- Synthesis, photophysical and electrochemical properties of aza-boron-diquinomethene complexes
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A series of aza-boron-diquinomethene (aza-BODIQU) complexes with different aryl-substituents (B1-B6) were synthesized and characterized. Their photophysical properties were investigated systematically via spectroscopic and theoretical methods. All complexes exhibit strong 1π-π* absorption bands and intense fluorescent emission bands in the visible spectral region at room temperature. The fluorescence spectra in solution show the mirror image features of the S0→S1 absorption bands, which can be assigned to the 1π-π*/1ICT (intramolecular charge transfer) emitting states. Except for B6, all complexes exhibit high photoluminescence quantum yields (ΦPL = 0.47-0.93). The spectroscopic studies and theoretical calculations indicate that the photophysical properties of these aza-BODIQUs can be tuned by the appended aryl-substituents, which would be useful for rational design of boron-fluorine complexes with high emission quantum yield for organic light-emitting applications.
- Wang, Danfeng,Liu, Rui,Chen, Chen,Wang, Shifan,Chang, Jin,Wu, Chunhui,Zhu, Hongjun,Waclawik, Eric R.
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Read Online
- Highly chemoselective deoxygenation of N-heterocyclic: N -oxides under transition metal-free conditions
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Because their site-selective C-H functionalizations are now considered one of the most useful tools for synthesizing various N-heterocyclic compounds, the highly chemoselective deoxygenation of densely functionalized N-heterocyclic N-oxides has received much attention from the synthetic chemistry community. Here, we provide a protocol for the highly chemoselective deoxygenation of various functionalized N-oxides under visible light-mediated photoredox conditions with Na2-eosin Y as an organophotocatalyst. Mechanistic studies imply that the excited state of the organophotocatalyst is reductively quenched by Hantzsch esters. This operationally simple technique tolerates a wide range of functional groups and allows high-yield, multigram-scale deoxygenation. This journal is
- Kim, Se Hyun,An, Ju Hyeon,Lee, Jun Hee
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supporting information
p. 3735 - 3742
(2021/05/04)
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- Highly Chemoselective Deoxygenation of N-Heterocyclic N-Oxides Using Hantzsch Esters as Mild Reducing Agents
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Herein, we disclose a highly chemoselective room-temperature deoxygenation method applicable to various functionalized N-heterocyclic N-oxides via visible light-mediated metallaphotoredox catalysis using Hantzsch esters as the sole stoichiometric reductant. Despite the feasibility of catalyst-free conditions, most of these deoxygenations can be completed within a few minutes using only a tiny amount of a catalyst. This technology also allows for multigram-scale reactions even with an extremely low catalyst loading of 0.01 mol %. The scope of this scalable and operationally convenient protocol encompasses a wide range of functional groups, such as amides, carbamates, esters, ketones, nitrile groups, nitro groups, and halogens, which provide access to the corresponding deoxygenated N-heterocycles in good to excellent yields (an average of an 86.8% yield for a total of 45 examples).
- An, Ju Hyeon,Kim, Kyu Dong,Lee, Jun Hee
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supporting information
p. 2876 - 2894
(2021/02/01)
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- Metal–Organic Layers Hierarchically Integrate Three Synergistic Active Sites for Tandem Catalysis
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We report the design of a bifunctional metal–organic layer (MOL), Hf12-Ru-Co, composed of [Ru(DBB)(bpy)2]2+ [DBB-Ru, DBB=4,4′-di(4-benzoato)-2,2′-bipyridine; bpy=2,2′-bipyridine] connecting ligand as a photosensitizer and Co(dmgH)2(PPA)Cl (PPA-Co, dmgH=dimethylglyoxime; PPA=4-pyridinepropionic acid) on the Hf12 secondary building unit (SBU) as a hydrogen-transfer catalyst. Hf12-Ru-Co efficiently catalyzed acceptorless dehydrogenation of indolines and tetrahydroquinolines to afford indoles and quinolones. We extended this strategy to prepare Hf12-Ru-Co-OTf MOL with a [Ru(DBB)(bpy)2]2+ photosensitizer and Hf12 SBU capped with triflate as strong Lewis acids and PPA-Co as a hydrogen transfer catalyst. With three synergistic active sites, Hf12-Ru-Co-OTf competently catalyzed dehydrogenative tandem transformations of indolines with alkenes or aldehydes to afford 3-alkylindoles and bisindolylmethanes with turnover numbers of up to 500 and 460, respectively, illustrating the potential use of MOLs in constructing novel multifunctional heterogeneous catalysts.
- Quan, Yangjian,Lan, Guangxu,Shi, Wenjie,Xu, Ziwan,Fan, Yingjie,You, Eric,Jiang, Xiaomin,Wang, Cheng,Lin, Wenbin
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supporting information
p. 3115 - 3120
(2020/12/09)
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- Visible light mediated selective oxidation of alcohols and oxidative dehydrogenation of N-heterocycles using scalable and reusable La-doped NiWO4nanoparticles
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Visible light-mediated selective and efficient oxidation of various primary/secondary benzyl alcohols to aldehydes/ketones and oxidative dehydrogenation (ODH) of partially saturated heterocycles using a scalable and reusable heterogeneous photoredox catalyst in aqueous medium are described. A systematic study led to a selective synthesis of aldehydes under an argon atmosphere while the ODH of partially saturated heterocycles under an oxygen atmosphere resulted in very good to excellent yields. The methodology is atom economical and exhibits excellent tolerance towards various functional groups, and broad substrate scope. Furthermore, a one-pot procedure was developed for the sequential oxidation of benzyl alcohols and heteroaryl carbinols followed by the Pictet-Spengler cyclization and then aromatization to obtain the β-carbolines in high isolated yields. This methodology was found to be suitable for scale up and reusability. To the best of our knowledge, this is the first report on the oxidation of structurally diverse aryl carbinols and ODH of partially saturated N-heterocycles using a recyclable and heterogeneous photoredox catalyst under environmentally friendly conditions.
- Abinaya, R.,Balasubramaniam, K. K.,Baskar, B.,Divya, P.,Mani Rahulan, K.,Rahman, Abdul,Sridhar, R.,Srinath, S.
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p. 5990 - 6007
(2021/08/24)
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- Monomeric vanadium oxide: A very efficient species for promoting aerobic oxidative dehydrogenation of N-heterocycles
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Monomeric active species are very interesting in heterogeneous catalysis. In this work, we proposed a method to prepare VOx-NbOy@C catalysts, which involve the one-pot hydrothermal synthesis of inorganic/organic hybrid materials containing V/Nb followed by thermal treatment under a reducing atmosphere. The prepared catalysts were characterized using different techniques, such as high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption fine structure spectroscopy. It was shown that monomeric VOx species were dispersed homogeneously in the catalysts. The VOx-NbOy@C catalysts displayed high performance in the aerobic oxidative dehydrogenation of N-heterocycles to aromatic heterocycles. It was demonstrated that the selectivity of reaction over the catalyst with a very small amount of V (0.07 wt%) was much higher than that over the NbOy@C, and the catalyst also exhibited excellent stability in the reaction. The detailed study indicated that monomeric VO2 species were the most effective for promoting the reaction. This journal is
- Xie, Zhenbing,Chen, Bingfeng,Zheng, Lirong,Peng, Fangfang,Liu, Huizhen,Han, Buxing
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p. 431 - 437
(2021/01/11)
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- Highly Ordered Mesoporous Cobalt Oxide as Heterogeneous Catalyst for Aerobic Oxidative Aromatization of N-Heterocycles
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N-heterocycles are key structures for many pharmaceutical intermediates. The synthesis of such units normally is conducted under homogeneous catalytic conditions. Among all methods, aerobic oxidative aromatization is one of the most effective. However, in homogeneous conditions, catalysts are difficult to be recycled. Herein, we report a heterogeneous catalytic strategy with a mesoporous cobalt oxide as catalyst. The developed protocol shows a broad applicability for the synthesis of N-heterocycles (32 examples, up to 99 % yield), and the catalyst presents high turnover numbers (7.41) in the absence of any additives. Such a heterogenous approach can be easily scaled up. Furthermore, the catalyst can be recycled by simply filtration and be reused for at least six times without obvious deactivation. Comparative studies reveal that the high surface area of mesoporous cobalt oxide plays an important role on the catalytic reactivity. The outstanding recycling capacity makes the catalyst industrially practical and sustainable for the synthesis of diverse N-heterocycles.
- Cao, Yue,Wu, Yong,Zhang, Yuanteng,Zhou, Jing,Xiao, Wei,Gu, Dong
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p. 3679 - 3686
(2021/06/18)
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- Covalent Organic Frameworks toward Diverse Photocatalytic Aerobic Oxidations
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Photoactive two-dimensional covalent organic frameworks (2D-COFs) have become promising heterogenous photocatalysts in visible-light-driven organic transformations. Herein, a visible-light-driven selective aerobic oxidation of various small organic molecules by using 2D-COFs as the photocatalyst was developed. In this protocol, due to the remarkable photocatalytic capability of hydrazone-based 2D-COF-1 on molecular oxygen activation, a wide range of amides, quinolones, heterocyclic compounds, and sulfoxides were obtained with high efficiency and excellent functional group tolerance under very mild reaction conditions. Furthermore, benefiting from the inherent advantage of heterogenous photocatalysis, prominent sustainability and easy photocatalyst recyclability, a drug molecule (modafinil) and an oxidized mustard gas simulant (2-chloroethyl ethyl sulfoxide) were selectively and easily obtained in scale-up reactions. Mechanistic investigations were conducted using radical quenching experiments and in situ ESR spectroscopy, all corroborating the proposed role of 2D-COF-1 in photocatalytic cycle.
- Liu, Shuyang,Tian, Miao,Bu, Xiubin,Tian, Hua,Yang, Xiaobo
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supporting information
p. 7738 - 7744
(2021/05/07)
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- Superacid-promoted synthesis of quinoline derivatives
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A series of vinylogous imines have been prepared from anilines and cinnamaldehydes. These substrates react in superacidic media to provide quinolines and related compounds. A mechanism for the conversion is proposed which involves the cyclization of dicationic superelectrophilic intermediates. Aromatization of the quinoline ring is thought to occur by superacid-promoted elimination of benzene.
- Klumpp, Douglas A.,Stentzel, Michael R.,Vuong, Hein
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- Reusable, homogeneous water soluble photoredox catalyzed oxidative dehydrogenation of N-heterocycles in a biphasic system: Application to the synthesis of biologically active natural products
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Herein, a simple and efficient method for the oxidative dehydrogenation (ODH) of tetrahydro-β-carbolines, indolines and tetrahydro-(iso)quinolines is described using a reusable, homogeneous cobalt-phthalocyanine photoredox catalyst in a biphasic medium. A biphasic system offers an advantage of easy separation of the product and an efficient reusability of the homogeneous photoredox catalyst. Also, the current system significantly helps to overcome the solubility issue of the substrate and catalyst at room temperature. Its potential applications to organic transformations are demonstrated by the synthesis of various biologically active N-heterocycles such as indoles, (iso)quinolines and β-carbolines and natural products such as eudistomin U, norharmane, and harmane and precursors to perlolyrine and flazin. Without isolation and purification, the catalyst solution can be reused up to 5 times with almost comparable reactivity. Furthermore, the efficiency of the reaction was demonstrated on a gram scale. To the best of our knowledge, this is the first report on ODH reactions using a non noble, reusable and homogeneous cobalt photoredox catalyst under environmentally friendly conditions.
- Abinaya, R.,Baskar, B.,Mariappan, M.,Prasanth, Arun,Sridhar, R.,Srinath, S.
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p. 2575 - 2587
(2020/05/13)
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- Catalytic Aerobic Dehydrogenatin of N-Heterocycles by N-Hydoxyphthalimide
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Catalytic methods for the aerobic dehydrogenation of N-heterocycles are reported. In most cases, indoles are accessed efficiently from indolines using catalytic N-hydroxyphthalimide (NHPI) as the sole additive under air. Further studies revealed an improved catalytic system of NHPI and copper for the preparation of other heteroaromatics, for example quinolines. (Figure presented.).
- Chen, Weidong,Tang, Hao,Wang, Weilin,Fu, Qiang,Luo, Junfei
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supporting information
p. 3905 - 3911
(2020/08/10)
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- Method for preparation of quinoline compounds
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The invention discloses a green preparation method of quinoline compounds. According to the method, cheap and easily available copper salt and N-hydroxyphthalimide are used as catalysts, oxygen is used as an oxidizing agent, oxidation of tetrahydroquinoline compounds is performed in an organic solvent, and synthesis of quinoline compounds is realized. The method has the advantages of simple reaction operation, low reaction cost, high yield, low metal pollution and the like.
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Paragraph 0064-0066
(2020/11/12)
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- CONVERSION OF TETRAHYDROQUINOLINE DERIVATIVES TO QUINOLINE USING AZOCOMPOUND
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The present invention relates to a method of converting tetrahydroquinoline derivatives into quinoline using an azo compound and, more specifically, to a conversion method which is performed in a deuterium chloroform (CDCl_3) or chloroform (CHCl_3) solution including dialkyl azodicarboxylate, which is a method of producing quinoline through a dehydrogenation reaction of 1,2,3,4-tetrahydroquinoline. According to the present invention, a dehydrogenation reaction rate is dependent on the electronic and steric properties of used dialkyl azodicarboxylate; and chloroform shows better results than other substances in solvents screened with diethyl azodicarboxylate. Various types of 1,2,3,4-tetrahydroquinoline undergo the dehydration reaction of the present invention to produce the corresponding quinoline in a yield of at least 90%; and diethyl hydrazo dicarboxylate, which is a reduced form of diethyl azodicarboxylate, is readily separated and recyclable.COPYRIGHT KIPO 2020
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Paragraph 0041-0042; 0071; 0112-0116
(2020/03/10)
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- Corrigendum: Organo-Photoredox Catalyzed Oxidative Dehydrogenation of N-Heterocycles (Chemistry - A European Journal, (2017), 23, 57, (14167-14172), 10.1002/chem.201703642)
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The authors have been alerted to an error that was unfortunately missed at the time of publication. Table was duplicated with Table 4. The correct version of Table 2 is shown below. The authors apologise for any inconvenience caused. Organo-photoredox catalyzed oxidative dehydrogenation of tetrahydroquinolines (THQ).[a,b] (Table presented.) [a] Reaction conditions: 1 (0.5 mmol), rose bengal (1.0 mol %), N,N-dimethylacetamide (2.0 mL), open air atmosphere under visible-light irradiation at room temperature for 24 h. [b] Isolated yields. [c] 0.1 mol % of photoredox catalyst for 28 h.
- Sahoo, Manoj K.,Jaiswal, Garima,Rana, Jagannath,Balaraman, Ekambaram
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p. 7038 - 7038
(2019/05/17)
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- A Reusable Cobalt Catalyst for Reversible Acceptorless Dehydrogenation and Hydrogenation of N-Heterocycles
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The development of robust catalytic systems based on base-metals for reversible acceptorless dehydrogenation (ADH) and hydrogenation of feedstock chemicals is very important in the context of ‘hydrogen storage’. Herein, we report a highly efficient reusable cobalt-based heterogeneous catalyst for reversible dehydrogenation and hydrogenation of N-heterocycles. Both the ADH and the hydrogenation processes operate under mild, benign conditions.
- Jaiswal, Garima,Subaramanian, Murugan,Sahoo, Manoj K.,Balaraman, Ekambaram
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p. 2449 - 2457
(2019/05/10)
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- Room temperature catalytic dehydrogenation of cyclic amines with the liberation of H2 using water as a solvent
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Catalytic dehydrogenation of cyclic amines, in particular partially saturated N-heterocycles to N-heterocyclic arenes, with the removal of molecular hydrogen as the sole byproduct in water is reported. This dehydrogenation reaction proceeds smoothly under very mild and benign conditions and operates at room temperature. This distinctive reactivity has been achieved under dual catalytic conditions by merging the visible-light active [Ru(bpy)3]2+ as the photoredox catalyst and a newly synthesized cobalt complex as the proton-reduction catalyst. A detailed mechanistic study (control experiments, electrochemical studies, UV-visible experiments) is presented for the present dual catalysis.
- Sahoo, Manoj K.,Balaraman, Ekambaram
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supporting information
p. 2119 - 2128
(2019/04/26)
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- Nitrogen-coordinated cobalt nanocrystals for oxidative dehydrogenation and hydrogenation of N-heterocycles
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To endow non-noble metals with the high catalytic activity that is typically exhibited by noble metals is the central yet challenging aim for substituting noble metals. In this regard, by exploiting the coordination effect of nitrogen, we prepared cobalt nanocrystals stabilized by nitrogen-doped graphitized carbon (Co NCs/N-C). The obtained Co NC/N-C catalyst showed extraordinary performances toward both oxidative dehydrogenation of N-heterocycles and its reverse hydrogenation process under extremely mild conditions. A nearly quantitative conversion could be achieved for oxidative dehydrogenation even at room temperature (25 °C), for which the coordination effect of nitrogen is responsible: the interaction of Co-N induces a partial positive charge on the Co surface, thereby promoting the reaction. In contrast, cobalt nanocrystals supported by pristine carbon (Co NCs/C) proved to be inactive for oxidative dehydrogenation, owing to the lack of nitrogen. Moreover, in Co NCs/N-C, the N-doped graphitized carbon formed a protective layer for Co NCs, which preserved the active valence of Co species and prevented the catalyst from leaching. It was found that the catalyst still retained its excellent catalytic activity after five regeneration cycles; in comparison, its cobaltous oxide counterpart (CoOx/N-C) was barely active. As for the mechanism, electron paramagnetic resonance (EPR) analysis revealed the formation of superoxide anion radicals during the dehydrogenation process. Interestingly, the pressure of feed hydrogen had little effect on the hydrogenation process. Our Co NC/N-C catalyst is capable of activating molecular oxygen and hydrogen as effectively as noble metals; the coordination effect of nitrogen and the protection by the carbon layer in combination confer tremendous potential on the Co NCs/N-C for substituting noble-metal-based catalysts and soluble catalysts for homogeneous reactions.
- Wu, Yue,Chen, Zheng,Cheong, Weng-Chon,Zhang, Chao,Zheng, Lirong,Yan, Wensheng,Yu, Rong,Chen, Chen,Li, Yadong
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p. 5345 - 5352
(2019/05/29)
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- Visible-Light Photocatalyzed Deoxygenation of N-Heterocyclic N-Oxides
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A scalable and operationally simple method is described that allows for the chemoselective deoxygenation of a wide range of N-heterocyclic N-oxides (a total of 36 examples). This visible-light-induced protocol features the use of only commercially available reagents, room-temperature conditions, and unprecedented chemoselective removal of the oxygen atom in a quinoline N-oxide in the presence of a pyridine N-oxide in the same molecule through the judicious selection of a photocatalyst.
- Kim, Kyu Dong,Lee, Jun Hee
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supporting information
p. 7712 - 7716
(2019/01/03)
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- Activation of 6-bromoquinoline by nitration: Synthesis of morpholinyl and piperazinyl quinolones
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Quinoline forms the key skeletal component of a number of important natural products and pharmacologically-Active compounds. Despite a tremendous amount of research pertaining to the derivatization of quinoline, very few general synthetic routes are described in the literature starting from quinoline or tetrahydroquinoline. A simple and convenient method for the polyfunctionalization of quinolines via nitration of bromoquinolines has been developed. This method represents a new synthetic approach to convert brominated nitroquinoline derivatives into useful cyclic amines via nucleophilic-substitution (SNAr) reaction. Formula parented.
- ?akmak, Osman,?kten, Salih,Alimli, Dilek,Saddiqa, Aisha,Ersanli, Cem C?neyt
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p. 362 - 374
(2018/07/05)
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- Efficient dehydrogenation of 1,2,3,4-tetrahydroquinolines mediated by dialkyl azodicarboxylates
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Various dialkyl azodicarboxylates were investigated for the dehydrogenation of 1,2,3,4-tetrahydroquinolines to quinolines. The dehydrogenation rates varied according to the electronic and steric nature of the used dialkyl azodicarboxylates. Among solvents screened with diethyl azodicarboxylate, chloroform exhibited superior results to others. A variety of 1,2,3,4-tetrahydroquinolines underwent the present dehydrogenation to produce the corresponding quinolines. Diethyl hydrazodicarboxylate, which is a reduced species of diethyl azodicarboxylate, was easily separated for recycle.
- Bang, Saet Byeol,Kim, Jinho
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supporting information
p. 1291 - 1298
(2018/04/05)
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- Aerobic oxidative dehydrogenation of N-heterocycles catalyzed by cobalt porphyrin
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An efficient catalytic procedure has been developed for the aerobic oxidative dehydrogenation of N-heterocycles by cobalt porphyrin in the absence of any additives. The catalytic system could tolerate various 1,2,3,4-tetrahydroquinoline derivatives and some other N-heterocycles. The corresponding N-heteroaromatics could be obtained in 59–86% yields. The mechanism investigation suggested that the aerobic oxidative dehydrogenation might proceed with imine intermediate through radical paths.
- Zhou, Weiyou,Chen, Dongwei,Sun, Fu'an,Qian, Junfeng,He, Mingyang,Chen, Qun
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supporting information
p. 949 - 953
(2018/02/09)
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- Gold(0) catalyzed dehydrogenation of N-heterocycles
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Gold nanoclusters are good catalyst precursors for the catalytic dehydrogenation of indolines, tetrahydroquinazolines, and related N-heterocycles. The catalytically active species is presumably Au(0) nanoparticles.
- Kumaran, Elumalai,Leong, Weng Kee
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supporting information
p. 3958 - 3960
(2018/10/02)
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- Electrochemical Acceptorless Dehydrogenation of N-Heterocycles Utilizing TEMPO as Organo-Electrocatalyst
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Catalytic acceptorless dehydrogenation (CAD) has been a basically important organic transformation to ubiquitous unsaturated compounds without the usage of a sacrificial hydrogen acceptor. In this work, we successfully developed the first electrochemical acceptorless dehydrogenation (ECAD) of N-heterocycles using TEMPO as the organo-electrocatalyst. We have achieved the catalytic dehydrogenation of N-heterocycles in an anode and the release of H2 in a cathode using an undivided-cell system. A variety of six-membered and five-membered nitrogen-heteroarenes can be synthesized in good yields in this system. In addition, this protocol can also be used in the application of important molecular synthesis. Our electrochemical strategy provides a mild and metal-free route for (hetero)aromatic compounds synthesis via the CAD strategy.
- Wu, Yong,Yi, Hong,Lei, Aiwen
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p. 1192 - 1196
(2018/02/14)
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- Oxidation Potential Tunable Organic Molecules and Their Catalytic Application to Aerobic Dehydrogenation of Tetrahydroquinolines
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In this work, oxidation potential tunable organic molecules, alkyl 2-phenyl hydrazocarboxylates, were disclosed. The exquisite tuning of their oxidation potentials facilitated a catalytic dehydrogenation of 1,2,3,4-tetrahydroquinolines in the presence of Mn(Pc) and O2.
- Jung, Dahyeon,Jang, Seol Heui,Yim, Taeeun,Kim, Jinho
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supporting information
p. 6436 - 6439
(2018/10/15)
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- Method for compounding quinoline compound in manner of oxidative dehydrogenation of tetrahydroquinoline compound through visible light catalysis
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The invention discloses a method for compounding a quinoline compound in the manner of oxidative dehydrogenation of a tetrahydroquinoline compound through visible light catalysis. The method comprises the following steps: utilizing oxygen to replace peroxide as an oxidizing agent; taking polysubstituted BODIPY organic compound as a photocatalyst; catalyzing the oxidative dehydrogenation of 1,2,3,4-tetrahydroquinoline compound and compounding the quinoline compound. Compared with the present compounding method, the method has the advantages of mild reaction condition, metal-free photocatalyst used in the reaction, less dosage of the catalyst, high catalytic efficiency, stabilization, high efficiency, simple operation, environmental protection, high conversion rate of products and excellent selectivity.
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Paragraph 0018; 0019; 0020-0023; 0030-0050; 0099-0102
(2017/10/07)
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- Regioselective bromination: Synthesis of brominated methoxyquinolines
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Simple synthetic methods are described for the synthesis of valuable polyfunctional brominated methoxyquinolines 10–13, 20–21, and 24–25. Three regioselective routes are described for convenient preparation of brominated methoxyquinolines at the C-2, C-3,
- ?akmak, Osman,?kten, Salih
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p. 5389 - 5396
(2017/08/11)
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- Organo-Photoredox Catalyzed Oxidative Dehydrogenation of N-Heterocycles
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We report here for the first time the catalytic oxidative dehydrogenation of N-heterocycles by a visible-light organo-photoredox catalyst with low catalyst loading (0.1–1 mol %). The reaction proceeds efficiently under base- and additive-free conditions with ambient air at room temperature. The utility of this benign approach is demonstrated by the synthesis of various pharmaceutically relevant N-heteroarenes such as quinoline, quinoxaline, quinazoline, acridine, and indole.
- Sahoo, Manoj K.,Jaiswal, Garima,Rana, Jagannath,Balaraman, Ekambaram
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supporting information
p. 14167 - 14172
(2017/10/16)
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- Acceptorless Dehydrogenation of N-Heterocycles by Merging Visible-Light Photoredox Catalysis and Cobalt Catalysis
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Herein, the first acceptorless dehydrogenation of tetrahydroquinolines (THQs), indolines, and other related N-heterocycles, by merging visible-light photoredox catalysis and cobalt catalysis at ambient temperature, is described. The potential applications to organic transformations and hydrogen-storage materials are demonstrated. Primary mechanistic investigations indicate that the catalytic cycle occurs predominantly by an oxidative quenching pathway.
- He, Ke-Han,Tan, Fang-Fang,Zhou, Chao-Zheng,Zhou, Gui-Jiang,Yang, Xiao-Long,Li, Yang
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supporting information
p. 3080 - 3084
(2017/03/14)
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- Method for catalyzing nitrogen heterocyclic ring compound for oxidative dehydrogenation with hydrotalcite-like material
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The invention relates to a method for catalyzing a nitrogen heterocyclic ring compound for oxidative dehydrogenation with a hydrotalcite-like material, and belongs to the application aspect of a hydrotalcite-like component. The hydrotalcite-like component can be expressed as: A-MxM-LDHs (A=OH or CO3; M=Ni, Co, Cu, Mg or Zn; M=Fe, Mn, Al; M/M=(2 to 4)). Under existence of the catalyst and without adding any additives, oxidative dehydrogenation reaction is performed on the heterocyclic ring compound under a mild condition to prepare a corresponding aromatic compound. According to the method provided by the invention, the hydrotalcite-like material is based on non-noble metal, can be synthesized largely, and can be recycled; the method has the advantages of being high in catalytic reaction efficiency, mild in reaction condition, low in cost, easy to industrialize and the like.
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Paragraph 0048; 0049; 0050; 0051; 0052
(2017/10/27)
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- Cu-Catalyzed Aerobic Oxidation of Di-tert-butyl Hydrazodicarboxylate to Di-tert-butyl Azodicarboxylate and Its Application on Dehydrogenation of 1,2,3,4-Tetrahydroquinolines under Mild Conditions
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A new class of co-catalytic system was developed with homogeneous CuI and di-tert-butyl azodicarboxylate for aerobic dehydrogenation of 1,2,3,4-tetrahydroquinolines under mild conditions. The developed co-catalytic system is consisting of di-tert-butyl azodicarboxylate-mediated dehydrogenation of 1,2,3,4-tetrahydroquinoline and aerobic oxidative regeneration of di-tert-butyl azodicarboxylate from di-tert-butyl hydrazodicarboxylate using molecular oxygen as a terminal oxidant. A variety of quinolines were efficiently synthesized by the developed Cu and di-tert-butyl azodicarboxylate co-catalytic system.
- Jung, Dahyeon,Kim, Min Hye,Kim, Jinho
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p. 6300 - 6303
(2016/12/23)
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- A Convenient Procedure for the Oxidative Dehydrogenation of N-Heterocycles Catalyzed by FeCl2/DMSO
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A convenient catalytic procedure has been developed for the oxidative dehydrogenations of N-heterocycles. Combining catalytic FeCl2 with DMSO yields a catalyst that promotes the dehydrogenation of tetrahydroquinolines and related heterocycles under 1 bar of O2, affording the corresponding N-heteroaromatic products in moderate yields.
- Zhou, Weiyou,Taboonpong, Piyada,Aboo, Ahmed Hamdoon,Zhang, Lingjuan,Jiang, Jun,Xiao, Jianliang
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supporting information
p. 1806 - 1809
(2016/07/16)
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- Synthesis of quinolines from glycerol over tungstic acid functionalized mesoporous KIT-6 catalyst in aqueous medium
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Mesoporous tungstic acid functionalized KIT-6 has been synthesized through a condensation of (3-chloropropyl) triethoxysilane and Si-KIT-6 followed by substitution of chloromethylation functionalized KIT-6 by sodium tungstate dihydrate. The synthesized tungstic acid functionalized KIT-6 (W-KIT-6) was characterized by low and wide angle X-ray diffraction analysis (XRD), N2 adsorption-desorption isotherm, scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), NH3-temperature programmed desorption (NH3-TPD), 13C CP/MAS NMR spectrum and FT-IR analysis. The functionalized KIT-6 posses surface area of 663 m2/g with corresponding pore size 6.3 nm and pore volume 0.65 cm3/g. The catalytic activity of W-KIT-6 nanoparticles evaluated in the Skraup synthesis of quinoline and its derivatives using water as solvent, the results show the target compound was obtained as 89% yield with complete conversion of glycerol (100%) under the reaction conditions of 200°C for 3 h. The catalyst has been recycled for five times without significant loss in catalytic activity.
- Udayakumar,Pandurangan
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p. 919 - 928
(2017/08/04)
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- Preparation method for 6-bromine quinoline
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The invention discloses a preparation method for 6-bromine quinoline and relates to the technical field of organic synthesis. A catalyst and parabromoaniline are added into dilute sulphuric acid, the temperature of 140-145 DEG C is controlled, glycerol is dropwise added, and after dropping adding, 140-145 DEG C dehydration reaction is conducted for 3 h; the reaction liquid is dropwise added into ice water, then, ammonium hydroxide is added dropwise, and pH of a system is adjusted; methylbenzene is used for extracting the reaction liquid, methylbenzene-phase concentration is 150-155 DEG C/15 mmHg, the obtained crude product is distilled, and then the product 6-bromine quinoline is obtained. A catalytic number of catalysts are adopted as the reaction raw materials, the price of the catalyst is lower than that of other oxidizing agents, waste water and exhaust gas are treated easily, and no waste residue is produced. Finished raw material products are low in price, the recovery rate of adopted solvent is high, one-pot method operation is easy and convenient, and the yield is greatly increased.
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Paragraph 0026-0027
(2018/02/04)
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- Catalytic Aerobic Dehydrogenation of Nitrogen Heterocycles Using Heterogeneous Cobalt Oxide Supported on Nitrogen-Doped Carbon
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Dehydrogenation of (partially) saturated heterocycles provides an important route to heteroaromatic compounds. A heterogeneous cobalt oxide catalyst, previously employed for aerobic oxidation of alcohols and amines, is shown to be effective for aerobic dehydrogenation of various 1,2,3,4-tetrahydroquinolines to the corresponding quinolines. The reactions proceed in good yields under mild conditions. Other N-heterocycles are also successfully oxidized to their aromatic counterparts.
- Iosub, Andrei V.,Stahl, Shannon S.
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supporting information
p. 4404 - 4407
(2015/09/28)
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- Synthesis and Characterization of Iron-Nitrogen-Doped Graphene/Core-Shell Catalysts: Efficient Oxidative Dehydrogenation of N-Heterocycles
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An important goal for nanocatalysis is the development of flexible and efficient methods for preparing active and stable core-shell catalysts. In this respect, we present the synthesis and characterization of iron oxides surrounded by nitrogen-doped-graphene shells immobilized on carbon support (labeled FeOx@NGr-C). Active catalytic materials are obtained in a simple, scalable and two-step method via pyrolysis of iron acetate and phenanthroline and subsequent selective leaching. The optimized FeOx@NGr-C catalyst showed high activity in oxidative dehydrogenations of several N-heterocycles. The utility of this benign methodology is demonstrated by the synthesis of pharmaceutically relevant quinolines. In addition, mechanistic studies prove that the reaction progresses via superoxide radical anions (·O2-).
- Cui, Xinjiang,Li, Yuehui,Bachmann, Stephan,Scalone, Michelangelo,Surkus, Annette-Enrica,Junge, Kathrin,Topf, Christoph,Beller, Matthias
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supporting information
p. 10652 - 10658
(2015/09/28)
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- One-pot synthesis of N-aryl propargylamine from aromatic boronic acid, aqueous ammonia, and propargyl bromide under microwave-assisted conditions
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A facile, one-pot synthesis of N-aryl propargylamine from aromatic boronic acid, aqueous ammonia, and propargyl bromide has been achieved under microwave-assisted conditions. The reactions can be smoothly completed within a total 10 min through a two-step procedure, including copper-catalyzed coupling of aromatic boronic acids with aqueous ammonia and following propargylation by propargyl bromide.
- Jiang, Yu-Bo,Zhang, Wen-Sheng,Cheng, Hui-Ling,Liu, Yu-Qi,Yang, Rui
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p. 779 - 782
(2014/06/09)
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- Synthesis of quinolines and fused pyridocoumarins from N-propargylanilines or propargylaminocoumarins by catalysis with gold nanoparticles supported on TiO2
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[5,6]-Fused pyridocoumarins are prepared under mild conditions in excellent yields through the activation of the triple bond of 6-propargylaminocoumarins by gold nanoparticles supported on TiO2. The analogous reaction of N-propargylanilines with Au/TiO2 or Au/Al2O3 resulted in the formation of quinolines.
- Symeonidis, Theodoros S.,Lykakis, Ioannis N.,Litinas, Konstantinos E.
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p. 4612 - 4616
(2013/06/26)
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- Ruthenium-catalyzed transformation of aryl and alkenyl triflates to halides
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Aryl triflates were transformed to aryl bromides/iodides simply by treating them with LiBr/NaI and [Cp*Ru(MeCN)3]OTf. The ruthenium complex also catalyzed the transformation of alkenyl sulfonates and phosphates to alkenyl halides under mild conditions. Aryl and alkenyl triflates undergo oxidative addition to a ruthenium(II) complex to form η'1- arylruthenium and 1-ruthenacyclopropene intermediates, respectively, which are transformed to the corresponding halides.
- Imazaki, Yusuke,Shirakawa, Eiji,Ueno, Ryota,Hayashi, Tamio
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supporting information
p. 14760 - 14763
(2012/11/07)
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- HETEROCYCLIC COMPOUNDS FOR THE INHIBITION OF PASK
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Disclosed herein are new heterocyclic compounds and compositions and their application as pharmaceuticals for the treatment of disease. Methods of inhibiting PAS Kinase (PASK) activity in a human or animal subject are also provided for the treatment of diseases such as diabetes mellitus.
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Page/Page column 90
(2012/11/08)
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- An improved palladium-catalyzed conversion of aryl and vinyl triflates to bromides and chlorides
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A facile Pd-catalyzed conversion of aryl and vinyl triflates to aryl and vinyl halides (bromides and chlorides) is described. This method allows convenient access to a variety of aryl, heteroaryl, and vinyl halides in good to excellent yields and with greatly simplified conditions relative to our previous report.
- Pan, Jun,Wang, Xinyan,Zhang, Yong,Buchwald, Stephen L.
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supporting information; experimental part
p. 4974 - 4976
(2011/11/06)
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- Palladium-catalyzed conversion of aryl and vinyl triflates to bromides and chlorides
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The palladium-catalyzed conversion of aryl and vinyl triflates to aryl and vinyl halides (bromides and chlorides) has been developed using dialkylbiaryl phosphine ligands. A variety of aryl, heteroaryl, and vinyl halides can be prepared via this method in
- Shen, Xiaoqiang,Hyde, Alan M.,Buchwald, Stephen L.
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supporting information; experimental part
p. 14076 - 14078
(2011/01/10)
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- Efficient and selective synthesis of quinoline derivatives
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The bromination reaction of 1,2,3,4-tetrahydroquinoline (7) was investigated by NBS and molecular bromine. One-pot synthesis is described for synthetically valuable 4,6,8-tribromoquinoline (3) and 6,8-dibromo-1,2,3,4-tetrahydroquinoline (6) on bromination
- Sahin, Ayse,Cakmak, Osman,Demirtas, Ibrahim,Okten, Salih,Tutar, Ahmet
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p. 10068 - 10074
(2008/12/22)
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- SUBSTITUTED 1-PROPIOLYLPIPERAZINES HAVING AN AFFINITY FOR THE MGLUR5 RECEPTOR IN ORDER TO TREAT PAINFUL CONDITIONS
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The invention relates to substituted 1-propiolylpiperazines according to formula (I), to a method for the production thereof, medicaments containing said compounds and to the use thereof in the production of medicaments. In formula (I), X represents N or C-R2 and n corresponds to a value between 0-8.
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Page/Page column 96
(2010/02/15)
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- A practical route to quinolines from anilines
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A practical route to quinoline from anilines through acid-mediated cyclization of 3-(N-aryl-N-sulfonylamino)propionaldehydes has been developed. Treatment of the cyclization products, dihydroquinoline intermediates with KOH in DMSO leads to substituted quinolines.
- Tokuyama, Hidetoshi,Sato, Masashi,Ueda, Toshihiro,Fukuyama, Tohru
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p. 105 - 108
(2007/10/03)
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