- Aryl or heteroaryl methoxylation reaction method
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The invention discloses an aryl or heteroaryl methoxylation reaction method. The method comprises the following steps: preparing a substrate. The coupling agent, ligand, solvent, catalyst and base are mixed homogeneously in an inert gas to give the aryl or heteroaryl methoxy compounds. Compared with a methoxylation reaction method in the prior art, the method has the advantages that the reaction system conditions are mild, the usage amount of the catalyst and the ligand is low to 5% of the amount of the substrate material, and the catalytic efficiency is improved. The method has better compatibility to different substrate expansion and discovery of aryl halides or heteroaryl halides with different functional groups. The yield of aryl or heteroaryl methoxy compounds prepared by the method disclosed by the invention is 36% - 89%.
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Paragraph 0106-0112
(2021/11/21)
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- Copper-Catalyzed Methoxylation of Aryl Bromides with 9-BBN-OMe
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A Cu-catalyzed cross-coupling reaction between aryl bromides and 9-BBN-OMe to provide aryl methyl ethers under mild conditions is reported. The oxalamide ligand BHMPO plays a key role in the transformation. Various functional groups on bromobenzenes are well tolerated, providing the desired anisole products in moderate to high yields.
- Li, Chen,Song, Zhi-Qiang,Wang, Dong-Hui,Wang, Jing-Ru
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supporting information
p. 8450 - 8454
(2021/11/17)
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- B(C6F5)3-Catalyzed Hydrosilylation of Vinylcyclopropanes
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A hydrosilylation of vinylcyclopropanes (VCPs) catalyzed by the strong boron Lewis acid B(C6F5)3 is reported. For the majority of VCPs, little or no ring opening of the cyclopropyl unit is observed. Conversely, for VCPs with bulky R groups, such as ortho-substituted aryl rings or branched alkyl residues, ring opening is the exclusive reaction pathway. This finding is explained by the thwarted hydride delivery to a sterically shielded, β-silicon-stabilized cyclopropylcarbinyl cation intermediate.
- He, Tao,Long, Peng-Wei,Oestreich, Martin
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supporting information
p. 7383 - 7386
(2020/10/12)
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- Electrochemical [4+2] Annulation-Rearrangement-Aromatization of Styrenes: Synthesis of Naphthalene Derivatives
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We report the first electrochemical strategy to synthesize functionalized naphthalene derivatives through [4+2] annulation—rearrangement–aromatization from styrenes under mild conditions. The electrolysis does not require metals, oxidants and high valence substrates, indicating the atom and step-economy ideals. The dehydrodimer produced through [4+2] cycloaddition of 4-methoxy α-methyl styrene is isolated and proved to be the key intermediate for the following oxydehydrogenation to form carbon cation, which undergoes rearrangement–aromatization to afford the final products. This reaction represents a powerful access to construct multi-substituted naphthalene blocks in a single step.
- Ma, Yueyue,Lv, Jufeng,Liu, Chengyu,Yao, Xiantong,Yan, Guoming,Yu, Wei,Ye, Jinxing
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supporting information
p. 6756 - 6760
(2019/04/17)
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- Hydrogen bond donor solvents enabled metal and halogen-free Friedel–Crafts acylations with virtually no waste stream
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We have developed a metal and halogen-free Friedel–Crafts acylation protocol with virtually no waste stream generation. We propose a hydrogen bonding donor solvent will form a hydrogen bonding network and may provide significant rate enhancement for Friedel–Crafts reactions. Trifluoroacetic acid is one of the strongest H-bond donor solvents, which is also volatile and can be easily recovered by distillation without need for reaction workup. Our protocol is a ‘green’ Friedel–Crafts acylation process: 1) the catalyst can be recovered and reused; 2) using halogen free starting material (carboxylic acids anhydride or carboxylic acids); 3) no need for aqueous reaction work-up; 4) minimum or no waste steam generation.
- Liu, Guangchang,Xu, Bo
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supporting information
p. 869 - 872
(2018/02/09)
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- Generation of Aryl and Heteroaryl Magnesium Reagents in Toluene by Br/Mg or Cl/Mg Exchange
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The alkylmagnesium alkoxide sBuMgOR?LiOR (R=2-ethylhexyl), which was prepared as a 1.5 m solution in toluene, undergoes very fast Br/Mg exchange with aryl and heteroaryl bromides, producing aryl and heteroaryl magnesium alkoxides (ArMgOR?LiOR) in toluene. These Grignard reagents react with a broad range of electrophiles, including aldehydes, ketones, allyl bromides, acyl chlorides, epoxides, and aziridines, in good yields. Remarkably, the related reagent sBu2Mg?2 LiOR (R=2-ethylhexyl) undergoes Cl/Mg exchange with various electron-rich aryl chlorides in toluene, producing diorganomagnesium species of type Ar2Mg?2 LiOR, which react well with aldehydes and allyl bromides.
- Ziegler, Dorothée S.,Karaghiosoff, Konstantin,Knochel, Paul
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supporting information
p. 6701 - 6704
(2018/05/05)
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- Mild Ring Contractions of Cyclobutanols to Cyclopropyl Ketones via Hypervalent Iodine Oxidation
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An iodine-mediated oxidative ring contraction of cyclobutanols has been developed. The reaction allows the synthesis of a wide range of aryl cyclopropyl ketones under mild and eco-friendly conditions. A variety of functional groups including aromatic or alkyl halides, ethers, esters, ketones, alkenes, and even aldehydes are nicely tolerated in the reaction. This is in contrast with traditional synthetic approaches for which poor functional group tolerance is often a problem. The practicality of the method is also highlighted by the tunability of iodine oxidation system. Specifically, combining the iodine(III) reagent with an appropriate base allows the reaction to accommodate a range of challenging electron-rich arene substrates. The facile scalability of this reaction is also exhibited herein. (Figure presented.).
- Sun, Yan,Huang, Xin,Li, Xiaojin,Luo, Fan,Zhang, Lei,Chen, Mengyuan,Zheng, Shiya,Peng, Bo
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p. 1082 - 1087
(2018/01/27)
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- P -Selective (sp2)-C-H functionalization for an acylation/alkylation reaction using organic photoredox catalysis
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p-Selective (sp2)-C-H functionalization of electron rich arenes has been achieved for acylation and alkylation reactions, respectively, with acyl/alkylselenides by organic photoredox catalysis involving an interesting mechanistic pathway.
- Pandey, Ganesh,Tiwari, Sandip Kumar,Singh, Bhawana,Vanka, Kumar,Jain, Shailja
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supporting information
p. 12337 - 12340
(2017/11/20)
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- Another Role of Copper in the SimmonsSmith Reaction: Copper-catalyzed Nucleophilic Michael-type Cyclopropanation of a,β-Unsaturated Ketones
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Cyclopropanation was performed using the Furukawa procedure with CH2I2/Et2Zn and a,β-unsaturated ketones. The reaction was performed in the presence of a copper salt. The reactivity was highly dependent on the substrate structure, and cyclopropanated products were obtained in better yields than those achieved using the original SimmonsSmith conditions with a ZnCu couple in some cases. Stereospecificity was observed in a certain case; however, the synthesis of an asymmetric version with a chiral ligand was not successful.
- Fujii, Kanami,Misaki, Tomonori,Sugimura, Takashi
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p. 634 - 636
(2014/05/20)
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- Catalytic Friedel-Crafts acylation: Magnetic nanopowder CuFe 2O4 as an efficient and magnetically separable catalyst
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Catalytic regioselective Friedel-Crafts acylation of an array of anisoles/arenes with various acid chlorides using 5-20 mol % of magnetic nanopowder CuFe2O4 is reported. Unlike the conventional Friedel-Crafts reactions, which are catalyzed by moisture sensitive homogeneous catalysts/promoters, the nanopowder CuFe2O4 catalyst is moisture insensitive and the product/ketone-catalyst isolation is easily achieved using the magnetic properties of CuFe2O4.
- Parella, Ramarao,Naveen,Kumar, Amit,Babu, Srinivasarao Arulananda
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p. 1738 - 1742
(2013/03/28)
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- DFT evidence for a stepwise mechanism in the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals
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(Chemical Equation Presented) Hybrid DFT calculations of the potential energy surface (PES) relative to the O-neophyl rearrangement of a series of ring-substituted 1,1-diarylalkoxyl radicals have been carried out at the UB3LYP/6-31G(d) level of theory. On the basis of the computational data, the rearrangement can be described as a consecutive reaction of the type a ? b → c (see above graphic), and the steady-state approximation could be applied in all cases to the intermediate b. The first-order rearrangement rate constants [kobs = k1k2/(k-1 + k 2)] were thus obtained from the computed activation free-energies and were compared with the experimental rate constants measured previously in MeCN solution by laser flash photolysis. An excellent agreement is observed along the two series, which strongly supports the hypothesis that the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals proceeds through the formation of the reactive 1-oxaspiro [2,5]octadienyl radical intermediate. This is in contrast to previous hypotheses that involve either a long-lived intermediate or the absence of this intermediate along the reaction path. The calculated rearrangement free-energies decrease upon going from the methoxy-substituted radical (ΔG° = -16.4 kcal·mol-1) to the nitro-substituted one (ΔG° = -21.8 kcal·mol-1), which follows a trend that is similar to the one observed for the C Ar-O bond dissociation enthalpies (BDEs) of ring-substituted anisoles. This evidence indicates that in the O-neophyl rearrangement the effect of ring substituents on the strength of the newly formed CAr-O bond plays an important role.
- Bietti, Massimo,Ercolani, Gianfranco,Salamone, Michela
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p. 4515 - 4519
(2008/02/05)
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- Oxygen acidity of ring methoxylated 1,1-diarylalkanol radical cations bearing α-cyclopropyl groups. The competition between O-neophyl shift and C-cyclopropyl β-scission in the intermediate 1,1-diarylalkoxyl radicals
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A product and time-resolved kinetic study on the reactivity of the radical cations generated from cyclopropyl(4-methoxyphenyl)phenylmethanol (1) and cyclopropyl[bis(4-methoxyphenyl)]methanol (2) has been carried out in aqueous solution. In acidic solution, 1.+ and 2.+ display very low reactivities toward fragmentation, consistent with the presence of groups at Cα (aryl and cyclopropyl) that after Cα-C β bond cleavage would produce relatively unstable carbon-centered radicals. In basic solution, 1.+ and 2.+ display oxygen acidity, undergoing -OH-induced deprotonation from the α-OH group, leading to the corresponding 1,1-diarylalkoxyl radicals 1r. and 2r., respectively, as directly observed by time-resolved spectroscopy. The product distributions observed in the reactions of 1.+ and 2.+ under these conditions (cyclopropyl phenyl ketone, cyclopropyl(4-methoxyphenyl) ketone, and 4-methoxybenzophenone from 1.+; cyclopropyl(4-methoxyphenyl) ketone and 4,4′- dimethoxybenzophenone from 2.+) have been rationalized in terms of a water-induced competition between O-neophyl shift and C-cyclopropyl β-scission in the intermediate 1,1-diarylalkoxyl radicals 1r. and 2r..
- Bietti, Massimo,Fiorentini, Simone,Pato, Iria Perez,Salamone, Michela
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p. 3167 - 3175
(2007/10/03)
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- The effect of ring substitution on the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals. A product and time-resolved kinetic study
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A product and time-resolved kinetic study of the effect of ring substitution on the reactivity of 1,1-diarylalkoxyl radicals has been carried out. The radicals undergo an O-neophyl shift to give the isomeric 1-aryl-1-aryloxyalkyl radicals from which the corresponding aromatic ketones are formed. The rearrangement rate constants are influenced by ring substitution, increasing in the presence of electron-withdrawing substituents and decreasing in the presence of electron-donating ones. From the results of product and kinetic studies, the following migratory aptitudes have been obtained: 4-trifluoromethylphenyl > phenyl ? 4-methylphenyl > 4-methoxyphenyl. Excellent Hammett-type correlations between the σ+ substituent constants and both the visible absorption band maxima and the rearrangement rate constants have been obtained. The experimental results indicate that the rearrangement is governed by electronic effects in the starting 1,1-diarylalkoxyl radicals, whereas the stability of the rearranged carbon-centered radical plays a minor role, in line with a reactant-like transition state, strongly supporting the hypothesis that the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals proceeds through a concerted mechanism.
- Aureliano Antunes, Carla S.,Bietti, Massimo,Ercolani, Gianfranco,Lanzalunga, Osvaldo,Salamone, Michela
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p. 3884 - 3891
(2007/10/03)
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- Derivatised molecules for mass spectrometry
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Compounds of formula (IIa): are provided where:X is a group capable of being cleaved from the α-carbon atom to form an ion of formula (I')C is a carbon atom bearing a single positive charge or a single negative charge; The invention further provides compounds of formula (IIb): where:X is a counter-ion to C. The compounds of formula (IIa) and (IIb) may form ions of formula (I') by either cleaving the C-X bond between X and the α-carbon atoms in the case of the compounds of formula (IIa) or dissociating X in the case of compounds of formula (IIb).
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- Nickel catalyzed cross-coupling and amination reactions of aryl nitriles
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Aryl nitriles have been found to participate in cross-coupling and amination reactions via nickel-catalyzed activation of the C-CN bond. With the development of these synthetically useful transformations, aryl nitriles can now be considered along with ary
- Miller, Joseph A.,Dankwardt, John W.,Penney, Jonathan M.
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p. 1643 - 1648
(2007/10/03)
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- Nickel catalyzed cross-coupling of modified alkyl and alkenyl Grignard reagents with aryl- and heteroaryl nitriles: Activation of the C-CN bond
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The nickel catalyzed cross-coupling of alkyl and alkenyl Grignard reagents with aryl nitrile derivatives affords good yields of the corresponding aryl alkanes or aryl alkenes via activation of the C-CN bond. To prevent direct addition of the nucleophile to the nitrile group, the reactivity of the Grignard reagent was modulated by reaction with either LiOt-Bu or PhSLi prior to cross-coupling. The optimum catalyst was determined to be NiCl2(PMe3)2, which is a convenient air stable commercially available complex.
- Miller, Joseph A.,Dankwardt, John W.
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p. 1907 - 1910
(2007/10/03)
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- Laser flash photolysis study of arylcyclopropylcarbenium ions: Cation stabilizing abilities of cyclopropyl and phenyl groups
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Arylcyclopropylcarbenium ions, Ar(c-Pr)CH+, were generated as transient intermediates by laser flash photolysis (LFP) of trans-2,3-diphenylaziridinimines of aryl cyclopropyl ketones in 2,2,2-trifluoroethanol (TFE). The carbocations are thought to arise by way of diazo compounds and carbenes. Rate constants for the unimolecular decay in TFE and for the bimolecular reaction with methanol in TFE were obtained for Ar(c-Pr)CH+ and for analogous arylphenylcarbenium ions, ArPhCH+. Within these series, the cation stabilizing abilities of cyclopropyl and phenyl groups are found to be similar in magnitude. However, cyclopropyl responds more strongly than phenyl to increasing electron demand. Hence cyclopropyl is superior to phenyl in cation stabilizing ability for Ar = Ph but inferior to phenyl for Ar = 4-MeOC6H4.
- Kirmse, Wolfgang,Krzossa, Birgit,Steenken, Steen
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p. 7473 - 7477
(2007/10/03)
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- Synthesis of Alkyl and Aryl Cyclopropyl Ketones
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A series of cyclopropyl ketones are prepared by reactions of organometallic compounds with cyclopropanecarboxylic acid derivatives and also by cyclization of γ-chloro ketones.
- Matveeva,Kvasha,Kurts
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- Photochromic chromene compounds
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Described are a series of novel photochromic benzopyran and naphthopyran compounds substituted with (1) a cyclopropyl group and (2) a phenyl, substituted phenyl, or 5-member aromatic heterocyclic group at the 2-position of the benzopyran or naphthopyran ring. Also described are organic host materials that contain or that are coated with such compounds. Articles such as ophthalmic or plano lenses that incorporate the novel pyran compounds or combinations of the novel pyran compounds with other complementary photochromic compounds are described.
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- Precise Control of the Formation of a Covalent and an Ionic Bond in Carbocation-Carbanion Combination Reactions
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The electronic effect on the selectivity of covalent or ionic bond formation was examined for the reaction of Kuhn's anion 1(1-) (C67H39(1-); tris(7H-dibenzofluorenylidenemethyl)methide ion) and 1-aryl-2,3-dicyclopropylcyclopropenylium ions.The carbocation stability was progressively changed by varying the substituent on the phenyl ring, while the steric effect was kept essentially unchanged.The cations having the p-chlorophenyl (2a(1+)), phenyl (2b(1+)), m-methylphenyl (2c(1+)), or m,m'-dimethylphenyl (2d(1+)) group gave a covalent product, whereas a carbocation-carbanion salt was obtained from the cations having the p-methylphenyl (2e(1+)) or p-methoxyphenyl (2f(1+)) group.The reduction potentials Ered of the cations, as determined by cyclic voltammetry, showed that the formation of the covalent or ionic product is switched by a small difference in stability ( 0.4 kcal/mol) between 2d(1+) and 2e(1+).In chloroform, the salts 1(1-)2e(1+) and 1(1-)2f(1+) were transformed into covalent forms 1-2e and 1-2f, which can exist only in solution.When 1-(2a-d) and 1(1-)2e,f(1+) were dissolved in DMSO, equilibrium between a covalent compound and ions was established.A plot of the free energy of heterolysis ΔG0het for 1-(2a-f) against the Ered of the corresponding cations 2a-f(1+) showed that ΔG0het decreases as the cation is more stabilized.The heterolysis in DMSO was shown to be enhanced by ca. 13 kcal/mol both by the steric congestion in the covalent molecules and the stabilization of the cyclopropenylium ions by solvation.
- Takeuchi, Ken'ichi,Kitagawa, Toshikazu,Miyabo, Atsushi,Hori, Hideshi,Komatsu, Koichi
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p. 5802 - 5810
(2007/10/02)
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- Vinyl Cations. 41. Influence of 4-Aryl and 4-Alkyl Substituents on the ?-Route Solvolyses of Homopropargyl Esters
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The four 4-substituted-homopropargyl tosylates and triflates 6b-e (R=phenyl, p-tolyl, anisyl, and cyclopropyl) have been synthesized and solvolyzed under various conditions, as have 2-cyclopropyl-1-cyclobutenyl triflate (11-OTf) and nonaflate (11-ONf).In addition, the solvolyses of pent-3-yn-1-yl tosylate (6a-OTs, R=methyl) and triflate (prepared previously) are reported.The ratios of C-3 ring to C-4 ring 3 ring/C4ring)> products are recorded for the reactions in various solvents.As expected, ring closure (kΔ) increases and solvent displacement (kS, SN2) decreases with decreasing nucleophilicity of solvent.Temperature effects are noted for the sovolyses of tosylates 6a-e in 100percent TFE buffered with Na2CO3 in which kΔ increases with increasing temperature.The result is explained by decomposition of the intimate ion pair with temperature, whereupon elimination to the enyne becomes smaller and ring closure (kΔ) increases at the expense of elimination.The possibility of intervention of nonclassical vinyl cations is discussed, as are other mechanistic implications.
- Collins, Clair J.,Hanack, Michael,Stutz, Herbert,Auchter, Gerhard,Schoberth, Winfried
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p. 5260 - 5268
(2007/10/02)
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