bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Preparation of (C6H11)3Sb(OH)Y and Their Infrared Spectra
Authors: Kawasaki Yoshikane , Yamamoto Yasushi , Wada Masanori 
Published: July 2006

Abstract
Tris(cyclohexyl)hydroxoantimony(V) compounds, (C6H11)3Sb(OH)Y, Y=Cl, Br, CH3COO, and NO3, were prepared by the hydrolysis of μ-oxo-bis[tris(cyclohexyl)haloantimony(V)], [(C6H11)3SbX]2O, in a mixed solvent of acetone and water(7:3) or by a reaction of silver salts with [(C6H11)3SbX]2O in the same solvent. When Y=Cl and Br, the dehydration of the hydroxo compounds, giving the μ-oxo compounds, [(C6H11)3SbY]2O, occurred readily. However, when Y= CH3COO and NO3, the hydroxo form is stable. In the IR spectra of these hydroxo compounds in dichloromethane solution, the ν(O–H) band was observed at ca. 3630 cm−1 and the ν(Sb–O) band, at 565–513 cm−1. The hydrolysis of several μ-oxo compounds, [R3SbY]2O, R=CH3, C2H5, i-C3H7, C6H5, and p-CH3C6H4, Y=Cl, Br, CH3COO, and NO3, in a water-saturated dichloromethane solution was studied by using the IR spectra. All the compounds were hydolyzed in this solvent, but only the starting μ-oxo compounds were recovered from this solution.
Syntheses of Acyclic Polyethers Containing a Ferrocene Nucleus and Its Extraction Ability
Authors: Akabori Sadatoshi , Ohtomi Michiko , Sato Masaru , Ebine Seiji 
Published: July 2006

Abstract
Acyclic polyethers (7) (containing a ferrocene nucleus in both terminal sites) were synthesized by a one-pot reaction of 1,1′-diacetoxyferrocene with halide. Also, ferrocene derivatives (11) having polyethylene glycols were synthesized by the reaction of potassium salt of hydroxyferrocene with dihalide in DMF. On the addition of alkali metal thiocyanate in methanol, a hypsochromic shift and an increasing intensity of the absorption band at 438 nm were observed in ferrocene-containing polyethers 7, suggesting the complexing of 7 with cations. However, a similar spectral change could not be observed in 11. 7a extracts silver and thallium ions most effectively, the extraction efficiency of several metal cations being in this order: Ag+&gt;Tl+&gt;Cs+&gt;K+&gt;Li+&gt;Na+.
Hydroxymethylation and Alkoxymethylation of Methacryloguanamine
Authors: Seo Toshihiro , Abe Kenji , Kakurai Toshio 
Published: July 2006

Abstract
The reaction of 2-amino-4-(substituted amino)-6-isopropenyl-1,3,5-triazines (methacryloguanamine) with formaldehyde gave several new monomers having hydroxymethyl groups in satisfactory yields. These monomers were easily converted into the corresponding alkyl ethers with methanol. Their melting points and solubilities were affected considerably by the species and the number of substituted groups. Especially, tetrakis(hydroxymethyl)methacryloguanamine and its methoxymethyl derivative were readily soluble in water and nonpolar solvents, respectively. The former was polymerized and crosslinked smoothly to yield a insoluble polymer. Copolymerization of the latter with methyl methacrylate, however, gave soluble polymers, formed flexible and tough films. Similarly, the reactive polymers were prepared from polymers containing guanamine structure by hydroxymethylation followed by etherification.
Persistent Nitrogen-centered Free Radicals, N-(Arylthio)-3,5-di-t-butylphenylaminyls. The Reactions with Phenols
Authors: Miura Yozo , Yamamoto Akifumi , Kinoshita Masayoshi 
Published: July 2006

Abstract
The reactions of N-(4-chlorophenylthio)-3,5-di-t-butylphenylaminyl (1) with phenols were examined. The reaction with 2,6-dimethyl- and di-t-butylphenols gave 2,6-dimethyl- and di-t-butyl-p-benzoquinone 3,5-di-t-butylphenylimines, respectively, in excellent yields. In the reaction with unsubstituted phenol, 2,6-bis[N-(4-chlorophenylthio)-3,5-di-t-butylphenylamino]-p-benzoquinone 3,5-di-t-butylphenylimine was obtained in 32–56% yields. On the other hand, the reactions with p-substituted phenols such as p-cresol, p-t-butylphenol, and 2,4-di-t-butylphenol, gave phenols which were substituted by 1 at the ortho-positions to the OH group. Furthermore, the reactions with o-cresol, 2,6-di-t-butyl-p-cresol, and 1-naphthol were examined. On the basis of these results, plausible mechanisms for the reactions are presented.
A New Synthesis of Triphenodithiazines and Triphenodithiazinequinoes
Authors: Nishi Hisao , Hatada Yuichi , Kitahara Kiyoshi 
Published: July 2006

Abstract
A new class of 6,13-bis(arylamino)triphenodithiazines has been synthesized by condensing chloranil with arylamines followed by the reaction of the resulting 2,5-bis(arylamino)-3,6-dichloro-1,4-benzoquinones with zinc 2-aminobenzenthiolates (4) in the presence of a base in Methyl Cellosolve. On the other hand, the reaction of 2,5-dianilino-3,6-dichloro-1,4-benzoquinone (3a) with 4 in DMF proceeded unexpectedly to give 7,14-dihydro-6,13-triphenodithiazinequinones by eliminating the anilino groups of 3a.
Conformations and Restricted Rotation about Amide C–N Bonds of 2,2-Dichloro-1′-formyl-3′,4′-dihydrospiro[cyclopropane-1,2′(1′H)-quinoline] and Related Compounds
Authors: Suezawa (née Endo) Hiroko , Hirota Minoru , Sugiura Michiharu , Hamada Yoshiki 
Published: July 2006

Abstract
Conformational preference and rotational barriers of 1′,1′,2,2-tetrachloro-3′-formyl-1′a,7′b-dihydrospiro[cyclopropane-1,2′(3′H)-cyclopropa[c]quinolines] (1) and related N-formyl heterocyclic compounds were determined by 1H- and 13C-NMR spectroscopy. The sp-conformer is usually more preferable in 1 and their rotational barriers about amide C–N bond are within a relatively narrow range from 70.7 to 72.8 kJ mol−1. Infrared carbonyl absorptions of these compounds also support the preferred conformation from the NMR data. The results were discussed from the view point of N–C=O conjugation.
Binuclear Metal Complexes. IL. Synthesis, ESR, and Electrochemical Properties of Strati-bis Copper(II)–Nickel(II) Complexes
Authors: Okawa Hisashi , Kakimoto Miyuki , Izumitani Tatuo , Nakamura Masaaki , Kida Sigeo 
Published: July 2006

Abstract
Strati-bis copper(II)–nickel(II) complexes, CuNi(R-sata) and CuNi(R-sacta) (R=H, 5-Me, 5-Br), have been prepared, where H4(R-sata) and H4(R-sacta) denote 1,2,3,4-tetrakis(R-salicylideneamino)-2,3-dimethylbutane and 1,2-bis(R-salicylideneamino)-1,2-bis(R-salicylideneaminomethyl)cyclohexane, respectively. ESR spectra of the complexes (frozen chloroform solution at liquid nitrogen temperature) showed a tetragonal pattern with a hyperfine coupling constant A⁄⁄ smaller than that of the relevant mononuclear copper(II) complex. Based on cyclic voltammetry and differential pulse polarography, it was shown that the Cu(II)→Cu(I) reduction occurs at a higher potential than that of the mononuclear reference complex. The ESR and electrochemical properties have been interpreted in terms of the stacking of the CuN2O2 and NiN2O2 planes and hence the electron delocalization over the whole molecule through the ligand π-system.
Cathodic Reduction of Ubiquinone-10 Dissolved in Carbon-paste Electrode
Authors: Erabi Tatsuo , Tanaka Masaya 
Published: July 2006

Abstract
Carbon-paste electrodes were prepared with use of ubiquinone-10 dissolved in organic liquids, 1-chloronaphthalene, 1-bromonaphthalene, 1-methylnaphthalene and undecane. Ubiquinone-10 shows a well-defined, pH-dependent cathodic reduction wave in each liquid system and its reduction seems to proceed with two electrons and a proton transfer around neutral pH. The experimental results indicate the wave to be diffusion-controlled, and the apparent diffusion coefficient was additionally calculated in each liquid system.
Alkylation of the Sulfur- and Nitrogen-containing Compounds Analogous to Thiazoline Systems
Authors: Ohara Yoshio , Akiba Kin-ya , Inamoto Naoki 
Published: July 2006

Abstract
N,N-Dimethyl-2-(alkylthio)ethylamines and 3-methylthiazolidines underwent N-methylation both with trimethyloxonium tetrafluoroborate (3a) and with methyl iodide. In the methylation of N,N-dimethyl-o-(methylthio)aniline, the main reaction was S-methylation. On the other hand, in the o-ethylthio derivative, S-methylated product was major with methyl iodide, while N-methylated product was major with 3a. In the N-ethyl or N-benzyl derivative, only S-methylation occurred with both reagents. 3-Methyl-2, 2-diphenyl-2,3-dihydro-benzothiazole gave S-methylated product with 3a, suggesting that S-methylation becomes major when the 2-substituent is bulkier. 4-Methyl-3,4-dmydro-2H-benzo[b][1,4]thiazine was methylated on the nitrogen with 3a, while it gave S-methylated product with methyl iodide. Phenothiazines and 1-dialkylamino-8-(methylthio)naphthalenes gave only S-methylated products. The selective S-methylation in the case of N-methylation was carried out through protonation on the nitrogen atom followed by methylation with 3a. Possibility of intramolecular interaction between sulfonio and amino groups has been discussed based on their NMR data.
Dimeric Copper(II) Acetate Complexes of Thiazoles and Oxazoles
Authors: Tokii Tadashi , Muto Yoneichiro 
Published: July 2006

Abstract
Copper(II) acetate monoadducts, Cu(CH3COO)2·L (L=thiazole, benzothiazole, benzoxazole, 2-methylbenzothiazole, 2-methylbenzoxazole, 2,4-dimethylthiazole, or 2,4,5-trimethylthiazole) were prepared, and they all show antiferromangnetism (−2J=318–344 cm−1) of copper(II) dimer type. The variation in magnetic interaction with the steric nature of the ligand, L, is discussed.
Preparation and Molecular Structure of cis-β,trans(sec-N,P)-{(2-Aminoethyl)dimethylphosphine}(3,7-diazanonane-1,9-diamine)cobalt(III) Bromide Dihydrate
Authors: Ohishi Tomoji , Kashiwabara Kazuo , Ito Haruko , Ito Tasuku , Fujita Junnosuke 
Published: July 2006

Abstract
The reaction of trans-[CoCl2(2,3,2-tet)]+(2,3,2-tet: 3,7-diazanonane-1,9-diamine) with (2-aminoethyl)dimethylphosphine (edmp) afforded only one geometrical isomer of [Co(edmp)(2,3,2-tet)]3+, the structure of which was determined by X-ray analysis to have the cis-β,trans-(sec-N,P) configuration.
Kinetic Study of Aqueous Decompositions of N-(2-Haloethyl)-N′-cyclohexyl-N-nitrosoureas. Effect of Haloethyl Group on the Preference in Decomposition Pathways
Authors: Yoshida Kitaro , Yano Kazuyuki 
Published: July 2006

Abstract
The aqueous decompositions of the title nitrosoureas under various pH conditions were studied kinetically to generalize their hydrolytic mechanisms. The relative decomposition rates of these analogs were in order of the leaving ability of the halogen moiety, which also affected on the preference in their reaction pathways.
Pyridinium-1-thioacylaminides
Authors: Yoshida Hiroshi , Urushibata Kiyomi , Ogata Tsuyoshi 
Published: July 2006

Abstract
Pyridinium-, 2-methylpyridinium-, and 2,6-dimethylpyridinium-1-thioacylaminides (5–7) were prepared from the corresponding unsubstituted pyridinium-1-aminides and methyl dithiocarboxylates in fairly good yields. The alkylation reaction of 5–7 took place exclusively on the thiocarbonyl sulfur, yielding pyridinium salts in quantitative yields. The NMR spectroscopic studies indicated that E and Z forms existed for these pyridinium salts. The thermal decomposition of 5–7 yielded the corresponding pyridine, nitrile, and sulfur in good yields.
Pseudo-sugars. IX. Synthesis of Three (Hydroxymethyl)cyclohexanepentols
Authors: Ogawa Seiichiro , Nakamura Toshinobu , Chida Noritaka , Suami Tetsuo 
Published: July 2006

Abstract
Three new Dl-(hydroxymethyl)cyclohexanepentols, of which configurations are related to biologically important chiro- and myo-inositols, have been synthesized as hexaacetates from Dl-tri-O-acetyl-(1,3/2,4)-4-benzoyloxymethyl-5-cyclohexene-1,2,3-triol by osmium tetraoxide-oxidation or peroxy acid-oxidation followed by acid hydrolysis, and their structures have been established by 1H NMR spectroscopy.
Studies on 2-Aziridinecarboxylic Acid. X. Simple Stereospecific Synthesis of Optically Active Cystine and threo-3,3′-Dimethylcystine
Authors: Nakajima Kiichiro , Okawa Kenji 
Published: July 2006

Abstract
The reaction of (2S)-Z–Azy–OBzl, (2S,3S)-Z–3-MeAzy–OBzl, and their enantiomers with H2S gave the optically active cysteine and thero-3-methylcysteine derivatives via the stereospecific ring-opening reaction of aziridine, and subsequent oxidation and deblocking procedure gave the titled compounds in good yields.
Lewis Acid Mediated Reaction of Trimethylstyrylsilanes with Thioacetal Derivatives
Authors: Hirao Toshikazu , Kohno Shuichiro , Ohshiro Yoshiki , Agawa Toshio 
Published: July 2006

Abstract
Treatment of trimethylstyrylsilanes with 1-ethoxy-1-(phenylthio)ethane or 2-ethoxy-1,3-dithiolane in the presence of Lewis acid gives the corresponding (E)-allyl sulfide or (E)-2-styryl-1,3-dithiolane, respectively. In both cases, a carbon-oxygen bond of thioacetal derivatives is cleaved selectively.
Preparation and Stereochemistry of Δ-sym-[(2S,2′S)-1,1′-Ethylenedipyrrolidine-2,2′-dicarboxylato]cobalt(III) Complexes with Various Bidentate Ligands
Authors: Okabayashi Minahiro , Okamoto Ken-ichi , Einaga Hisahiko , Hidaka Jinsai 
Published: July 2006

Abstract
Cobalt(III) complexes containing (2S,2′S)-1,1′-ethylenedipyrrolidine-2,2′-dicarboxylate (S,S-epro) and a bidentate ligand were prepared and characterized. The bidentate ligands were ethylenediamine, trimethylenediamine, oxalate, glycinate, (R)- or (S)-alaninate, (R)- or (S)-valinate, (R)- or (S)-prolinate, (R)- or (S)-pipecolate, sarcosinate, or N-ethylglycinate. The S,S-epro ligand coordinates stereoselectively to cobalt(III) ion to take only the Δ-sym configuration. The stereochemistry was discussed on the basis of the electronic absorption, CD, and 1H and 13C NMR spectra. The rate constants of isomerization and the Gibbs’ free energy difference (ca. 0.9 kJ mol−1) between the R(N) and S(N) isomers of the sarcosinato or N-ethylglycinato complex were investigated in relation to the interligand interaction. The thermodynamics and mechanisms of their isomerization process were little influenced by the N-alkyl groups.
The Temperature Dependence of the Ultrasonic Relaxation Process Due to Interaction between Water and Allyl Cellosolve
Authors: Nishikawa Sadakatsu , Yamaguchi Tatsuro 
Published: July 2006

Abstract
Ultrasonic absorption and velocity measurements have been performed in aqueous solutions of Allyl Cellosolve (ethylene glycol monoallyl ether) as functions of the concentration and the temperature. Only a single relaxational absorption has been observed in the frequency range from 15 to 220 MHz and, it has been attributed to the perturbation of the equilibrium expressed as AB\ightleftharpoonsA+B, where A and B are the solute and the solvent molecule respectively. The rate constants at various temperatures have been determined from the concentration dependence of the relaxation frequency, and the thermodynamic parameters associated with the reaction have been calculated. The enthalpy change has also been estimated from the concentration dependence of the maximum excess absorption per wavelength. From these results, it has been concluded that Allyl Cellosolve molecules act as water structure promoters and that the interaction between the solute and the solvent is due to hydrogen bonding. Furthermore, the rate and the thermodynamic properties obtained are compared with those for aqueous solutions of other ethers.
Cyclopropanation of Dimethyl Fumarate and Maleate with gem-Dihalides Catalyzed by Co(0)- or Ni(0)-Complex and Zinc
Authors: Kanai Hiroyoshi , Nishiguchi Yoshimasa , Matsuda Hideki 
Published: July 2006

Abstract
The reaction of bis(acetonitrile)bis(diethyl fumarate)cobalt(0) with dibromomethane gave diethyl trans-1,2-cyclopropanedicarboxylate in a 67% yield based on the cobalt complex. Dimethyl cis-1,2-cyclopropanedicarboxylate was obtained in a 52% yield from the reaction of dimethyl maleate with dibromomethane in the presence of acetonitrilebis(dimethyl maleate)nickel(0) accompanied by the formation of the trans-isomer in a 14% yield. The addition of zinc gave cyclopropanes in over 100% yields based on cobalt or nickel. 3-Methyl- and 3,3-dimethyl-1,2-cyclopropanedicarboxylic acid esters were produced by the reaction of dimethyl fumarate or maleate with 1,1-dibromoethane and 2,2-dibromopropane. The yield in the cobalt catalyst system decreases with an increase of substituents of gem-dibromides, while that in the nickel catalyst system does not vary appreciably. A small amount of dimethyl isopropenylsuccinate was formed as a by-product in the reaction of 2,2-dibromopropane. A mechanism is briefly discussed which involves metallacyclobutane as an intermediate.
Penetration of Lysine Hydrochloride into Lecithin Monolayers from Underlying Aqueous Solutions
Authors: Nakagaki Masayuki , Okamura Emiko 
Published: July 2006

Abstract
The surface pressure of the monolayers of dimyristoyl phosphatidylcholine (DMPC) on lysine mono- and dihydrochloride solutions was measured and the amount of positively charged lysine which had penetrated into a DMPC monolayer was calculated by successive approximation. The amount of penetration was smaller for lysine monohydrochloride than for the dihydrochloride. Moreover, both were smaller than that of uncharged lysine because mono- and dihydrochloride are more hydrophilic than uncharged lysine. The average area per molecule in the monolayer consisting of lysine and DMPC, A23, was obtained. In the case of charged lysine, A23 increased with the mole fraction of lysine in a monolayer, X2, in contrast it decreased with X2 in the case of uncharged lysine. The partial molecular area of positively charged lysine was considerably larger than that of uncharged lysine. This indicates that the remarkable expansion of a monolayer is caused by the penetration of positively charged lysine because of electrostatic repulsion in the monolayer. The effect of sodium chloride on the adsorption of lysine was also investigated, but the amount adsorbed was independent of the presence of 0.5 mol dm−3 sodium chloride.
NMR Studies of Picolyl-type Carbanions. VI. Anions Produced by Reactions of Methyl-substituted Quinolines and Isoquinolines with Butyllithium
Authors: Konishi Kazuyori , Takahashi Kensuke 
Published: July 2006

Abstract
The 13C and 1H NMR spectra have been observed for the title anions with lithium as a counter ion in polar solvents. Two kinds of anions are formed by lithium-proton exchange and addition of butyllithium. The charge distributions in the anions are discussed in terms of the σ-included ω-HMO method. The former anions can be regarded as picolyl-type carbanions, but the latter ones are ionic species having two of three basic characteristics on picolyl-type carbanions.
Mössbauer Spectroscopic Study of FeCl3-doped Polyacetylene
Authors: Sakai Hiroshi , Maeda Yutaka , Kobayashi Taka-aki , Shirakawa Hideki 
Published: July 2006

Abstract
Mössbauer spectra of FeCl3-doped polyacetylenes [CH(FeCl3)y]x (y=0.074, 0.087, and 0.13), which exhibit high electrical conductivities of ≈800, ≈800, and ≈100 S/cm at room temperature, have been measured at the temperatures of 290, 196, 78, and 5 K, respectively. The spectra consist of a superposition of two quadrupole-split doublets, described as doublet (A) and doublet (B), at 290, 196, and 78 K. At 5 K the doublet (A) splits into six lines arising from the magnetic hyperfine interaction, whereas the doublet (B) still remains paramagnetic. The doublet (B) increases remarkably in the Mössbauer absorption with decreasing temperature and is predominant. The values of the isomer shift, the quadrupole splitting, and the internal magnetic field, indicate that the iron compounds corresponding to the doublet (A) and (B) are FeCl2·nH2O (n=1 and/or 2) and FeCl4−, respectively. These results established that the mechanism of the FeCl3-doping process in polyacetylene is as follows:
2FeCl3+e−→FeCl4−+FeCl2,
FeCl2+nH2O→FeCl2·nH2O(n=1 and/or 2).
The Crystal Structure of Bis(2,2′-bipyridine)-catena-μ-tetrafluoroborato-copper(II) Tetrafluoroborate
Authors: Nakai Hisayoshi 
Published: July 2006

Abstract
The crystal structure of the title compound was determined by means of the X-ray diffraction technique. The crystal is triclinic, space group P\barl, a=11.288(8), b=15.186(17), c=7.368(4) Å, α=74.93(3), β=78.23(3), γ=65.92(3)°, and Z=2. The structure was solved by the heavy-atom method and refined by the least-squares method to R=0.068 for 3678 non-zero reflections. The crystal is composed of BF4− ions and polymeric chains of [Cu(BF4)(bpy)2+] in which a tetrafluoroborate ion bridges two adjacent copper atoms through its two fluorine atoms. The coordination polyhedron around the copper atom is a tetragonally distorted octahedron; the four nitrogen atoms of bipyridine molecules in the equatorial plane are arranged in a flattened tetrahedral manner (average Cu–N=1.99 Å) and the two axial Cu–F distances are 2.566(6) and 2.662(4) Å. In both bipyridine molecules, the two pyridine rings are twisted slightly from each other; the interplanar angle is 3.1° in one bipyridine ligand and 10.2° in the other.
Noncovalent Interactions in Metal Complexes. VI. Bonding Interaction between Chelate π-System and Menthyl Group in Copper(II), Nickel(II), and Palladium(II) Complexes of 1-l-Menthyloxy-3-benzoylacetone
Authors: Nakamura Michio , Okawa Hisashi , Kida Sigeo 
Published: July 2006

Abstract
Metal complexes, M(l-moba)2(H2O)n (M=Cu(II), n=0; Ni(II), n=2; Pd(II), n=0) and M(bpy)(l-moba)ClO4 (M=Cu(II), Pd(II)), where H(l-moba) denotes 1-l-menthyloxy-3-benzoylacetone, have been synthesized and characterized by means of elemental analyses, NMR spectra, electronic spectra, and circular dichroism spectra. In the NMR spectra of H(l-moba), Pd(l-moba)2, and Pd(bpy)(l-moba)ClO4, the methylene protons adjacent to the l-menthyloxy group were observed as AB quartet. The chloroform solutions of Cu(l-moba)2 and Cu(bpy)(l-moba)ClO4 showed a positive CD band at 15500 and 16200 cm−1, respectively. The chloroform solution of Ni(l-moba)2(H2O)2 also showed a weak, positive CD band near 16000 cm−1. When pyridine or t-butylamine was added to the chloroform solution of Cu(l-moba)2, a negative CD appeared around 17000 cm−1 attributable to the five-coordinate species Cu(l-moba)2B. On the other hand, with adding an amine to the chloroform solution of Ni(l-moba)2(H2O)2, the 16000 cm−1 CD band decreased its intensity and finally disappeared. Similar trend was observed when alcohol, DMSO, or DMF was added to the chloroform solution of Ni(l-moba)2(H2O)2. NMR and CD spectral results have been rationalized by assuming that the l-menthyl group interacts with the chelate ring of l-moba− and this interaction gives rise to a chirality around the metal ion.
Studies on the β-Turn of Peptides. III. Syntheses and Conformational Properties of N-(2,4-Dinitrophenyl)tetrapeptide p-Nitroanilides Related to β-Turn Preferring Sequences in Proteins
Authors: Sato Kazuki , Nagai Ukon , Higashijima Tsutomu 
Published: July 2006

Abstract
To confirm the general applicability of CD spectra of N-(2,4-dinitrophenyl(Dnp))tetrapeptide p-nitroanilides (pNA’s) to the analysis of β-turn preference of the tetrapeptide sequences, Dnp-pNA derivatives of some tetrapeptides related to β-turn preferring sequences in proteins were synthesized and subjected to CD and 1H NMR measurements. CD spectra of Dnp–Gly–l-Pro–l-Asn–Gly–pNA (5a) were just the mirror image of those of gramicidin S-model peptide, Dnp–Gly–d-Ala–l-Pro–Gly–pNA (6). This suggested that 5a strongly preferred the β-turn and the type of turn was different from that of 6. The relative intensities of Cotton effects of the tetrapeptide with the general structure Dnp–Gly–l-Pro–Y–Gly–pNA (Y=l-Asn, Gly, l-Ala, or l-Gln) roughly agreed with the bend potentials of the amino acid residues at the third position of β-turns in proteins reported by Chou and Fasman. The effects of changing the amino acid residues at the second position of β-turn were also examined.