bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic Properties of 8H-Type Hexagonal Ba(Na1/4Ru3/4)O3
Authors: Kim In-Seon , Nakamura Tetsuro , Itoh Mitsuru
Published: June 2006

The magnetic properties of 8H-type hexagonal-type Ba(Na1/4Ru3/4)O3 having a 2D geometry of Ru5+(t2g3) ions were studied by magnetic-susceptibility measurements in the temperature range 5 K < T < 700 K. In this structure, the face-shared RuO6 octahedra form (Ru2O9)8− clusters with a 2D array, which are sandwiched by 2D layers of the NaO6 and the RuO6 corner-shared octahedra. The magnetic data show an antiferromagnetism-like behavior, and could be well fitted to a Curie-Weiss law above 520 K with μeff = 3.74 μB and θ = −1330 K. At a lower temperature range of 262 K < T < 520 K, it showed a reduced magnetic moment of μeff = 2.32 μB and θ = −221 K by a new Curie–Weiss law fit. The χ(T) behavior showed a strong external field dependence below 262 K, and magnetic anomaly peaks could be observed in low-field FC data at 30, 110, and 180 K, respectively. The magnetic properties of Ba(Na1/4Ru3/4)O3 are discussed concerning both a long-range 3D antiferromagnetic order and a spin-glass-like behavior.
Lithium Diffusion in LixCoO2 Electrode Materials
Authors: Nuspl Gerhard , Nagaoka Masataka , Yoshizawa Kazunari , Mohri Fumihito , Yamabe Tokio
Published: June 2006

The minimum energy migration path and the minimum barrier height of lithium diffusion are discussed for the layer compound LixCoO2. The Universal Force Field (UFF) is adapted for use in solid state compounds. Molecular dynamics simulations with additional impulse dynamics method, performed at a microcanonical ensemble, point out that the lithium migration between the Co–O octahedron layers takes place by ion hopping from one octahedral to another octahedral site via an interstitial tetrahedral site. The barrier height of lithium migration is estimated to be 28.7 kJ mol−1 (0.30 eV) for an original layer distance of 2.54 Å; a potential energy profile is developed from molecular mechanics calculations. The observation that the repulsive van der Waals interaction between Li+ and neighboring O2− ions is the most important contribution to the barrier height is consistent with the fact that the activation energy of lithium diffusion is very sensitive to the layer distance, within the experimentally observed values.
Charge Effects in Photoinduced Electron-Transfer Reactions between [Ru(bpy)3]2+ and Viologen Derivatives
Authors: Hamada Taisuke , Tsukamoto Masaya , Ohtsuka Hiroshi , Sakaki Shigeyoshi
Published: June 2006

Photoexcited *[Ru(bpy)3]2+ is oxidatively quenched by methylviologen (MV2+) and 1,1′-bis(2-carboxyethyl)-4,4′-bipyridinium (BCEBP2+) with a similar rate constant at pH 2.2; kqobs = 1.48 × 109 and 1.58 × 109 mol−1 dm3 s−1 (30 °C) for MV2+ and BCEBP2+, respectively. However, *[Ru(bpy)3]2+ is much more slowly quenched by MV2+ than by BCEBP0 at pH 5.0, where the superscript “0” represents that BCEBP is neutral; kqobs = 1.01 × 109 and 1.74 × 109 mol−1 dm3 s−1 for MV2+ and BCEBP0, respectively. The reverse electron-transfer reaction between [Ru(bpy)3]3+ and one-electron-reduced ·BCEBP+ (krevobs = 3.33 × 109 mol−1 dm3 s−1) proceeds slightly more rapidly than the reaction between [Ru(bpy)3]3+ and ·MV+ (krevobs = 2.80 × 109 mol−1 dm3 s−1) at pH 2.2 (30 °C), while the former reaction (krevobs = 5.85 × 109 mol−1 dm3 s−1) proceeds 2-times as rapidly as the latter reaction (krevobs = 2.74 × 109 mol−1 dm3 s−1) at pH 5.0. These differences at pH 5.0 between MV2+ and BCEBP0 are interpreted in terms of charge effects on the diffusion and diffusional dissociation of an exciplex and an encounter complex. The electron-transfer reactions in the exciplex and the encounter complex have been analyzed according to Marcus theory. The difference in an electronic coupling matrix element (Hrp) between MV2+ and BCEBP2+ or 0 is discussed in terms of the charge effects and steric effects.
Rotational Effects on the Channel Three Decay in Benzene: in Support of the Preisomerization Mechanism
Authors: Kanamaru Nobuaki
Published: June 2006

The “Channel 3” phenomena in benzene were investigated concerning a model scheme as an extension of that applied for a typical intermediate case molecule, pyrazine. Using a multiple doorway-states formalism, the difficulties in interpreting such as insufficient density of states for the intermediate dark levels were eliminated based on a preisomerization diagram involving a benzene isomer, most probably benzvalene. By a detailed examination of information about the title subject in the literature concerning both experiments and theory, several questions were raised and answered while making proposals for further study.
Inherent Automorphism and Q-Conjugacy Character Tables of Finite Groups. An Application to Combinatorial Enumeration of Isomers
Authors: Fujita Shinsaku
Published: June 2006

Q-Conjugacy character tables are proposed for finite groups and applied to combinatorial enumeration. Thus, the maturity of an irreducible representation is related to the maturity of a finite group by means of the relationship between the inherent automorphism of the group and its inner portion. As a result, a character table is transformed into a more concise form called a Q-conjugacy character table. Matured characters are defined as dominant-class functions on the basis of such a Q-conjugacy character table. Thereby, a matured character is represented by a linear combination of Q-conjugacy characters. By starting from Q-conjugacy character tables, characteristic monomial tables for finite groups are obtained. They are applied to combinatorial enumeration of isomers.
Structure and Electrochemical Properties of Directly Bound Dinuclear Cobaltadithiolene Complexes. Substituent Effect on Reduction Potentials and Mixed-Valence States
Authors: Akiyama Takeo , Amino Masaki , Saitou Tsutomu , Utsunomiya Koutoku , Seki Ken-ichi , Ikoma Yoshiharu , Kajitani Masatsugu , Sugiyama Toru , Shimizu Kunio , Sugimori Akira
Published: June 2006

The X-ray structures and electrochemical properties of the dinuclear cobaltadithiolene complexes, μ-(1,4-disubstituted 1,3-butadiene-1,2,3,4-tetrathiolato)-bis[(η5-cyclopentadienyl)cobalt(III)], have been investigated. In the diphenyl derivative, two benzene rings in the same molecule are located face to face with the distance of 3.5 Å, while in the dimethyl derivative, two methyl groups are in remote positions. However, in the electrically neutral dinuclear complexes, there is no evidence for the intramolecular interaction between two aryl groups in solutions. Electrochemical and spectrochemical investigations revealed that in electrically neutral state, the interaction between two cobaltadithiolene moieties is small, while in monoanioic state it becomes greater. The Hammett’s plot for ΔEr1/2 (ΔEr1/2 = Er1/2(red.1) − Er1/2(red.2)) shows that the electron-attracting substituents can stabilize the mixed-valence state, [Co(II)–Co(III)]−. The smaller ΔEr1/2 values for the complexes having aryl substituents are due to the smaller interactions between the anioic and neutral moieties, because of the steric hindrance of aryl groups which inhibit the conjugation of the two cobaltadithiolene rings.
Potential Sweep Voltammetry of Ion-Transfer at Liquid/Liquid Interface with Preceding Chemical Reaction. Determination of the Rate and Equilibrium Constants from Voltammetric Curves
Authors: Katano Hajime , Senda Mitsugi
Published: June 2006

The behavior of potential sweep voltammograms for the ion-transfer across the liquid/liquid interface with preceding chemical reactions is discussed. The theoretical results are expressed in the form of the working curves for the peak current, peak potential, and half-peak potential as a function of the kinetic-current parameter, which contains the rate and equilibrium constants of the preceding chemical reaction and the rate of the potential sweep. The working curves are applied to analyze the voltammograms for the transfer of Pb2+ ion to nitrobenzene facilitated by 1,4,7,10,13,16-hexathiacyclooctadecane present in nitrobenzene from aqueous medium containing citrate3− ion. The dissociation and association rate constants and the formation constant of Pb2+–citrate3− complex in W-phase are 4.5 × 104 s−1 and 8.0 × 1010 M−1 s−1and 106.3 M, respectively.
Spectro-Diffractometry for Chemical-State Analysis Based on In-Advance Simulations
Authors: Xiao Yanan , Hayakawa Shinjiro , Gohshi Yohichi , Oshima Masaharu , Okudera Hiroki , Toraya Hideo , Ohsumi Kazumasa
Published: June 2006

We performed an in-advance simulation and experiments involving resonant X-ray powder diffraction with the incident X-ray energy being near to the absorption edge of a particular element in order to distinguish two chemical states of that element based on the principle of spectro-diffractometry. According to the simulation, we found reflections that are relatively sensitive to the exchange of the two anomalous scattering factors (f′) of the specified element at two crystallographic sites. The simulation and experiment results demonstrated that it is possible to obtain f′ curves for the two chemical states by measuring only a few peaks that are sensitive to f′ without greatly increasing the refinement errors, and that the way of selecting the peaks greatly influence the results. In other words, in-advance simulations are very important in this method. This method may make it possible to obtain nearly the same result in one-tenth machine time, and, moreover, to obtain site-selective XANES for powder samples using limited machine time.
Syntheses and Properties of a New Type of Lewis Acids Incorporating Linked Bisphenoxide Moiety
Authors: Ohba Yoshihiro , Ito Kazuaki , Maeda Hiroyuki , Ebara Hiroaki , Takaki Shin , Nagasawa Tomomi
Published: June 2006

Several ligands for a new type of Lewis acid, which incorporates two linked phenols, were synthesized and the reaction of these ligands with trimethylaluminum quantitatively gave Lewis acids. These Lewis acids were found to be an efficient promoter for the rearrangement of epoxides to carbonyl compounds as well as a useful protector of acetophenone against hydride-reduction. The VT-NMR spectrum and NOESY spectrum of a 1 : 1 complex of Lewis acid 2a (methyl[2,2′-(m-xylene-α,α′-diyl)bis(4,6-di-t-butylphenoxido)aluminum and acetophenone provided data on the structure of a complex of acetophenone and 2a.
The Regioselective 1,4-Addition Reaction of Alkenylboronic Acids to α,β,α′,β′-Unsaturated Ketones
Authors: Hara Shoji , Shudoh Hisashi , Ishimura Shigeyuki , Suzuki Akira
Published: June 2006

The effect of substituents on the double bond of α,β-unsaturated ketones for the 1,4-addition reaction rate of alkenylboronic acids induced by cyanuric fluoride was studied in detail. When the steric hindrance around the β-carbon of the unsaturated ketones increased, the 1,4-addition reaction rate significantly decreased. An alkyl substituent on the α-carbon was also found to significantly affect the 1,4-addition reaction. From these results, unsymmetric α,β,α′,β′-unsaturated ketones (10a—f) were designed for the regioselective 1,4-addition reaction with alkenylboronic acids (4a—j). Since they have substituents to disturb the 1,4-addition reaction on only one double bond, the alkenylboronic acids reacted with them from only one side to selectively provide γ,δ,α′,β′-unsaturated ketones (11a—q). Further transformations of the resulting γ,δ,α′,β′-unsaturated ketones were also performed.
Photoacid and Photobase Generators: Prospects and Their Use in the Development of Polymeric Photosensitive Systems
Authors: Shirai Masamitsu , Tsunooka Masahiro
Published: June 2006

This article describes the recent progress in the preparation of a set of compounds which can generate acids or bases upon irradiation of light. These compounds are called photoacid generators and photobase generators, respectively. Photoacid generators can be divided into two groups according to their characteristics; i.e., ionic- and non-ionic compounds. Photobase generators are fewer than photoacid generators. These compounds are widely used in the field of polymeric photosensitive systems such as photoinitiated polymerization, photoinduced crosslinking of polymers and oligomers, photoinduced degradation of polymers, and photoinduced transformation of functional groups in polymer chains. In particular, this article focuses on the applications of photoacid and photobase generators to promote the development of photoresist and UV curing materials.
Solid State Photoisomerization of But-3-en-1-yl Group in Cobalt Complexes
Authors: Yamada Taro , Ohashi Yuji
Published: June 2006

The but-3-en-1-yl group bonded to the cobalt atom in some cobaloxime complexes is isomerized to the but-2-en-1-yl group in the solid state on exposure to a xenon lamp. In order to make clear the relationship between the reaction rate and the crystal structure, six complexes with different axial base ligands were prepared; piperidine, 1, 1-vinylimidazole, 2, pyrrolidine, 3, 1-methylimidazole, 4, 4-t-butylpyridine, 5, and triphenylphosphine, 6. The crystal structures were determined by X-ray analyses and the reaction rates were estimated from the change of the 1H NMR spectra observed in several intermediate stages. One of the photo products, which has 1-vinylimidazole as an axial base ligand, 7, was prepared separately and its crystal structure was also analyzed. A pair of the but-3-en-1-yl groups are in contact with each other around an inversion center in the crystal structures of 2, 5, and 6, whereas the but- 3-en-1-yl groups in 1, 3, and 4 are isolated from the other but-3-en-1-yl groups of the neighboring molecules in their crystal structures. The reaction rates of the former complexes are significantly greater than those of the latter complexes, except 2. This suggests that the cooperative motion of the but-3-en-1-yl groups plays an important role in the process of the isomerization. A pair of the but-3-en-1-yl groups around an inversion center in 2 are too closely packed for the isomerization to occur even if the cooperative motion is taken into account.
Ion Fragment Imaging of the Photodissociation of Methyl Iodide Small Clusters at 266 nm
Authors: Tanaka Yoshiki , Kawasaki Masahiro , Matsumi Yutaka
Published: June 2006

Photofragment iodine atoms and methyl radicals from the photodissociation of small clusters of methyl iodide at 266 nm were detected, using ion photofragment imaging spectroscopy. Three different components of the I+ image were observed with average laboratory translational energies of the I fragments,  = 2, 16, and 25 kcal mol−1 and anisotropy parameters, β = 0, 2.0 ± 0.6, and 2.1 ± 0.5, respectively. Similarly, for CH3+three different components in the CH3+ image correspond to average laboratory translational energies,  = 5, 25, and 38 kcal mol−1 and β = 0, 2.0 ± 0.2, and 2.2 ± 0.6, respectively. These results suggest the following reaction mechanisms; a) a CH3I chromophore in small clusters is excited to the A band (n,σ*) system of free CH3I, survives intact within the clusters and dissociates, b) dissociation of the CH3I moiety in the small clusters that have two adjacent iodine atoms results in the formation of slow photofragment iodine atoms and fast methyl radicals, and c) dissociation of other types of small clusters results in the formation of fast iodine atoms and slow methyl radicals.
EPR Spectra and Structure of the Radical Cations of Fluorinated Ethylenes and Propenes
Authors: Itagaki Yoshiteru , Shiotani Masaru , Hasegawa Akinori , Kawazoe Hisao
Published: June 2006

EPR spectra for the radical cations of a series of fluorinated ethylenes and propenes, generated by irradiation with γ-rays in halocarbon solid matrices, have been observed at low temperature. The spectra consist of a hyperfine structure with a nearly axial symmetry mainly due to fluorine nuclei. For the trifluoro olefin cations, CF2=CFX+ (X = H, CH3, or CF3), the experimental spectra were successfully analyzed in terms of the three 19F nuclei with coaxial parallel components. This may strongly suggest a planar structure for the radical cations, similarly to the case of the CF2=CF2+ cation already reported. On the other hand, for mono- and di-fluoro olefin radical cations, it is difficult to conclude the planar structure unequivocally from the experimental 19F and 1H hf splittings. Thus, the optimized geometry of the radical cations was calculated by an ab initio MO method. In contrast with the ethylene cation and the propene cation, having nonplanar twisted structures, the fluorinated ethylene and propene cations are concluded to have planar structures. Calculations at the INDO levels including the evaluation of interatomic dipole-dipole interactions were done for the geometries of the radical cations optimized by the ab initio method. The calculated results strongly support the EPR spectra observed and assigned to the radical cations.
Thermochromic Crystals of the CT Complex between N-Salicylidene-2-aminopyridine and 1,3,5-Trinitrobenzene
Authors: Tanaka Masashi , Imai Takayuki , Goto Takehiko , Taka Jun-ichiro , Akamatsu Mitsuhiro , Kashino Setsuo , Mogi Kouichi
Published: June 2006

N-Salicylidene-2-aminopyridine (NSAP) and 1,3,5-trinitrobenzene (TNB) form two kind of crystalline (1/2) complexes, forms I and II. The thermochromism was observed in a charge transfer complex form I, but not in form II. The thermochromism of these crystals was studied based on the temperature dependence of the X-ray analysis and the IR and visible absorption spectra together with the theoretical analysis.
Enhanced Emission of Nd3+ in Liquid Systems: Formation of Symmetrical Rigid Shells of Tightly Solvated DMSO Molecules and Weakly Coordinated Low-Vibrational β-Diketonato Ligands
Authors: Hasegawa Yasuchika , Iwamuro Mitsunori , Murakoshi Kei , Wada Yuji , Arakawa Ryuichi , Yamanaka Tatsuhiko , Nakashima Nobuaki , Yanagida Shozo
Published: June 2006

Coordination structures of neodymium(III) complexes with some β-diketones were investigated in terms of their correlations with emission efficiency in deuterated dimethylsulfoxide (DMSO-d6). The analysis of UV-vis spectra, 13C NMR, electrospray mass spectrometry (ES-MS) spectra, XANES and EXAFS analysis of tris(hexafluoroacetylacetonato)neodymium(III) complex, [Nd(hfa-H)3(H2O)2], and tris[bis(perfluorooctanoyl)methanato]neodymium(III), [Nd(pom-H)3], in DMSO indicated that the deuterated tris(hexafluoroacetylacetonato)neodymium(III), Nd(hfa-D)3, and deuterated tris[bis(perfluorooctanoyl)methanato]neodymium(III), Nd(pom-D)3, in DMSO-d6 should have a symmetrical, rigid and bulky shell composed of six inner-coordinating DMSO molecules and three weakly coordinating hfa-D and pom-D molecules. The improvement in the emission efficiency of the neodymium complexes with the low vibrational and weakly coordinating β-diketonates in DMSO-d6 was ascribed to their symmetrical rigid coordination structures, which should suppress radiationless transition via vibrational excitation and energy migration in the fluid system.
Bis(1-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane) Peroxodisulfate: A Mild and Efficient Oxidant for Cleavage of Nitrogen Double Bonds and Oxidation of Alcohols under Anhydrous Conditions
Authors: Hajipour Abdol Reza , -Baltork Iraj Mohammadpoor , Kianfar Godaraz
Published: June 2006

Bis(1-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane) peroxodisulfate (1), is readily prepared as an orange solid from commercially available 1,4-diazabicyclo[2.2.2]octane and potassium peroxodisulfate. This reagent easily converts hydrazones, semicarbazones, oximes, and alcohols to the corresponding carbonyl compounds with excellent yields.
Zinc Metal-Promoted Stereoselective Olefination of Aldehydes and Ketones with gem-Dichloro Compounds in the Presence of Chlorotrimethylsilane
Authors: Ishino Yoshio , Mihara Masatoshi , Nishihama Shintaro , Nishiguchi Ikuzou
Published: June 2006

A combination of zinc metal and a catalytic amount of chlorotrimethylsilane has been found to promote the transformation of various aldehydes and ketones with gem-dichloro compounds, such as benzylidene dichloride (1a) and methyl dichloroacetate (1b), to the corresponding cross-coupling products, such as substituted styrene 3 and methyl acrylates 4 derivatives, under mild reaction conditions in THF. The E-isomer of the corresponding alkenes was obtained stereoselectively in good-to-excellent yields. The reaction serves as a very convenient one-pot procedure.
Synthesis and Structure of Sulfur-Bridged [1·n](2,5)Thiophenophanes (n = 4—6)
Authors: Katano Naoki , Sugihara Yoshiaki , Ishii Akihiko , Nakayama Juzo
Published: June 2006

Sulfur-bridged [1·n](2,5)thiophenophanes (n = 4—6) were prepared by cyclization of dibromo derivatives of the corresponding linear oligo(thio-2,5-thienylenes) (1) on reactions with Na2S. The best results were obtained by heating 1 and Na2S in the presence of Cs2CO3 in NMP (24% yield for n = 4, 16% for n = 5, and 10% for n = 6). The reactions gave less satisfactory results either in the presence of CuI (Cu2O) or in the absence of these additives. The results of the X-ray structural analyses of these three compounds are also reported.
Synthesis of Carbosilane Compounds Functionalized with Three or Four β-Cyclodextrin Moieties. Use of a One-Pot Reaction in Liquid Ammonia for Birch Reduction and the Subsequent SN2 Replacement
Authors: Matsuoka Koji , Terabatake Mikiko , Saito Yosuke , Hagihara Chiharu , Esumi Yasuaki , Terunuma Daiyo , Kuzuhara Hiroyoshi
Published: June 2006

As a basic model reaction for assembling specific functional carbohydrate molecules on a novel core substance by making covalent bonds, an efficient one-pot reaction involving Birch reduction and a subsequent SN2 replacement was developed, employing trivalent and tetravalent carbosilane bromides as the core and monodeoxy-monomercapto-β-cyclodextrin as the functional carbohydrate. It was confirmed that carbosilane derivatives containing a suitable spacer molecule were of wide applicability as a new core substance for the construction of diverse functional materials.
Absolute Conformation and Chiroptical Properties. VI. 2,2′,3,3′-Tetramethoxy-9,9′-bitriptycyl: A Stereochemical Analog of 1,2-Disubstituted Ethane with Identical Substituents
Authors: Toyota Shinji , Yasutomi Akihiro , Kojima Hiroharu , Igarashi Yuko , Asakura Mitsuhiro , Oki Michinori
Published: June 2006

The title compound was prepared by addition of 4,5-dimethoxybenzyne to 9,9′-bianthryl. The rotational isomers, ap and ±sc, were separated by HPLC. The ±sc isomers were treated with sodium ethanethiolate to produce 3,3′-dihydroxy-2,2′-dimethoxy-9,9′-bitriptycyl, which was converted to the ester of (1S,5R,7R)-4-[(2-carboxy)benzoyl]-3-thia-4-azatricyclo[5.2.1.01,5]decane 3,3-dioxide. The resulting diastereomers were separated by HPLC. The isomers were hydrolyzed and methylated with dimethyl sulfate to yield optically active 2,2′,3,3′-tetramethoxy-9,9′-bitriptycyl. The absolute conformation of the tetramethoxy compound was determined by X-ray structure analysis of 3′-ester of (1S,5R,7R)-4-(2-carboxybenzoyl)-3-thia-4-azatricyclo[5.2.1.01,5]decane 3,3-dioxide derived from 3-hydroxy-2,2′,3′-trimethoxy-9,9′-bitriptycyl, followed by hydrolysis and then methylation. The CD spectrum of Msc-2,2′,3,3′-tetramethoxy-9,9′-bitriptycyl is reported.
A New Mesomorphism of the Alkyl 4-(2-Perfluoroalkyl)ethoxybenzoate Derivatives
Authors: Duan Meili , Okamoto Hiroaki , Petrov Vladimir F , Takenaka Shunsuke
Published: June 2006

The liquid-crystalline properties of the homologous members of alkyl 4-(2-perfluorooctyl)ethoxy-3-R-benzoates (R = H (1), NO2 (3), Br (4)) show a new mesomorphic behavior. The lower alkyl (methyl–pentyl) esters of 1 exhibit a smectic A phase, and the smectic A-isotropic transition temperature tends to decrease with increasing the carbon number of the alkyl group, where the layer spacing of the smectic A phase tends to become short with increasing carbon chain length. The hexyl–decyl esters are non-mesogenic, and the after members again show a smectic A phase. The similar trend has been found for 3 and 4. Homologous members of alkyl 4-(2-perfluorodecyl)ethoxybenzoates (2) also show a similar thermal behavior. The smectic properties are strongly dependent on the relative constitution of the perfluoroalkyl group to the alkyl one within the molecule. The molecular arrangement of the smectic A phase is discussed.
Bimolecular Reactions of Tetrakis(trialkylsilyl)disilenes with Various Reagents
Authors: Iwamoto Takeaki , Sakurai Hideki , Kira Mitsuo
Published: June 2006

Versatile reaction modes of tetrasilyldisilenes with various reagents have been disclosed. Typically, tetrakis(t-butyldimethylsilyl)disilene 1b reacts with 1-alkenes and a 1-alkyne having allylic hydrogens to afford the corresponding ene-addition products, while a reaction of 1b with styrene gives the [2+2] cycloaddition product. In contrast to tetra-t-butyldisilene and tetramesityldisilene, a reaction of 1b with a 1,3-butadiene gives quantitatively the [4+2] cycloaddition product. In accord with the biradical nature of disilene as predicted theoretically, tetrasilyldisilene 1b reacts with haloalkanes to provide the corresponding 2,3-dichlorotetrasilane or 2-alkyl-3-chlorotetrasilane probably via radical mechanisms. Facile nucleophilic additions of water, methanol, and methyllithium to 1b are indicative of the high electrophilicity of 1b.
Synthesis of IPN Polymer Hybrids by In-Situ Radical Polymerization Method and Their High Resistivity to Solvent Extraction
Authors: Tamaki Ryo , Horiguchi Takuya , Chujo Yoshiki
Published: June 2006

Two different types of polymer hybrids having an interpenetrating polymer network (IPN) of the organic gel and silica gel were prepared by the in-situ polymerization method. One type is the IPN polymer hybrids of poly(N,N′-dimethylacrylamide) gel and silica gel that were prepared by simultaneous polymerization of N,N′-dimethylacrylamide and N,N′-methylenebisacrylamide in a methanol solution of tetramethoxysilane (TMOS). The other type is IPN polymer hybrids of polystyrene gel and silica gel that were prepared by the polymerization of styrene monomer in the presence of divinylbenzene and TMOS. Radical polymerization of these organic monomers proceeded effectively in the sol-gel reaction mixture of TMOS, resulting in homogeneous glassy materials. The formation of IPN structure was confirmed by the solvent extraction. The loss of organic elements could be prevented in both cases by the incorporation of cross-linking points in the organic network. The homogeneity of these IPN polymer hybrids were supported by nitrogen porosimetry measurements. The results demonstrated that the porous silicas obtained from the polymer hybrids had high surface areas and large pore volumes and exhibited a sharp distribution of pore size below 2 nm in both types of IPN polymer hybrids. These results indicate a molecular-level integration of the organic gel and silica gel in the IPN polymer hybrids.
Semi-Emperical Calculation of the Transport Properties of Eight Binary Gas Mixtures at Low Density by the Inversion Method
Authors: Papari Mohammad Mehdi , Boushehri Ali
Published: June 2006

Viscosities, diffusion coefficients, and thermal-diffusion factors for eight equimolar binary gas mixtures (Ne+O2, Ne+CO2, Ne+N2O, Ne+SF6, Ar+O2, Ar+CO2, Ar+N2O, and Ar+SF6) were determined based on the principle of the corresponding states of viscosity using the inversion technique. The Lennard-Jones 12-6 potential energy function was used as the initial model potential required by the technique. Typically, the interaction potential of Ar+SF6 has been compared with those obtained from thermal-diffusion measurements. Our inverted potentials are in excellent agreement with it. The interaction potential energies from the inversion procedure reproduce the viscosities to within 1%, the diffusion coefficients to within 5%, and the thermal-diffusion factors to within 25%.
Molecular and Crystal Structures of Novel Second-Order Nonlinear Optical Crystals: α,α′-Dibenzylidenecycloalkanones
Authors: Kawamata Jun , Inoue Kuon , Inabe Tamotsu
Published: June 2006

X-Ray crystallographic analyses have been performed for the crystals of α,α′-dibenzylidenecycloalkanone (DBCA) derivatives which preferentially crystallize in non-centrosymmetric space groups and become second-order nonlinear optical crystals. We examined the obtained structures while paying attention to the intermolecular short contacts common to their structure. As a result, relatively short C–H···O contacts between the cycloalkanone rings were found for 8 out of 10 DBCA derivatives. The C–H···O distances for all cyclopentanone derivatives are almost the same as the sum of the van der Waals radius of carbon and that of oxygen; also, the geometrical characteristics found from the C–H···O contacts are consistent with the C–H···O hydrogen bond. The derivatives form a non-centrosymmetric one-dimensional chain with this contact. Their non-centrosymmetric crystal structures are led not only by their molecular shape, but also by this C–H···O interaction.
Hyperfine and Nuclear Quadrupole Couplings of the Coordinated Nitrogen of Oxovanadium(IV) Phthalocyanines Studied by Electron Spin-Echo Envelope Modulation Spectroscopy
Authors: Fukui Kouichi , Ohya-Nishiguchi Hiroaki , Kamada Hitoshi , Iwaizumi Masamoto , Xu Yuanzhi
Published: June 2006

Electron spin-echo envelope modulation (ESEEM) measurements were made for three substituted oxovanadium(IV) phthalocyanines ([VO(tcpc)], [VO(tbpc)], and [VO(tapc)]), where the phthalocyanine rings are modified with four carboxyl, t-butyl, and amino groups, respectively. The 14N hyperfine coupling (HFC) and nuclear quadrupole coupling (NQC) tensors of the phthalocyanine isoindole nitrogens were determined by computer simulations of orientationally selected ESEEM spectra. The HFC tensors of these three complexes were found to be almost identical, and no appreciable effects from the substituents were detected. The isotropic HFC constants, as determined by the simulations, are |Aiso| = 7.08, 7.08, and 7.05 MHz for [VO(tcpc)], [VO(tbpc)], and [VO(tapc)], respectively. The NQC constants were also found to be very similar to one another: e2qQ/h = 2.2, 2.1, and 2.0 MHz for [VO(tcpc)], [VO(tbpc)], and [VO(tapc)], respectively. However, the simulations revealed a difference in the orientation of the NQC unique axis, where the unique axis is parallel to the V–N bond in [VO(tcpc)] and [VO(tbpc)], whereas this axis is perpendicular to the V–N bond within the phthalocyanine plane in [VO(tapc)]. An analysis of the NQC parameters based on the Townes-Dailey model indicates an increase in the electron population of the nitrogen π orbital in [VO(tapc)], which is consistent with the expected effects of the amino group.
Langmuir Monolayers of Azobenzene Derivative with a Urea Head Group
Authors: Seki Takahiro , Fukuchi Takashi , Ichimura Kunihiro
Published: June 2006

An azobenzene (Az) containing amphiphile having a urea head group [N-(10-{4-[(4-hexylphenyl)azo]phenoxy})decylurea (6Az10-Urea)] was synthesized for the first time, and the spreading behavior, morphology, absorption spectral features, and photoreactivity of this amphiphile at the air–water interface was examined. The features of this monolayer were argued in comparison with those of a carboxylic acid derivative of the homologous structure. Polymer-like stable stable monolayers were formed form 6Az10-Urea both in the trans and cis forms of the Az unit, possibly indicating the formation of intermolecular bifurcated NH···O=C hydrogen bonds of urea heads. Unlike monolayers of simple long alkylureas, the present monolayer did not show a thermal phase transition within the temperature region examined (10—35 °C). In the trans-6Az10-Urea monolayer, the Az unit formed tilted aggregates. In this aggregation state, the trans-to-cis photoisomerization in the 6Az10-Urea monolayer was completely hindered despite the fact that the monolayer was more expanded than that of a corresponding carboxylic acid derivative in which the photoisomerization proceeded.
Solid–Solid Catalysis by Inorganic Solid Acids: Pinacol Rearrangement over a Heteropoly Compound Consisting of Fine Particles
Authors: Toyoshi Yasuo , Nakato Teruyuki , Okuhara Toshio
Published: June 2006

Solid-state pinacol rearrangement of 1,1,2-triphenyl-1,2-ethanediol was performed over various solid acids at room temperature. The reaction was initiated by grinding a mixture of the solid reactant and catalyst for 5 min at room temperature. Heteropoly compounds (Cs2.5H0.5PW12O40 and H3PW12O40) and polymer resins (Amberlyst®-15 and Nafion®/SiO2), all which possess strong acidities, were active, whereas H-ZSM-5, SiO2–Al2O3, and p-toluenesulfonic acid were inactive. Cs2.5H0.5PW12O40 showed the highest activity (per unit catalyst weight). The turnover number, which is defined as the number of molecules reacted divided by the number of protons on the surface, exceeded 20 for 9 h, indicating that the solid–solid reaction proceeded catalytically. This activity of Cs2.5H0.5PW12O40 was higher than that for the solid–liquid reaction carried out in chloroform at room temperature, demonstrating the superiority of the solid–solid catalysis. Powder X-ray diffraction measurements indicated that the reactant crystals became nearly amorphous by grinding with Cs2.5H0.5PW12O40, while the crystallinity of Cs2.5H0.5PW12O40 was unchanged. The microstructure built up from fine particles of Cs2.5H0.5PW12O40 would be favorable to intimate contact of the reactant with the catalyst.
Separation Behavior of Biological Constituents Having cis-Diol Groups through Interactions with Phenylboronic Acid Sites Introduced on the Inner Wall of a Fused-Silica Capillary
Authors: Tsukagoshi Kazuhiko , Hashimoto Masahiko , Otsuka Miwa , Nakajima Riichiro , Kondo Kazuo
Published: June 2006

Phenylboronic acid sites were introduced onto the inner wall of a fused-silica capillary through the polymerization of 3-acrylamidophenylboronic acid after activating the wall by a silane coupling reagent. The phenylboronic acid-modified capillary was examined from various viewpoints of separation chemistry. Nucleosides having cis-diol groups were mainly used as model samples. The phenylboronic acid-modified capillary successfully separated a mixture of nucleosides, for example, an adenosine and deoxyadenosine mixture, in capillary electrophoresis. The separation was based on an interaction between the cis-diol groups and the phenylboronic acid sites on the capillary wall. The cooperation of borate migration buffer with the modified capillary could improve the resolution. The separation of a d- and l-glucoses mixture was also indicated with the coexistence of β-cyclodextrin in electrophoresis using a modified capillary. Furthermore, mixtures of nucleosides were separated with satisfactory results by chromatography utilizing a solute-wall interaction in the modified capillary, where the eluate was delivered through the capillary by a gravity method without any electrophoresis. The separation of biological constituents in this study, which took advantage of the interaction between the solutes and the inner wall of the capillary, is interesting as a new separation technique in not only capillary electrophoresis, but also capillary chromatography.
Highly Efficient Solvent Extraction of Water-Soluble Macrocyclic Metal Ligands, Hydroxycalix[n]arene-p-sulfonates (n = 4, 6, 8) with Trioctylmethylammonium Chloride
Authors: Nishida Masashi , Sonoda Miwako , Ishii Daido , Yoshida Isao
Published: June 2006

Water-soluble hydroxycalix[n]arene-p-sulfonates, 1nn− (n = 4, 6, and 8), were quantitatively extracted from an aqueous solution into chloroform with trioctylmethylammonium ion (TMA+) over a wide pH range. The extraction reaction of 1nn− with TMA+Cl− and the extraction constants were determined from slope analyses of linearized extraction data and by the mole-ratio method. It was demonstrated that 1nn−, having n moles of sulfonato groups in an aqueous solution, could be extracted as 1n (TMA+)n by associating with n moles of TMA+ at a pH lower than that at which protonic dissociation of hydroxyl groups takes place, and that 1n (TMA+)(n+j) was extracted at a pH higher than that for j moles of hydroxyl groups dissociate to form 1n(n+j)−. The extractability of 1nn− increased in the order of n (4 < 6 < 8); also, the pH range where complete extraction took place became wider in the same order. As a possible application of the present extraction system, metal extraction with 144− was also shown for the purpose of selective separation of some metal ions.
Thermal Isomerization of mer-[RhH(SAr)(SiHAr′2)(PMe3)3] to fac-[RhH2{SiAr′2(SAr)}(PMe3)3] Involving Thiolato Group Transfer from Rh to Si
Authors: Osakada Kohtaro , Hataya Kouji , Yamamoto Takakazu
Published: June 2006

Heating of a benzene or toluene solution of mer-[RhH(SAr)(SiHAr′2)(PMe3)3] (Ar = C6H5, C6H4Me-p, C6H4OMe-p; Ar′ = C6H5, C6H4Me-p, C6H4F-p, C6H4CF3-p) at 30—50 °C gives fac-[RhH2{SiAr′2(SAr)}(PMe3)3] quantitatively through thiolato group transfer from Rh to Si. X-Ray structural analysis of fac-[RhH2{SiPh2(SPh)}(PMe3)3] reveals octahedral coordination with three PMe3 ligands at facial coordination sites, while the 1H NMR spectra show the presence of two equivalent hydrido ligands. The other Rh complexes are isolated or characterized in situ by means of NMR spectroscopy. The reaction of mer-[RhH(SC6H4Me-p)(SiHPh2)(PMe3)3] to form the Rh complex obeys first-order kinetics with the kinetic parameters: ΔG‡ = 98.6 kJ mol−1, ΔH‡ = 94.9 kJ mol−1, and ΔS‡ = −12 J mol−1 deg−1 at 298 K. The rate constants of the reaction of mer-[RhH(SC6H4X-p)(SiHPh2)(PMe3)3] (X = H, Me, OMe) increase with increasing Hammett constant σp of substituent X. The substituent of the diarylsilyl ligand of mer-[RhH(SC6H4X-p){SiH(C6H4Y-p)2}(PMe3)3] (X = Me or OMe; Y = H, Me, F, CF3) also influences the reaction rate constant, while the degree of enhancement is not directly related to the electron donating or withdrawing ability of substituent Y. Possible reaction mechanisms are discussed based on these results.
Oxidative Addition of a Hypervalent Transannular Sulfur–Sulfur Bond to a Pd(0) Complex: Synthesis and Crystal Structures of 1,5-Dithiacyclooctanepalladium(II) Bis(trifluoromethanesulfonate) Having Phosphine Ligands
Authors: Oshiki Toshiyuki , Mashima Kazushi , Yamagata Tsuneaki , Tani Kazuhide
Published: June 2006

A hypervalent compound 1,5-bis(trifluoromethylsulfonyloxy)-1λ4,5λ4-dithiabicyclo[3.3.0]octane (1) oxidatively reacted with Pd2(dba)3 (dba = dibenzylidene acetone) in acetonitrile to give a dicationic complex [Pd(dtco)(CH3CN)2](OTf)2 (2) (DTCO = 1,5-dithiacyclooctane), in which the DTCO ligand coordinated in cis-chelation to the palladium metal. Acetonitrile in 2 was labile enough to be readily replaced by phosphine ligands to give dicationic DTCO-phosphine palladium complexes of the formula [Pd(dtco)(L)2](OTf)2 (3: L = PMe2Ph; 4: L = PPh3; 5: L2 = 1,2-bis(diphenylphosphino)ethane; 6: L2 = (R)-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl). Molecular structures of 5 and 6 have been characterized by X-ray analysis, indicating that each of these two complexes consists of a discrete dicationic palladium(II) species [Pd(dtco)L2]2+ and two trifluoromethanesulfonate ions without any cation–anion bonding interaction, and revealing that the DTCO is coordinated to the palladium center as a bidentate ligand and that two phosphorus atoms ultimately coordinated to the metal in cis-fashion.
Preparation of Silanediyl-Bridged Fe–Fe and Fe–W Dinuclear Complexes. X-Ray Structures of [Cp*Fe(CO)(μ-CO){μ-Si(H)CHPh2}(CO)nMCp] (Cp* = C5Me5, Cp = C5H5, M = Fe, n = 1; M = W, n = 2)
Authors: Luh Lung-Shiang , Wen Yuh-Sheng , Tobita Hiromi , Ogino Hiroshi
Published: June 2006

Photolysis of a 2 : 1 mixture of [Cp*Fe(CO)2Me] and Ph2CHSiH3 produces mainly the mononuclear silyl complex [Cp*Fe(CO)2{Si(H)2CHPh2}] (1) together with two silanediyl-bridged diiron complexes: cis- and trans-[Cp*2(CO)2Fe2(μ-CO){μ-Si(H)CHPh2}] (2), and [{Cp*Fe(CO)2}2]. The trans-2 complex isomerizes to cis-2 photochemically, but no cis–trans isomerization occurs thermally below 100 °C. Photolysis of [CpFe(CO)2SiMe3] or [CpW(CO)3Me] in the presence of 1 produces novel silanediyl-bridged complexes [Cp*Fe(CO)(μ-CO){μ-Si(H)CHPh2}(CO)nMCp] (3: M = Fe, n = 1; 4: M = W, n = 2) in moderate yields. Complexes 3 and 4 have been characterized by X-ray diffraction analysis. To the best of our knowledge, complex 4 is the first example of a silanediyl-bridged Fe–W complex. The Cp and Cp* rings are mutually cis with the dihedral angle of 78.7(2)° in complex 3, but they are trans with the dihedral angle of 13.1(6)° in complex 4.
Steric Control of Polynuclear Manganese Complexes by the Use of Tripodal Tetradentate Ligands
Authors: Hirotsu Masakazu , Kojima Masaaki , Mori Wasuke , Yoshikawa Yuzo
Published: June 2006

Tripodal tetradentate ligands (H2L1: N,N-bis(2-hydroxybenzyl)-N′,N′-dimethylethylenediamine, H2L2: N-(3,5-di-t-butyl-2-hydroxybenzyl)-N-(2-hydroxybenzyl)-N′,N′-dimethylethylenediamine, H2L3: N,N-bis(3,5-di-t-butyl-2-hydroxybenzyl)-N′,N′-dimethylethylenediamine, H2L4: N,N-bis(2-hydroxy-3-methoxybenzyl)-N′,N′-dimethylethylenediamine, H2L5: N-(3,5-di-t-butyl-2-hydroxybenzyl)-N-(2-hydroxy-3-methoxybenzyl)-N′,N′-dimethylethylenediamine) made it possible to prepare sterically controlled polynuclear manganese complexes. In the presence of carboxylate ligands, in contrast to the L3 ligand which gave mononuclear MnIII complexes, the other ligands afforded mixed-valence trinuclear complexes with an MnIII–MnII–MnIII arrangement. In methanol, the general formula of the products is [Mn3(L)2(carboxylato)2(OCH3)2]. While preparations in acetonitrile generated [Mn3(L1)2(ba)4] (ba = benzoate(1−)) and [Mn3(L2)2(ba)2(OH)2]. The structure of [Mn3(L1)2(ba)4] was determined by X-ray analysis. The three manganese cores are arranged linearly, and the central and terminal ions are bridged by a phenolate and two carboxylate groups. In the case of the L5 ligand, dinuclear and tetranuclear complexes were also obtained and structurally characterized. In the dinuclear complex, [Mn(L5)(CH3OH)(OCH3)MnCl2], a distorted octahedral MnIII and a five-coordinated MnII site are bridged by a phenolate and an alkoxo oxygen donor. The tetranuclear complex, [Mn4(L5)2(ba)6], including an MnIII–MnII–MnII–MnIII arrangement, is regarded as a carboxylato bridged dimer of a dinuclear unit, [Mn(L5)(ba)2Mn]+. Because the bulkiness of the L5 ligand lies between the L2 and L3 ligands, the dinuclear unit is favorable. Variable-temperature magnetic susceptibility measurements showed the ferromagnetic spin-exchange coupling for [Mn(L5)(CH3OH)(OCH3)MnCl2] and the antiferromagnetic one for [Mn3(L1)2(ba)4]. The phenolato and alkoxo bridges give rise to the ferromagnetic exchange interactions between MnIIIand MnII ions. On the other hand, the antiferromagnetic interactions stem from carboxylato bridges.
Generation and Carbonyl Addition Reactions of Dibromofluoromethyllithium Derived from Tribromofluoromethane as Applied to the Stereoselective Synthesis of Fluoro Olefins and 2-Bromo-2-fluoro-1,3-alkanediols
Authors: Shimizu Masaki , Yamada Nobuko , Takebe Yoko , Hata Takeshi , Kuroboshi Manabu , Hiyama Tamejiro
Published: June 2006

The treatment of tribromofluoromethane with BuLi in THF–Et2O (2 : 1) at −130 °C generated dibromofluoromethyllithium, which was allowed to react smoothly with a coexisting aldehyde or ketone (RR′C=O) to give fluorinated alcohol RR′C(OH)CFBr2 (3) in good yield. Alcohol 3 was converted stereoselectively to (E)-1-bromo-1,2-difluoro olefin 5 via fluorination with Et2NSF3, followed by dehydrobromination with lithium 2,2,6,6-tetramethylpiperidide, while (E)-1-bromo-1-fluoro olefin was obtained with high selectivity by acetylation of 3, followed by reductive elimination using EtMgBr/(i-Pr)2NH. Difluoro olefin 5 underwent a cross-coupling reaction with an aryl, alkenyl, or alkynylmetal reagent to afford the corresponding fluoro olefin with retention of configuration. On the other hand, the treatment of RCH[OCH2O(CH2)2OCH3]CFBr2 with BuLi at −130 °C in the presence of 4-heptanone gave the corresponding adduct diastereoselectively. The stereochemical outcome is explained in terms of chelation between lithium and oxygen atoms of the (2-methoxyethoxy)methyl group. Starting with 2-phenylpropanal, a product is obtained highly selectively containing three contiguous stereocenters including a –CFBr– moiety.
Regioselective Reduction of the Homoisoflavone System with Dialkylboranes in the Presence of Palladium Catalysts
Authors: Hoshino Yukio , Tanaka Hiroto , Takeno Noboru
Published: June 2006

(E)-3-Benzylidene-4-chromanones were regioselectively reduced to 3-benzyl-4-chromanones through the 1,4-addition of dialkylboranes, especially 9-borabicyclo[3.3.1]nonane, in excellent yields. The reaction was efficiently promoted by some palladium catalysts. Among them, dichloro[1,1′-bis(diphenylphosphino)ferrocene]palladium(II) was most effective, followed by palladium(II) chloride. Furthermore, the reaction was characteristic of the structurally rigid exo-cyclic α,β-unsaturated ketones, such as (E)-3-benzylidene-4-chromanone, while no reaction occurred in the case of 3-benzyl-4H-chromen-4-one, which is an endo-cyclic one. 2-Benzylidene-3,4-dihydro-1(2H)-naphthalenone and 2-benzylideneindanone were similarly reduced at an olefin moiety only as the result of a 1,4-reduction.
Palladium(0)-Catalyzed Domino Cyclization-Carbonylation of Alkenyl-Allenyl-Allylic Acetate
Authors: Doi Takayuki , Takasaki Masaru , Nakanishi Sadahiro , Yanagisawa Arata , Yamamoto Keiji , Takahashi Takashi
Published: June 2006

The Pd(0)-catalyzed domino cyclization-carbonylation of 5,8-dimethyl-5-(1,2-propadienyl)-2,8-nonadienyl acetate (7) was achieved at a rather higher temperature. The tricyclic and tetracyclic products, 15 and 16, were produced in 77% combined yield via five and six consecutive carbon–carbon bond formations, each step proceeding in > 94% yield.
Regioselective Synthesis of Quinolin-8-ols and 1,2,3,4-Tetrahydroquinolin-8-ols by the Cyclization of 2-(3-Hydroxyphenyl)ethyl Ketone O-2,4-Dinitrophenyloximes
Authors: Uchiyama Katsuya , Ono Ayako , Hayashi Yujiro , Narasaka Koichi
Published: June 2006

Cyclization of 2-(3-hydroxyphenyl)ethyl ketone O-2,4-dinitrophenyloximes proceeds on the oxime nitrogen atom by the treatment with NaH and then with 2,3-dichloro-5,6-dicyano-p-benzoquinone and acetic acid to yield quinolin-8-ols regioselectively. The reaction in the presence of Na[BH3(CN)] affords 1,2,3,4-tetrahydroquinolin-8-ols. The present cyclization proceeds via alkylideneaminyl radical intermediates generated by the single electron transfer between 3-hydroxyphenyl and 2,4-dinitrophenyl moieties.
Preparation of a Lithium Ion Conductor through Polyethylene Glycol and LiSO3CF3 Sorption in Zeolite
Authors: Tang Weiping , Ogo Yoshiaki , Minamimoto Noriko , Takeoka Mitsunobu
Published: June 2006

A lithium ion conductor was prepared by adsorbing polyethylene glycol (PEG) in mesopores of zeolite and it was found that the interface between PEG and zeolite plays a significant role in lithium ion transport.
K5[W4O8(H2BO4)(HPO4)2(PO4)2]·0.5H2O: A Tungsten Borophosphate with a Novel Sandwich-like Layered Structure
Authors: Mao Shao-Yu , Kang You-Jun , Liu Wei , Mi Jin-Xiao , Zhao Jing-Tai
Published: June 2006

The first tungsten borophosphate compound, K5[W4O8(H2BO4)(HPO4)2(PO4)2]·0.5H2O, has been synthesized under mild hydrothermal conditions, and the crystal structure with a new stoichiometry (B:P ratio 1:4) exhibits a novel sandwich-like layered structure.
Synthesis of β-Amino Ketones by Iridium(III)-catalyzed Direct-Mannich Reaction
Authors: Sueki Shunsuke , Igarashi Takeyuki , Nakajima Takayuki , Shimizu Isao
Published: June 2006

The direct-Mannich reaction of ketones 1, aldehydes 2, and anilines 3 was studied using catalytic amount of transition-metal complexes. The trivalent iridium complex, [IrCl2(H)(cod)]2, catalyzed the direct-Mannich reaction effectively to give various β-amino kenotes in good yields under mild conditions.