts of mercuric salts with [2]ferrocenophane and 1,1,2,2-tetramethyl[2]ferrocenophane, were prepared by treating HgX2 (X=Cl−, I−, CN−) with the [2]ferrocenophane derivatives in ether. The adducts were studied by Mössbauer spectroscopy and other physicochemical measurements. Anomalously large quad-rupole splitting values of the adducts (about 3.10–3.30 mm s−1 at 78 K) suggest the presence of a strong direct interaction between the Fe and Hg atoms.
Selective α-Monoalkylation of Phenylacetonitrile Using Alkali Metal Hydroxide Impregnated on Alumina
Authors: Sukata Kazuaki
Published: July 2006

In the alkylation of phenylacetonitrile with alkyl halides, alkali metal hydroxides impregnated on alumina act as efficient bases for selective α-monoalkylation in benzene. It is proposed that the reaction may take place exclusively in the pore. The selectivity for α-monoalkylation is explained in terms of steric hindrance.
Zeta Potentials of Metal Oxide Surfaces Modified with Silane Coupling Agents
Authors: Esumi Kunio , Meguro Kenjiro
Published: July 2006

The zeta potentials of metal oxide surfaces modified with silane coupling agents were measured as a function of pH in the suspensions. The methylations of the samples by methyltrimethoxysilane showed lower zeta potential values than those of the samples untreated. On the other hand, the treatment of the samples by two different amino silanes rendered the surfaces more cationic. The stability of the deposited silane layers was low; such a layer was easily removed from alumina and anatase-type titanium dioxide.
Studies on the β-Turn of Peptides. VII. Syntheses and Antibiotic Activities of Gramicidin S Analogs with l-Pro-l-Asn or l-Pro-d-Ala Sequence at the β-Turn Part
Authors: Sato Kazuki , Nagai Ukon
Published: July 2006

Two analogs of gramicidin S (GS), [l-Pro4,4′, l-Asn5,5′]-GS (10a) and [l-Pro4,4′, d-Ala5,5′]-GS were synthesized to investigate the possibility of replacing the β-turn part of GS by a different type of β-turn keeping the biological activity. For the synthesis of 10a, three procedures were examined and satisfactory results were obtained by the active ester method applied to cyclization of linear decapeptide with l-Pro at the C-terminus. Neither analog showed antibiotic activity indicating that the β-turn part of GS could not be replaced with l-Pro-l-Asn or l-Pro-d-Ala sequences without affecting on its activity. The CD and ORD spectra of the analogs and their 2,4-dinitrophenyl derivatives showed weaker Cotton effects than those of GS and its derivative, respectively. So, the analogs were considered not to take GS-like β-sheet conformation. The reason why the analogs did not take such conformations was investigated by the model tetrapeptides with chromophoric substituents.
Fluorescence as a Means for Kinetic Studies. II. Preparation and Reactions of Bifunctional Fluorescent Reagents as Kinetic Probes
Authors: Okamoto Akio , Toyoshima Kumiko , Mita Itaru
Published: July 2006

1,5-Naphthalenedisulfonyl dichloride was found to be useful as a bifunctional fluorescent probe for kinetic studies. Its reaction with butylamine in chloroform proceeds stepwise. The first reaction produces a nonfluorescent monosulfonamide and the second slow process forms a fluorescent disulfamide. Their rate constants were obtained. Another bifonunctional fluorescent probe was also examined briefly.
The Platinum Complex Catalyzed Reductive N-Carbonylation of Nitroarenes to the Carbamates
Authors: Watanabe Yoshihisa , Tsuji Yasushi , Takeuchi Ryo , Suzuki Naoki
Published: July 2006

The platium catalyst combined with triphenylphosphine, tin(IV) chloride, and triethylamine showed high activity for the reductive N-carbonylation of nitroarene in ethanol at 180 °C under carbon monoxide of 60 kg cm−2. From nitrobenzene, ethyl phenylcarbamate was obtained in 83% yield. Iron(III) chloride, aluminum chloride and titanium(IV) chloride could be used as Lewis acids in place of tin(IV) chloride. Various nitroarenes were transformed into corresponding carbamate in moderate to excellent yields with the platinum catalyst.
Mechanism of Quenching of SO2 \~{C}(1B2) by He, Ar, and N2
Authors: Oka Takefumi
Published: July 2006

Sulfur dioxide gas was excited to \~{C}(1B2) state by steady illumination and the total intensity and the spectrum of the fluorescence were measured in the SO2 pressure range of 0.1–1 Torr (1 Torr≈133.322 Pa) both in the absence and in the presence of He, Ar, and N2 up to 600 Torr. The observed fluorescence spectrum was broad but the wavelength of the maximum intensity was found to be dependent upon excitation wavelength in the range of 240–220 nm. Addition of foreign gases caused the blue shift of the fluorescence spectrum. The Stern-Volmer plots were nonlinear for quenching by the foreign gases but linear for self-quenching. It was suggested that the foreign gas molecules cause not only vibrational deactivation but also collision induced transition between 1B2 state and a nonemitting state and that the rate constants of the transition to the nonemitting state are larger from higher vibrational levels than from lower ones.
Structure of Liquid N,N-Dimethylformamide Studied by Means of X-Ray Diffraction
Authors: Ohtaki Hitoshi , Itoh Sumiko , Yamaguchi Toshio , Ishiguro Shin-ichi , Rode B M
Published: July 2006

The structure of N,N-dimethylformamide (DMF) was determined at 25 °C by means of X-ray diffraction using a θ-θ type X-ray diffractometer. The least-squares analysis of the reduced intensities results that a DMF molecule has a practically planar skeletal structure in the liquid state. Intramolecular structural parameters within a DMF molecule were determined as follows: C=O; 1.24 Å, N–C(CHO); 1.35 Å, and N–C(CH3); 1.45 Å. The bond lengths are not appreciably different from those found in the gas phase, except for the C=O length, which is slightly longer by 0.04 Å in the liquid state than in the gaseous one. The radial distribution curve of DMF shows that the intermolecular arrangement of DMF molecules is practically fully disordered and no evidence has been found for the cluster formation of DMF molecules in the liquid state. The experimental result for the weak intermolecular interactions between DMF molecules is supported by ab initio MO-SCF calculations.
Microwave Spectroscopy of Boron Chloride (BCl). The Chlorine Nuclear Quadrupole Coupling Constant
Authors: Endo Yasuki , Saito Shuji , Hirota Eizi
Published: July 2006

The pure rotational spectrum of an unstable diatomic molecule, boron chloride (BCl), has been observed in the millimeter wave region. The BCl molecule was directly generated in a 3.7-m long free space absorp-tion cell by a d.c. glow discharge in BCl3. Rotational transitions of 11B35Cl and 11B37Cl in the ground vibrational state, which are split into a few components by the nuclear electric quadrupole interactions, have been observed and analyzed to yield molecular constants including the chlorine nuclear quadrupole coupling constant with high accuracy. The eQq constant thus determined is discussed along with those of other diatomic chlorides, to obtain information on the electronic structure of the molecules.
The Syntheses and Decompositions of Strontium and Barium Tetraphosphates
Authors: Watanabe Makoto , Maeda Mioko , Yamada Tamotsu
Published: July 2006

Strontium and barium tetraphosphates were made by hydrolyzing cyclo-tetraphosphate in a 5 mol dm−3 solution of sodium hydroxide, neutralizing the phosphate solution with 1 mol dm−3 hydrochloric acid, and then adding an aqueous solution of strontium or barium chloride to the solution. The P/M (M: Sr or Ba) ratio of the tetraphosphates was 1.3. The strontium and barium tetraphosphates were X-ray diffractometrically amorphous and contained about 23–14 and 14–8% of bound water depending on the washing conditions. They decomposed to phosphates having shorter chain lengths with the bond water in air at 25–30 °C or at a higher temperature. The decomposed phosphates were polymerized again above 150 °C and the products were mixtures of diphosphate and other polyphosphates.
Preparation and Spectroscopic Characterization of Substituted Pentacyanoferrates(II) with Phosphine or Phosphite Ligands
Authors: Inoue Hidenari , Sasagawa Masahiro , Fluck Ekkehard , Shirai Tsuneo
Published: July 2006

Twenty-two substituted pentacyanoferrates(II) with the formula Na3[Fe(CN)5PX3]·2H2O (PX3=phosphine or phosphite) have been prepared by ligand substitution of sodium amminepentacyanoferrate(II). The phosphite complexes show smaller isomer shifts than the phosphine complexes. The phosphine complexes involving an aryl or bulky phosphine exhibit larger quadrupole splitting than the phosphite complexes. These tendencies in M\ddotossbauer parameters are discussed in terms of the π-acceptor capability of the phosphine and phosphite ligands. The linear dependence of the isomer shifts on both CN stretching frequencies and d-d transition energies is interpreted on the basis of the predominance of iron-to-phosphorus π back-donation.
A Complete Series of [Co(acac)x(en)y(dmpe)z] Complexes
Authors: Ohishi Tomoji , Kashiwabara Kazuo , Fujita Junnosuke
Published: July 2006

A complete series of [Co(acac)x(en)y(dmpe)z] complexes was obtained by preparing four new complexes, [Co(acac)(dmpe)2]2+, [Co(en)2(dmpe)]3+, [Co(en)(dmpe)2]3+, and [Co(acac)(en)(dmpe)]2+, where acac, en, and dmpe denote an acetylacetonate ion, ethylenediamine, and 1,2-bis(dimethylphosphino)ethane, respectively. Except for [Co(acac)(dmpe)2]2+, the three new complexes were resolved into optical isomers by SP-Sephadex column chromatography. Absorption and circular dichroism spectra of all the complexes were recorded and compared with one another.
The Synthesis of (+)-Coleon A
Authors: Matsumoto Takashi , Imai Sachihiko , Hirata Takashi , Fukuda Yutaka , Yamaguchi Tadashi , Inoue Kazuhiro
Published: July 2006

Partial methylation of (R)-6-hydroxy-3-(3-hydroxypropyl)-7-isopropyl-3,4-dimethylnaphtho[2,3-b]furan-2(3H)-one followed by benzylation afforded the 6-benzyloxy-3-(3-methoxypropyl) derivative, which was converted into the 9-acetyl derivative by the series of reactions; sodium borohydride reduction, acetylation, alkaline hydrolysis, and Jones oxidation. This was oxidized with m-chloroperbenzoic acid to give the 9-acetoxy-5,8-quinone derivative, which was further converted into the 5,6,8,9-tetraacetoxy-3-(3-hydroxypropyl) derivative by hydrogenolysis, reductive acetylation, and demethylation. The tetraacetate in pyridine was treated with o-nitrophenyl selenocyanate in the presence of tributylphosphine and the resulting selenide was oxidized with hydrogen peroxide to give the 3-allyl derivative. This was converted into (+)-coleon A lactone by alkaline hydrolysis and subsequent oxidation. Finally, (+)-coleon A lactone was reduced with sodium borohydride to give (+)-coleon A which was also obtained by lithium aluminium hydride reduction of the 3-allyl derivative.
Cyclic Phosphorylation Reaction of Diols with Tri(1-imidazolyl)phosphine
Authors: Shimidzu Takeo , Yamana Kazushige , Kanda Naoya , Kitagawa Susumu
Published: July 2006

Tri(1-imidazolyl)phosphine (1) gave the cyclic phosphite quantitatively in the reactions with the diols possessing favorably placed hydroxyl groups in which the distance between the two oxygen atoms is 2.7–3.0 Å. The both five- and six-membered cyclic phosphites were obtained quantitatively from the reactions of the diols possessing flexible chains with 1. The course of the selective formation of ribonucleoside 2′,3′-cyclic 1-imidazolylphosphonite was interpretated by the higher reactivity of 1 toward the 2′- or 3′-hydroxyl group than toward the 5′-hydroxyl group of ribonucleoside.
The Vibrational Spectra and Thermodynamic Functions of 2,3-Dichloropyridine
Authors: Medhi Kanak Chandra
Published: July 2006

The infrared spectrum in the vapor, liquid, solution, and solid phases and the laser Raman spectrum in the liquid state have been measured for 2,3-dichloropyridine. A complete vibrational assignment is given. Ideal gas state thermodynamic functions of the molecule are computed over the temperature range 200–1500 K.
Infrared Spectra of Ammonia Adsorbed on Titanium Dioxide
Authors: Hino Masao , Mikami Yasuko
Published: July 2006

IR spectra of ammonia adsorbed on titanium dioxide were measured including those of partially deuterated ammonia. The results were compared with spectra reported in the literature.
The Wavelength Dependence of the Photochemical Reaction of 9-Anthracenecarbaldehyde with 2-Methyl-2-butene
Authors: Tanaka Fujio , Yamashita Shigeru
Published: July 2006

Photochemical reaction of 9-anthracenecarbaldehyde with 2-methyl-2-butene was studied under irradiation of >410 and 366 nm. Oxetane formation is predominant in both the wavelength cases, as revealed through isolation of reaction products and examination of their NMR, mass, and UV spectra.
Chirality of Waugh-type Enneamolybdomanganate(IV) Heteropolyanion. Observation of a Pfeiffer Effect
Authors: Nomiya Kenji , Kobayashi Ryoichi , Miwa Makoto
Published: July 2006

Enneamolybdomanganate(IV), [MnIV-Mo9O32]6−, so-called Waugh-type heteropolyanion, has a chirality based on the D3 symmetry around an MnO6 octahedron. Attempts to resolve the racemic polyanion have been unsuccessful. A Pfeiffer effect was observed for the tetrabutylammonium salt in organic media containing l-brucine sulfate as an environment substance. This is the third example of heteropolyanions which show an optical activity.
The Reactivity of Radical Anions Generated by Electron-transfer Reaction of Allyl Acetates
Authors: Tsujimoto Kazuo , Kamiyama Yojiro , Furukawa Yuji , Ohashi Mamoru
Published: July 2006

Photoinduced electron-transfer reactions of 3-(2-naphthyl)-2-butenyl acetate gave the reduced products, while the electrochemical and Birch reduction of the acetate furnished (E)-2-(2-naphthyl)-2-butene as the sole product. One-electron reduction was suggested by mechanistic studies of the photoreaction on the basis of deuterium incorporation into the products. A similar mechanism can operate in the photoreduction of cinnamyl acetate.
The Crystal and Molecular Structure of trans(O)·mer(N)-(S-(2-Aminoethyl)-l-homocysteinato)(glycinato)cobalt(III) Perchlorate
Authors: Okamoto Ken-ichi , Suzuki Masutaro , Einaga Hisahiko , Hidaka Jinsai
Published: July 2006

The crystal and molecular structure of the title complex, trans(O)·mer(N)-[Co(l-aehc)(gly)]+, has been determined by the X-ray analysis. This isomer has Δ configuration. The sulfur donor atom of the coordinated l-aehc has R configuration and the six-membered N–S chelate ring takes a chair conformation.
Reaction of Bis(2-methyl-8-quinolinolato)cobalt(II) with Nitrogen Monoxide
Authors: Miki Eiichi , Saito Katsunori , Mizumachi Kunihiko , Ishimori Tatsujiro
Published: July 2006

[Co(C10H8NO)2]·H2O (C10H8NO−=2-methyl-8-quinolinolate ion) reacted with nitrogen monoxide in dichloromethane to give unstable compounds, [Co(C10H8NO)2(NO)2] and [NO]3[Co(C10H8NO)2(NO3)(NO2)] with liberation of dinitrogen oxide. The compounds were characterized by 15N-isotopic effect observed on the IR spectra.
A Photochemically Induced Novel Ring Enlargement Reaction. Reaction of Cation Radical Derived from 7,8-Bis(methoxycarbonyl)-9-(4-methoxyphenyl)-1-phenyl-3,4-benzo-9-azabicyclo[4.2.1]non-3-ene-2,5-dione
Authors: Maruyama Kazuhiro , Ogawa Takuji
Published: July 2006

By oxidation with molecular oxygen, photoadducts 2 of 1-(4-methoxyphenyl)-1a-phenyl-1a,7a-dihydro-1H-naphth[2,3-b]azirine-2,7-dione with olefins afforded cation radicals of 2 in acidic media such as CF3CO2H or HClO4. On irradiation, the cation radicals gave ring enlarged isomers 10,11-bis(methoxycarbonyl)-1-phenyl-3,4-benzo-7,8-(3′-methoxybenzo)-9-azabicyclo[4.3.2] undec-3,7-diene-2,5-dione (3).
Molecular Structure of 3,4,6-Tri-O-acetyl-1,2-O-[(1S)-1-(2-p-bromophenyl)-9H-imidazo[1,2-a]benzimidazol-3-yl]ethylidene]-α-d-glucopyranose Acetone Solvate
Authors: Takayanagi Hiroaki , Ogura Haruo , Tsuzuno Nobuyasu , Kubota Isao , Iitaka Yoichi
Published: July 2006

The structure of a product from a reaction mixture of 2-(p-bromophenyl)-9H-imidazo[1,2-a]benzimidazole and 2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl bromide in the presence of NaI, hexamethyldisilazane, and (NH4)2SO4 has been established as 3,4,6-tri-O-acetyl-1,2-O-[(1S)-1-[2-p-bromophenyl)-9H-imidazo[1,2-a]benzimidazol-3-yl]ethylidene]-α-d-glucopyranose by means of X-ray crystal structure analysis.
Convenient Preparation of Methylthiomethyl p-Tolyl Sulfone Starting from Dimethyl Sulfoxide
Authors: Ogura Katsuyuki , Yahata Nobuhiro , Watanabe Jun-ichi , Takahashi Kazumasa , Iida Hirotada
Published: July 2006

An efficient method for preparing methylthiomethyl p-tolyl sulfone was accomplished by the Pummerer reaction of dimethyl sulfoxide with acetic anhydride followed by treatment of the resulting acetoxymethyl methyl sulfide with sodium p-toluenesulfinate in the presence of sodium acetate in acetic acid.
A 1H and 31P NMR Study of Phenylphosphonous Dichloride Partially Oriented in a Nematic Phase
Authors: Saito Koji , Yoshino Akihiro , Yoshida Tadayoshi , Takahashi Kensuke
Published: July 2006

The 1H and 31P NMR spectra of phenylphosphonous dichloride dissolved in a nematic phase of N-(p-ethoxybenzylidene)-p-butylaniline (EBBA) have been analyzed, and the structure of the proton and phosphorus skeleton has been determined.
An X-Ray Diffraction Study on the Structures of Mono(glycinato)nickel(II) and Tris(glycinato)nickelate(II) Complexes in Aqueous Solution
Authors: Ozutsumi Kazuhiko , Ohtaki Hitoshi
Published: July 2006

The structures of mono(glycinato)nickel(II) and tris(glycinato)nickelate(II) complexes in aqueous solution were determined by the X-ray diffraction method. From the analysis of the radial distribution curve of solution A, in which the hexaaqua- and mono(glycinato)nickel(II) ions coexisted (the mole ratio Cgly/CNi=0.792, where Ci denotes the total concentration of species i), we found that the mono(glycinato)nickel(II) complex combined with four water molecules at the distance of (2.08±0.01) Å, the bond being longer than the Ni–OH2 bond (2.04 Å) within the [Ni(OH2)6]2+ ion. The Ni–O and Ni–N bond lengths within the mono(glycinato)nickel(II) complex were essentially the same and (2.09±0.02) Å. Therefore, the mono(glycinato)nickel(II) ion has a practically regular octahedral structure. The nonbonding Ni···C distance was also determined to be (2.87±0.02) Å. The X-ray scattering data of solutions having the Cgly/CNi mole ratio of 3.24 (solution B) and 3.94 (solution C), in both of which almost all nickel(II) ions formed the [Ni(gly)3]− complex, showed that the tris(glycinato)nickelate(II) complex had a slightly distorted octahedral structure with the Ni–O and Ni–N bond lengths of (2.03±？.01) Å and (2.14±？.01) Å, respectively. The nonbonding Ni···C(COO), Ni···C(CH2) and Ni···O(O=C) distances were (2.82±？.02) Å, (2.96±？.02) Å, and (4.07±？.03) Å, respectively.
Oxidized Rubredoxin Models. II. Iron(III) Complexes of Z-Cys-Pro-Leu-Cys-OMe and Z-Cys-Thr-Val-Cys-OMe
Authors: Nakata Michio , Ueyama Norikazu , Terakawa Toshitsugu , Nakamura Akira
Published: July 2006

Fe(III) complexes of cysteine-containing peptides such as Z–Cys–Pro–Leu–Cys–OMe and Z–Cys–Thr–Val–Cys–OMe corresponding to the Fe binding amino acid sequences in Cl. pasteurianum rubredoxin were prepared in solution and characterized by the absorption, circular dichroism (CD), and magnetic circular dichroism (MCD) spectra and were compared with those of the Fe(III) complexes of Z–Cys–Ala–Ala–Cys–OMe, Z–Ala–Cys–OMe, and Z–Cys–Ala–Cys–OMe. These model compelxes exhibited the existence of an electronic configuration and a core structure similar to that of native rubredoxin. The thermal stabilities of the Fe(III) pep tide complexes decrease in the following order, Z–Cys–Thr–Val–Cys–OMe>Z–Cys–Ala–Ala–Cys–OMe>Z–Cys–Pro–Leu–Cys–OMe\simeqZ–Ala–Cys–OMe>>Z–Cys–Ala–Cys–OMe.
Asymmetric Synthesis of α-Deuterated α-Amino Acids through Nonenzymatic Transamination Reaction and the Determination of Their Enantiomeric Excesses
Authors: Tachibana Yoji , Ando Makoto , Kuzuhara Hiroyoshi
Published: July 2006

Optically active α-deuterated α-amino acids were prepared in methano-d through Zn2+-catalyzed transamination reaction between the chiral pyridoxamine analogs, (R)- or (S)-15-aminomethyl-14-hydroxy-5,5-dimethyl-2,8-dithia[9] (2,5)pyridinophane and various α-keto acids with enantiomeric excesses ranging from 40 to 94%. Aliphatic α-keto acids gave α-deuterated α-amino acids, whereas aromatic ones possessing a methylene group between the carbonyl group (ketone) and the aromatic ring underwent concomitant deuterium substitution at the active methylene group to give the amino acids deuterated at both α- and β-positions of the carboxyl group. The use of the (S)-pyridoxamine analog gave the (R)-deuterated α-amino acids in excess and vice versa. The enatiomeric excesses of the amino acids were determined through the analyses of 1H NMR spectra of the Schiff bases produced by the condensation of the amino acids with the chiral pyridoxal analog, (R)- or (S)-15-formyl-14-hydroxy-2,8-dithia[9](2, 5)pyridinophane. The azomethine protons of the diastereomeric Schiff bases were clearly resolved in the spectrum and their intensities well reflected the amount of the diastereomers.
Photochemical Reactions of 2-(Dimethylcarbamoyl)quinolines
Authors: Ono Isao , Hata Norisuke
Published: July 2006

2-(Dimethylcarbamoyl)quinolines are converted into 2-(methylaminoacetyl)quinolines (2) and 2-methyl-1H-pyrrolo[3,4-b]quinolin-3(2H)-ones (3) by irradiation in a nitrogen atmosphere. The reaction was quite efficient in acetonitrile but inefficient in hydrocarbon solvents and ethanol. The introduction of a chlorine atom to the 4-position of a quinoline nucleus caused an increase of the yield of 3 in company with a decrease of the yield of 2. On the other hand, irradiation in an oxygen atmosphere afforded 2-(methylcarbamoyl)quinolines as a main product but 2 and 3 were minor products. The results of quenching and sensitization experiments confirmed that the triplet π,π* state was responsible for the formation of those products. It is suggested that the reaction involves zwitterionic intermediates formed via Type II hydrogen abstraction by the ring nitrogen from the N-methyl group.