- Synthesis and resolution of axially chiral C2-symmetric 1,1'-binaphthyl-substituted tetramethylethylenediamines
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The axially chiral TMEDA derivatives 1 and 2 in which tetramethylethylenediamine is substituted respectively by one and two 1,1'-binaphthyl units at their 2,2'-positions, are of interest as chiral catalysts. Experimental details of their preparation in enantiomerically pure form are given. Two different routes have been followed, involving alkylation of both N,N-dimethyl ethylenediamine and ethylenediamine by 2,2'-bis-(bromomethyl)-1,1'-binaphthyl either enantiomerically pure as prepared from resolved 1,1'-binaphthyl-2,2'-dicarboxylic acid or racemic, the resulting racemic diamines 1 and 2 being then resolved with dibenzoyl-tartaric acid.
- Mazaleyrat, Jean-Paul
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- Convenient Optical Resolution of Axially Chiral 1,1'-Binaphthyl-2,2'-dicarboxylic Acid
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Axially chiral 1,1'-binaphthyl-2,2'-dicarboxylic acid was conveniently resolved through its brucine salts in satisfactory yields.The resolved diacids were confirmed to be optically pure from high-performance liquid chromatographic analyses of the dimethyl esters derived from them on an optically active poly(diphenyl-2-pyridylmethyl methacrylate) column.
- Kanoh, Shigeyoshi,Hongoh, Yukihiko,Motoi, Masatoshi,Suda, Hiroshi
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- Facile synthesis of enantiopure 1,1'-binaphthyl-2,2'-dicarboxylic acid via lipase-catalyzed kinetic resolution
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Enantiopure 1,1'-binaphthyl-2,2'-dicarboxylic acids (R)-1 and (S)-1 have been synthesized through the lipase-catalyzed kinetic resolution of the racemic 2,2-bis(hydroxymethyl)-1,1'-binaphthyl (±)-2 and subsequent oxidation of the hydroxymethyl groups. (C) 2000 Elsevier Science Ltd.
- Furutani, Toshiyuki,Hatsuda, Masanori,Imashiro, Ritsuo,Seki, Masahiko
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- Practical synthesis of axially chiral dicarboxylates via Pd-catalyzed external-CO-free carbonylation
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We have developed a safe and practical synthetic method for preparing axially chiral diphenyl dicarboxylates using Pd- catalyzed external-CO-free carbonylation with phenyl formate as a CO surrogate. Optimized conditions consisted of axially chiral [1,1′-binaphthalene]-2,2′-diyl ditriflate and its congeners, each easily prepared from commercially available enantiomerically pure diols, Pd(OAc)2, 1,3-bis(diphenylphosphino)-propane, ethyldiisopropylamine, and no solvent. To demonstrate the potential utility of these products, this method was conducted on gram-scale and the phenyl ester products were converted to other useful compounds, and both processes were carried out without difficulty.
- Konishi, Hideyuki,Hoshino, Fumika,Manabe, Kei
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- Concise synthesis of binaphthol-derived chiral dicarboxylic acids
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Abstract 3,3'-Disubstituted 1,1'-binaphthyl-2,2'-dicarboxylic acids (1) were synthesized in three or four steps from commercially available BINOL via carbon dioxide fixation with organolithium to incorporate the carboxylic acid moieties, followed by either carboxylate-directed ortho-C-H arylation or Suzuki cross-coupling. This method provides easy access to various types of axiially chiral dicarboxylic acids, which should be useful for studies of chiral Br?nsted acid-catalyzed asymmetric reactions.
- Egami, Hiromichi,Sato, Kentaro,Asada, Junshi,Kawato, Yuji,Hamashima, Yoshitaka
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- Practical synthetic protocols of enantiopure 1,1′-binaphthyl-2, 2′-dicarboxylic acid and 2,2′-dicyano-1,1′-binaphthyl starting from optically active dibromide precursor
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Dilithiation of optically active 2,2′-dibromo-1,1 ′-binaphthyl 2 with t-BuLi followed by carboxylation of the resulting dilithio-intermediate 3 with CO2 gave optically active 1,1′-binaphthyl-2,2′-dicarboxylic acid 1, which was further transformed to its dicyano derivative 4. Both of these transformations were carried out in a one-pot operation and the products were obtained in excellent yields with no observable racemization.
- Hoshi, Takashi,Nozawa, Eiji,Katano, Masayoshi,Suzuki, Toshio,Hagiwara, Hisahiro
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- Stereoconservative cyanation of [1,1′-binaphthalene]-2,2′-dielectrophiles. An alternative approach to homochiral C2-symmetric [ 1,1′-binaphthalene]-2,2′-dicarbonitrile and its transformations
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The performed study on the cyanation of [1,1′-binaphthalene]-2,2′-diiodide and [1,1′-binaphthalene]-2,2′-diyl ditriflate showed reactions with zinc cyanide catalyzed by palladium phosphane complex in DMF to be the most effective procedures with almost com
- Kasak, Peter,Putala, Martin
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- Anomalous CD/UV exciton splitting of a binaphthyl derivative: The case of 2,2′-diiodo-1,1′-binaphthalene
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The UV and CD spectra of (R)-(+)-2,2′-diiodo-1,1′-binaphthalene show an unexpectedly large value of the wavelength splitting between the two main bands, resulting from the exciton coupling of 1Bb transitions. An hypothesis is proposed on transition moments directions, making it possible to relate quantitatively the observed splitting to the orthogonal arrangement found in the solid state and calculated for the structure in solution.
- Di Bari, Lorenzo,Pescitelli, Gennaro,Marchetti, Fabio,Salvadori, Piero
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- Embedding an allylmetal dimer in a chiral cavity: The unprecedented stereoselectivity of a twofold Wittig [1,2]-rearrangement
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After α,α'-dimetalation, both 2,2′-diallyloxy-1,1′-binaphthyl and 2,2′-di-2-methylallyloxy-1,1′-binaphthyl undergo the Wittig rearrangement with perfect diastereoselectivity. When racemic 1,1′-binaphthyl-2,2′-diol ("BINOL") is used as the starting material, it gives rise to a 1:1 mixture of antipodal stereoisomers, whereas enantiomerically pure (M)-2,2′-diallyloxy-1,1′-binaphthyl affords (M)-(S,S)-1,1-(1,1′-binaphthyl-2,2′-diyl)bis(2-propen-1-ol) as the sole product. The (M)-(S,S)/(P)-(R,R) mixture resulting from the rearrangement of racemic 2,2′-diallyloxy-1,1′-binaphthyl can be effectively subjected to a kinetic racemate resolution by applying the Sharpless-Katsuki asymmetric epoxidation. The single-sided Wittig rearrangement of 2-allyloxy-2′-propyloxy-1,1′-binaphthyl proceeds without any diastereoselectivity as this substrate can only be monometalated and hence is incapable of intramolecular aggregate formation which is instrumental for the observed stereoselectivity. Copyright
- Schlosser, Manfred,Bailly, Frederic
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- Convenient synthesis of 1,1'-binaphthyl-2,2'-dicarboxylic acid
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Two syntheses of 1,1'-binaphthyl-2,2'-dicarboxylic acid (4) in good yields are presented via the oxidation of the 2'-methyl substituent of isopropyl 2'-methyl-1,1'-binaphthyl-2-carboxylate (8), which is readily obtainable by the reaction of 2-methyl-1-naphthyl Grignard reagent 7 with isopropyl 1-isopropoxy-2-naphthoate (6).
- Oi,Matsunaga,Hattori,Miyano
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- A Practical Method for Optical Resolution of 1,1'-Binaphtyl-2,2'-dicarboxylic Acid via 1-Phenylethylamides
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Both enentiomers of 1,1'-binaphthyl-2,2'-dicarboxylic acid (100percent ee's by HPLC) were conveniently obtained in high yields (ca. 80percent of the theory) via fractional crystallization of the (S)-1-phenylethylamide diastereomers of the racemic acid followed by treatment with thionyl chloride and then alkaline hydrolysis
- Oi, Shuichi,Matsuzaka, Yutaka,Yamashita, Junzo,Miyano, Sotaro
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- Chiral Ligands in Hypervalent Iodine Compounds: Synthesis and Structures of Binaphthyl-Based λ3-Iodanes
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Several novel binaphthyl-based chiral hypervalent iodine(III) reagents have been prepared and structurally analysed. Various asymmetric oxidative reactions were applied to evaluate the reactivities and stereoselectivities of those reagents. Moderate to excellent yields were observed; however, very low stereoselectivities were obtained. NMR experiments indicated that these reagents are very easily hydrolysed in either chloroform or DMSO solvents leading to the limited stereoselectivities. It is concluded that the use of chiral ligands is an unsuccessful way to prepare efficient stereoselective iodine(III) reagents.
- Zhang, Huaiyuan,Cormanich, Rodrigo A.,Wirth, Thomas
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supporting information
(2021/12/22)
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- TRANSITION METAL COMPOUND FOR OLEFIN POLYMERIZATION CATALYST, OLEFIN POLYMERIZATION CATALYST COMPRISING SAME AND POLYOLEFIN POLYMERIZED USING SAME
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Provided is a transition metal compound, represented by chemical formula 1, for an olefin polymerization catalyst. The details of chemical formula 1 are the same as those defined in the specification.
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Paragraph 0050-0051
(2021/06/11)
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- Synthesis method of axially chiral dinaphthalene ligand precursor (s)-2,2'-dinaphthyl-1,1'-dicarboxylic acid
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The invention relates to the technical field of bromination, hydrolysis, oxidation and coupling reaction in organic synthesis, particularly a synthesis method of an axially chiral dinaphthalene ligand precursor (s)-2,2'-dinaphthyl-1,1'-dicarboxylic acid. The method comprises the following steps: synthesizing a compound 1-bromo-2-methylnaphthalene from an initial raw material 2-bromomethylnaphthalene, carrying out bromination, hydrolysis and oxidation on the 1-bromo-2-methylnaphthalene to obtain 1-bromo-2-naphthoic acid, generating an ester under the actions of methanol and thionyl chloride, protecting the carboxyl group, carrying out Ullmann reaction under the action of copper powder to perform coupling, carrying out hydrolysis to obtain 2,2'-dinaphthyl-1,1'-dicarboxylic acid, and finally, resolving to obtain the (s)-2,2'-dinaphthyl-1,1'-dicarboxylic acid. The method is simple to operate, and has the advantages of higher yield and favorable economical efficiency.
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- Design and synthesis of new stable fluorenyl-based radicals
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Organic neutral radicals have long fascinated chemists with a fundamental understanding of structure-reactivity relationships in organic reactions and with applications as new functional materials. However, the elusive nature of these radicals makes the synthesis, isolation, and characterization very challenging. In this work, the synthesis of three long-lived, fluorenyl-based radicals are reported. The geometry and electronic structures of these radicals were systematically investigated with a combination of various experimental methods, besides density functional theory (DFT) calculations, which include X-ray crystallographic analysis, electron spin resonance (ESR), electron nuclear double resonance (ENDOR), cyclic voltammetry, and UV-vis-NIR measurements. Their half-life periods (τ1/2) in air-saturated solution under ambient conditions were also determined. Surprisingly, all three radicals showed remarkable stabilities: τ1/2 = 7, 3.5, and 43 days.
- Tian, Yi,Uchida, Kazuyuki,Kurata, Hiroyuki,Hirao, Yasukazu,Nishiuchi, Tomohiko,Kubo, Takashi
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p. 12784 - 12793
(2015/02/19)
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- Enantiopure isoplagiochin C by directed deracemization through axis-to-axis chirality transfer
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Isoplagiochin C 1 was prepared for the first time in enantiopure form from synthetic racemic material, using a novel stereochemical concept. This macrocyclic bisbibenzyl contains two biaryl axes. Of these, axis A is configurationally stable by its fixation within the macrocyclic framework, while axis B is stereochemically unstable. By diesterification of rac-1 with enantiopure (P)-1,1′-binaphthyl-2,2′-dicarboxylic acid, axis B is locked in its P-configuration, thus allowing the resolution and separate saponification of dilactones (PA,PB,P)-3 and (M A,PB,P)-3 to give the pure enantiomers of 1. This concept permits recycling of any undesired enantiomer of 1 by thermal equilibration of the respective diastereomer of 3.
- Bringmann, Gerhard,Hager, Dominik,Schaumloeffel, Anu,Groh, Matthias,Speicher, Andreas
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p. 575 - 581
(2013/06/27)
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- In situ generation of hydroperoxide by oxidation of benzhydrols to benzophenones using sodium hydride under oxygen atmosphere: Use for the oxidative cleavage of cyclic 1,2-diketones to dicarboxylic acids
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A facile oxidative cleavage of cyclic 1,2-diketones 1 to dicarboxylic acids 3 with hydroperoxide generated in situ has been developed. In situ generation of hydroperoxide was effected by the oxidation of 4,4′-dichlorobenzhydrol 2f to 4,4′-dichlorobenzophenone 4f using sodium hydride under oxygen atmosphere.
- Kang, Sunhae,Lee, Soyoung,Jeon, Minju,Kim, Sun Min,Kim, Young Sug,Han, Hogyu,Yang, Jung Woon
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p. 373 - 376
(2013/02/23)
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- DIBENZO[C,G]FLUORENE COMPOUND AND ORGANIC LIGHT-EMITTING DEVICE USING SAME
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An organic light-emitting device is provided which efficiently emits light with high brightness and has durability. The organic light-emitting device includes a dibenzo[c,g]fluorene compound having two dibenzo[c,g]fluorene skeletons, and has an organic compound layer containing the dibenzo[c,g]fluorene compound.
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Page/Page column 11; 40-41
(2010/06/11)
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- DIBENZO[c,g]FLUORENE COMPOUND AND AN ORGANIC LIGHT-EMITTING DEVICE USING THE SAME
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An organic light-emitting device which has high emission efficiency and high durability even at low drive voltage is provided. An organic light-emitting device including an anode, a cathode, and an organic compound layer which is interposed between the anode and the cathode, wherein the organic compound layer include at least one dibenzo[c,g]fluorene compound represented by the following General Formula (1).
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Page/Page column 55-56
(2009/12/23)
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- A new synthetic route to enantiomerically pure axially chiral 2,2′-bipyridine N,N′-dioxides. Highly efficient catalysts for asymmetric allylation of aldehydes with allyl(trichloro)silanes
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New axially chiral 2,2′-bipyridine N,N′-dioxides 1 were obtained in an enantiomerically pure form by way of cyclic diesters 6 or 7 which were formed by the esterification of diols 2 with (R)-2,2′-bis(chlorocarbonyl)-1,1′-binaphthalene (5). Epimerization of the kinetic products at the ester formation (Rnap,Spyr)-6 to the thermodynamically stable isomers (Rnap,Rpyr)-7 was observed in refluxing toluene or in the presence of trifluoroacetic acid. One of the N,N′-dioxides 1a which is substituted with phenyl groups at the 6 and 6′ positions was found to be highly catalytically active and enantioselective for the asymmetric allylation of aldehydes with allyl(trichloro)silane giving homoallyl alcohols.
- Shimada, Toyoshi,Kina, Asato,Hayashi, Tamio
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p. 6329 - 6337
(2007/10/03)
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- A novel axially chiral 2,2′-bipyridine N,N′-dioxide. Its preparation and use for asymmetric allylation of aldehydes with allyl(trichloro)silane as a highly efficient catalyst
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(Matrix presented) New axially chiral 2,2′-bipyridine N,N′-dioxides were obtained by a new method that does not involve any procedures for the separation of enantiomers. One of the dioxides, (R)-3,3′-bis(hydroxymethyl)-6,6′-diphenyl-2,2′-bipyridine N,N′-dioxide, exhibited extremely high catalytic activity for the asymmetric allylation of aldehydes with allyl(trichloro)silane. The allylation of aromatic aldehydes proceeded in the presence of 0.01 or 0.1 mol % of the dioxide catalyst to give the corresponding homoallyl alcohols of up to 98% ee.
- Shimada, Toyoshi,Kina, Asato,Ikeda, Syushiro,Hayashi, Tamio
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p. 2799 - 2801
(2007/10/03)
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- A practical synthesis of C2-symmetric chiral binaphthyl ketone catalyst
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A practical synthesis of 11-membered C2-symmetric binaphthyl ketone (R)-1, a catalyst for asymmetric epoxidation, was developed. (±)-1,1'-Binaphthyl-2,2'-dicarboxylic acid [(±)-6] was efficiently resolved by (R)-(-)-1-cyclohexylethylamine to give (R)-6 in >99% ee and in 38% yield. Condensation of the acid chloride derived from (R)-6 with 1,3-dihydroxyacetone dimer at 60-70 °C provided the desired chiral ketone (R)-1 in 61-63% yield without need for high dilution techniques.
- Seki,Yamada,Kuroda,Imashiro,Shimizu
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p. 1677 - 1680
(2007/10/03)
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- Homochiral 2,2'-bis(oxazolyl)-1,1'-binaphthyls as ligands for copper(I)- catalyzed asymmetric cyclopropanation
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Homochiral 2,2'-bis[4-(alkyl)oxazol-2-yl]-1,1'-binaphthyls, which possess both binaphthyl axial chirality and carbon centred chirality, were prepared from 1,1'-binaphthyl-2,2'-dicarboxylic acid and 2-alkyl-2-aminoethanols in high yields. Asymmetric cyclopropanation of styrene with diazoacetates in the presence of 2 mol % of copper(I) triflate and (S)-2,2'-bis[(S)-4-(t- butyl)oxazol-2-yl]-1,1'-binaphthyl gave optically active 2- (phenyl)cyclopropane-carboxylates of up to 97% ee.
- Uozumi,Kyota,Kishi,Kitayama,Hayashi
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p. 1603 - 1606
(2007/10/03)
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- Enantioselective catalysis of the triplex diels-alder reaction: A study of scope and mechanism
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Irradiation of the chiral sensitizers 1,1-bis(2,4-dicyanonaphthalene) and 1,r-bis(2,10-dicyanoanthracene) catalyzes the triplex Diels-Alder reaction of trans-β-methylstyrene with 1,3-cyclohexadiene to form the [4 + 2] cycloadducts endo-trans-6-methyl-5-phenylbicyclo[2.2.2]oct-2-ene. When the sensitizer is optically active and the irradiation is performed at low temperature in ether or toluene solution, the [4 + 2] cycloadducts are formed enantioselectively. The mechanism of the enantioselective triplex Diels-Alder reaction was examined by chemical and spectroscopic means. Interaction of the chiral sensitizer with the prochiral styrene forms diastereomeric exciplexes. The equilibration of these exciplexes is fast at room temperature but not at low temperature. The exciplexes react with diene to form a triplex. This reaction leads to cycloadduct formation. Enantioselection is a consequence of different trapping efficiencies for the diastereomeric exciplexes by diene.
- Kim, Ji-In,Schuster, Gary B.
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p. 9309 - 9317
(2007/10/02)
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- Chiral Discrimination towards Racemic Alcohols through Host/Guest Clathrate Inclusion with Axially Chiral 1,1'-Binaphthyl-2,2'-dicarboxylic Acid
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Axially chiral 1,1'-binaphthyl-2,2'-dicarboxylic acid (1) was successfully utilised as a new type of chiral host molecule soluble in aqueous alkaline solution; 1-phenylalkan-1-ols were optically resolved by means of chiral host/guest chlatrate inclusion giving optical purities ranging from 18 to 90percent enantiomeric excess (e.e.) depending on the alkyl group.
- Kanoh, Shigeyoshi,Hongoh, Yukihiko,Katoh, Shingo,Motoi, Masatoshi,Suda, Hiroshi
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p. 405 - 406
(2007/10/02)
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- Synthesis and Chiral Recognition of Optically Active Crown Ethers incorporating a 4,4'-Biphenanthryl Moiety as the Chiral Centre
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Two chiral crown ethers (+)-S-(4) and (-)-(R,R)-(5) with a 4,4'-biphenanthryl moiety as the chiral centre have been prepared, and their chiral recognition properties were examined to show that (+)-(S)-(4) has a high enantiomer selectivity for 2-aminotetralin and 1,2-diphenylethylamine.
- Yamamoto, Koji,Noda, Koji,Okamoto, Yoshio
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p. 1065 - 1066
(2007/10/02)
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- The Asymmetric Ullmann Coupling Reaction of Chiral Diol Diesters of 1-Bromo-2-naphthoic Acid and 2-Halo-3-nitrobenzoic Acids: Highly Diastereoselective Synthesis of Atropisomeric 6,6'-Dinitrodiphenic Acids
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The copper-promoted Ullmann reaction of chiral diol diesters of 1-bromo-2-naphthoic acid induced axial dissymmetry into the newly formed 1,1'-binaphthyl bond: chiral diol, apparent net optical yield for the joining of two napphthyl units, and axial chirality induced are as follows: (S)-1,1'-binaphthyl-2,2'-diol, 71percent, S; (1S,2S)-1,2-diphenyl-1,2-ethanediol. 32percent, S; (1R,2R)-1,2-bis(ethoxycarbonyl)-1,2-ethanediol. 33percent.S; (4S,5S)-bis(hydroxymethyl)-2,2-dimethyl-1,3-dioxolane, 3.7percent, R.The reaction of (R)-1,1'-binaphthyl-2,2'-diol esters of 2-halo-3-nitrobenzoic acid gave up to 85percent net optical yield for the c oupling; the intramolecular cyclization proceeded with virtually complete diastereoselectivity to give cyclic diester of R,R-configuration in a 42percent isolated yield.This remarkable stereocontrol is ascribed to the steric requirement of the 12-membered cyclic diester structure containing rigid 1,1'-binaphthyl and 1,1'-biphenyl moiety.
- Miyano, Sotaro,Handa, Shigeru,Shimizu, Kunitoshi,Tagami, Katsuya,Hashimoto, Harukichi
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p. 1943 - 1947
(2007/10/02)
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- A Novel Clathrate Design: Selective Inclusion of Uncharged Molecules via the Binaphthyl Hinge and Appended Coordinating Groups. X-ray Crystal Structures and Binding Modes of 1,1'-Binaphthyl-2,2'-dicarboxylic Acid Host/Hydroxylic Guest Inclusions
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1,1'-Binaphthyl-2,2'-dicarboxylic acid (1) is demonstrated as a novel type of clathrate host whose main mode of action is derived from a combination of the steric barrier and the coordinative interaction principle which constitutes the new "coordinatoclathrate" strategy.Inclusion properties of the crystal lattice of 1 are revealed for a variety of uncharged organic guest molecules (30 examples), ranging from OH-, to NH-, to CH-acidic compounds such as alcohols, carboxylic acids, amides, and nitriles to rather unpolar compounds like bromobenzene and toluene.Marked discrimination selectivities in the clathrate formation from solvent mixtures are found in regard to the group functionality, the substitution pattern, and the molecular size of the guest species, making accessible a simple process for chemical compound separation.The stoichiometries and the increased-temperature as well as the reduced-pressure stabilities of the various clathrates are discussed.The principles of stucture of five different alcohol clathrates of 1 are determined with the aid of X-ray structure analysis at 273 K: 1*2MeOH (10) 1/n, a = 15.642 Angstroem, b = 14.532 Angstroem, c = 9.292 Angstroem, β = 95.14 deg, Z = 4>; 1*2EtOH (11) ; 1*2(2-PrOH) (13) ; 1*2-BuOH (15) 1/n, a = 12.009 Angstroem, b = 12.747 Angstroem, c = 14.982 Angstroem, β = 105.52 deg, Z = 4>; 1*ethylene glycol (24) 1/n, a = 14.276 Angstroem, b = 9.533 Angstroem, c = 15.556 Angstroem, β = 109.19 deg, Z = 4>.In all these cases, however, hydroxyl groups of the host molecules were found to be intercalated via large pseudo-ring formation between the carboxyl functions of at least two host units of opposite chirality with a different mode of hydrogen bridging.Depending on the host:guest stoichiometry (1:1 or 1:2) and on the nature of the guest molecules, these entities consist of three, four, or eight moieties (COOH, OH).The direction of the strong and cooperative bonds is always homodromic.The shape and the size of the cleft formed in the matrix of cooperating host moieties are shown to vary, matching the specific needs of coordinating interactions (hydrogen bonding) and topological requirements (branching, e.g.) of the guest species.
- Weber, Edwin,Csoregh, Ingeborg,Stensland, Brigitta,Czugler, Matyas
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p. 3297 - 3306
(2007/10/02)
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- Studies in Stereochemistry. 47. Asymmetric Induction by Leaving Group in Nucleophilic Aromatic Substitution
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We report here the first examples of transfer of asymmetry from a leaving group to a biaryl product in nucleophilic, aromatic substitution reactions.Chiral products 2--4,4-dimethyl-Δ2-oxazoline (6), 2--4,4-dimethyl-Δ2-oxazoline (8), and 2--4,4-dimethyl-Δ2-oxazoline (11) were produced in high to medium optical yields by aryl-aryl coupling reactions in which 1-naphthyllithium, 3-methoxy-2-naphthyllithium, or 2-methoxy-1-naphthylmagnesium bromide was treated with 2--4,4-dimethyl-Δ2-oxazolines 15-19.The alkoxy leaving groups of the naphthyloxazolines were derived from the naturally occuring alcohols l-menthol, quinine, quinidine, α-fenchol, and borneol.The oxazoline group activates the aromatic nucleus toward nucleophilic aromatic substitution by stabilizing the transition states leading to and from ?-complex intermediates.These reaction intermediates are diastereomeric and are therefore of unequal free energy.Thus one enantiomeric product is formed faster than the other.The configurations of starting materials and products (with the exception of 11) were established by converting them to compounds of established absolute configuration.The optical yields in the 14 reactions examined ranged from ca. >95percent to 8percent and the chemical yields from 88percent to 7percent.The l-menthoxy leaving group gave the highest chiral transfer efficiences (percent chemical yield x optical yield), which ranged from 65percent to 41percent.The more spherical, least dissymmetric α-fenchoxy and bornoxy groups gave the lowest optical yields (77-8percent ee) but rather good chemical yields (88-65percent).The quininoxy and quinidinoxy group produced the most consistently high optical yields (94-80percent ee) but the lowest chemical yields (7-27percent).These two leaving groups gave products of opposite configurations in the three systems examined.The highest value observed for the difference in free energy of the diastereomeric transition states was Δ(ΔG excit.)=2.4 kcal mol-1 and involved 2-methoxy-1-naphthylmagnesium bromide as nucleophile, quininoxy as leaving group, and 8 as product.Unlike most covalently bound chiral auxilliary units used for asymmetric induction in organic synthesis, those of the current study are displaced during the reaction.The direction of the configurational biases is interpreted in terms of the superposition of steric effects on the tendency of the lithium and magnesium ions to be ligated internally in the ?-complex intermediates.
- Wilson, Janet M.,Cram, Donald J.
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p. 4930 - 4943
(2007/10/02)
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- Asymmetric Synthesis of Axially Dissymmetric 1,1-Binaphthyls via an Intramolecular Ullmann Coupling Reaction of (R)- and (S)-2,2'-Bis(1-bromo-2-naphthylcarbonyloxy)-1,1'-binaphthyl
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An Ulmann reaction of the chiral bifunctional substrate containing two 1-bromo-2-naphthyl moieties, (S)-2,2'-bis(1-bromo-2-naphthylcarbonyloxy)-1,1'-binaphthyl, gives an intramolecularly coupled 12-membered cyclic diester in a 36 percent isolated yield.The intramolecular coupling reaction prodeeds with virtually complete diastereoselectivity to induce S-chirality into newly formed bond between the two naphthyl units.
- Miyano, Sotaro,Tobita, Masayuki,Hashimoto, Harukichi
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p. 3522 - 3526
(2007/10/02)
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- PARTIAL ASYMMETRIC SYNTHESIS OF ATROPISOMERIC 1,1'-BINAPHTHYLS VIA THE ULLMANN COUPLING REACTION OF CHIRAL ALCOHOL ESTERS OF 1-BROMO-2-NAPHTHOIC ACID
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The Ullmann coupling of 1-bromo-2-naphthoates of C-chiral alcohols of R- and S-configuration induced axial dissymmetry of R- and S-chirality, respctively, in the newly formed 1,1'-bond of the binaphthyls; the optical yield amounted up to 13percent where the chiral alcohol was l-menthol.
- Miyano, Sotaro,Tobita, Masayuki,Suzuki, Shoji,Nishikawa, Yukio,Hashimoto, Harukichi
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p. 1027 - 1030
(2007/10/02)
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