- Conformational effect on macroscopic chirality modification of cholesteric mesophases by photochromic azobenzene dopants
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Azobenzenes having different positional substituents were dissolved in cholesteric liquid crystals to make cholesteric pitches tunable by photoisomerization. E-to-Z photoisomerization of 3,3′-disubstituted or 2,2′-dimethyl-3,3′-disubstituted azobenzenes resulted in a moderate change or even no change in the maximum wavelengths of reflectivity of the cholesteric phase, whereas azobenzene or 4,4′-disubstituted azobenzenes showed much bigger changes. The different in the conformations between the E- and Z-isomers of the azobenzenes is discussed to explain the observed characteristics. The photoinduced modification of helical pitches by photoisomerization of achiral azobenzenes was identical between a pair of enantiomeric cholesteric solvents, suggesting no preferred intrinsic handedness of the achiral azobenzenes. Experimental results with the corresponding chiral azobenzene suggested that the contribution of the conformation of the azobenzene to the effective helical twisting power is more pronounced than that of the molecular chirality arising from the asymmetric carbon at the terminal alkyl substituents. The photoinduced shortening or lengthening of the helical pitch seems to be determined crucially by the thermal characteristics of the cholesteric liquid crystals.
- Ruslim, Christian,Ichimura, Kunihiro
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Read Online
- Effect of regioregularity and role of heteroatom on the chiral behavior of oligo(heteroalkyl thiophene)s
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Novel optically active oligothiophenes bearing electron-donating chiral side chains have been prepared by synthetic methods suitable to achieve regioregular head-to-tail and head-to-head/tail-to-tail derivatives. In particular, the chiral (S)-(2-methyl)butyl moiety was linked at position 3 of the thiophene ring through heteroatoms, such as S or O, to evaluate its effect on the macro molecular aggregation and, consequently, on the chiroptical properties of the material in the solid state. The materials have been fully characterized and investigated by optical and chiroptical methods upon aggregation both from the solution and as cast films. Compared with the related head-to-tail and head-to-head/tail-to-tail poly(3-alkyl)thiophene derivatives, with the same optically active moiety directly linked to the ring and possessing a higher polymerization degree, the chiroptical properties of the newly synthesized oligomers were significant, or even better, and provided insight into the role of intrachain–interchain interactions between the heteroatom and the thienyl sulfur atom.
- Marinelli, Martina,Angiolini, Luigi,Lanzi, Massimiliano,Di Maria, Francesca,Salatelli, Elisabetta
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Read Online
- Absolute configuration at the tricarballylic acid moieties of fumonisin B2
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The configuration at the chiral centers of the two tricarallylic acid moieties of fumonisin B2 is shown to be R. This stereochemistry is opposite to that recently suggested by others for the tricarballylic acid portions of fumonisin B1 and AAL toxin T(A).
- Boyle, Craig D.,Kishi, Yoshito
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Read Online
- Synthesis of a novel chiral DA-TD covalent organic framework for open-tubular capillary electrochromatography enantioseparation
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Herein, a novel chiral covalent organic framework, DA-TD COF, with good chemical/thermal stability was synthesized and used as a chiral stationary phase for open-tubular capillary electrochromatography enantioseparation. The DA-TD COF coated capillary exh
- Chen, Hongli,Chen, Xingguo,Lv, Wenjuan,Pan, Congjie,Wang, Guoxiu
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supporting information
p. 403 - 406
(2022/01/19)
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- Structure-Elucidating Total Synthesis of the (Polyenoyl)tetramic Acid Militarinone C §
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The (polyenoyl)tetramic acid militarinone C (1) heads a family of seven members. Before our work, the configuration of C-5 was unknown whereas the configurations of C-8′ and C-10′ were either (R,R) or (S,S). We synthesized the four stereoisomers of constitution 1, which conform with these insights. This included cross-coupling both enantiomers of the western building block (8) with both enantiomers of the eastern building block (9). The specific rotations of the resulting 1 isomers suggested that natural 1 is configured like the coupling partners (S)-8 and (R,R)-9. This conclusion was corroborated by degrading natural 1 to alcohol 35 and by proving its configurational identity with synthetic (R,R)-35.
- Brückner, Reinhard,Drescher, Christian,Hamburger, Matthias,Keller, Morris,Potterat, Olivier
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supporting information
(2020/03/30)
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- Magnetic substance and magnetic substance manufacturing method
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[object] A magnetization technique that enhances magnetic properties of an organic compound is provided without damaging properties of the organic compound or while maintaining the structure of the organic compound. [solution] The present disclosure is a method for manufacturing a magnetic substance composed of crystals of a magnetization target compound and an electron acceptor by combining the magnetization target compound with the electron acceptor; forming a solution by dissolving a mixture of the magnetization target compound and the electron acceptor in a solvent; maintaining the solution in a very low temperature state and allowing the solution to deposit the crystals of the magnetic target compound and the electron acceptor; and separating the crystals from the solvent.
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Page/Page column 12; 13
(2017/11/01)
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- Studies on tridecaptin B1, a lipopeptide with activity against multidrug resistant Gram-negative bacteria
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Previously other groups had reported that Paenibacillus polymyxa NRRL B-30507 produces SRCAM 37, a type IIA bacteriocin with antimicrobial activity against Campylobacter jejuni. Genome sequencing and isolation of antimicrobial compounds from this P. polymyxa strain show that the antimicrobial activity is due to polymyxins and tridecaptin B1. The complete structural assignment, synthesis, and antimicrobial profile of tridecaptin B1 is reported, as well as the putative gene cluster responsible for its biosynthesis. This peptide displays strong activity against multidrug resistant Gram-negative bacteria, a finding that is timely to the current problem of antibiotic resistance.
- Cochrane, Stephen A.,Lohans, Christopher T.,Van Belkum, Marco J.,Bels, Manon A.,Vederas, John C.
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p. 6073 - 6081
(2015/06/08)
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- Efficient Syntheses of Star-Branched, Multifunctional Mesogens
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Star-branched molecular architectures lend themselves to convergent synthesis strategies for creating materials that combine three or more functional modalities, but these approaches require a core moiety with several reactive groups that are orthogonal t
- Song, Shuang,Rudick, Jonathan G.
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supporting information
p. 3244 - 3247
(2015/07/15)
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- Molecular tectonics: Homochiral 3D cuboid coordination networks based on enantiomerically pure organic tectons and ZnSiF6
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Upon combining enantiomerically pure bis-monodentate organic tectons with ZnSiF6, homochiral 3D cuboid architectures displaying chiral channels are formed.
- Larpent, Patrick,Jouaiti, Abdelaziz,Kyritsakas, Nathalie,Hosseini, Mir Wais
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supporting information
p. 4468 - 4470
(2013/06/04)
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- Pheromone synthesis. Part 243: Synthesis and biological evaluation of (3R,13R,1′S)-1′-ethyl-2′-methylpropyl 3,13-dimethylpentadecanoate, the major component of the sex pheromone of Paulownia bagworm, Clania variegata, and its stereoisomers
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All of the four stereoisomers of (1′S)-1′-ethyl-2′-methylpropyl 3,13-dimethylpentadecanoate, the major component of the female sex pheromone of Clania variegata, were synthesized by employing olefin cross metathesis as the key reaction and starting from (R)- or (S)-2-methyl-1-butanol, (R)- or (S)-citronellal, and (S)-2-methyl-3-pentanol. Their bioassay revealed the (3R,13R,1′S)-isomer as the bioactive one, whose more efficient synthesis was achieved in two different ways by employing Wittig reaction as the key step.
- Mori, Kenji,Tashiro, Takuya,Zhao, Boguang,Suckling, David M.,El-Sayed, Ashraf M.
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experimental part
p. 2642 - 2653
(2010/05/18)
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- Pheromone synthesis. Part 240: Cross-metathesis with Grubbs I (but not Grubbs II) catalyst for the synthesis of (R)-trogodermal (14-methyl-8-hexadecenal) to study the optical rotatory powers of compounds with a terminal sec-butyl group
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(R)-Trogodermal (14-methyl-8-hexadecenal), the sex pheromone of Trogoderma species of pest insects against stored products, and its (S)-isomer were synthesized by using olefin cross-metathesis between (R)- or (S)-7-methyl-1-nonene and 8-nonenyl acetate as the key step. This step was successful with Grubbs I but not with Grubbs II catalyst. The latter caused randomization of the carbon skeleton to give a mixture of abnormal products with both longer or shorter carbon chains than the desired product. The specific rotations of 18 newly and 6 previously synthesized compounds with a terminal sec-butyl group were measured to conclude them to be [α]D +3.5 to +6.5 or -3.6 to -6.4.
- Mori, Kenji
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experimental part
p. 3900 - 3909
(2009/09/08)
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- Synthesis of all the four stereoisomers of (1′S)-1-ethyl-2-methylpropyl 3,13-dimethylpentadecanoate, the major component of the sex pheromone of Paulownia bagworm, Clania variegata
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All the four stereoisomers of (1′S)-1-ethyl-2-methylpropyl 3,13-dimethylpentadecanoate, the major component of the sex pheromone of Clania variegata, were synthesized by starting from (R)- or (S)-2-methylbutan-1-ol, (R)- or (S)-citronellal, and (S)-2-methylpentan-3-ol. Olefin cross metathesis was employed as the key reaction.
- Mori, Kenji,Tashiro, Takuya
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scheme or table
p. 3266 - 3269
(2009/09/05)
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- Effect of fluorocarbon chains on the mesomorphic properties of chiral imines and their complexes with copper(II)
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The synthesis and mesomorphism of new chiral imine compounds incorporating a fluorocarbon chain which have calamitic molecular shape and their complexes with copper(II) are reported. The liquid crystalline properties were investigated using polarised optical microscopy, differential scanning calorimetry and X-ray diffraction. Imine compounds with a semifluorinated chain and a short chiral chain show chiral smectic mesophases with dramatically enhanced mesophase stabilities compared to the related hydrocarbon derivatives. In addition, the first examples of mesogenic chiral salicylaldiminate copper(II) complexes carrying semifluorinated alkyl chains at their peripheries have been synthesized and their liquid crystalline properties were investigated.
- Ocak, Hale,Bilgin-Eran, Belkiz,Tschierske, Carsten,Baumeister, Ute,Pelzl, Gerhard
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scheme or table
p. 6995 - 7001
(2010/05/18)
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- Chiral ethylhexyl substituents for optically active aggregates of π-conjugated polymers
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We report an efficient synthesis of chiral (2S)-ethylhexanol for functionalizing and solubilizing conjugated polymers. The α-substituted chiral ethylhexyl side chains were obtained through a powerful and flexible asymmetric synthesis using pseudoephedrine as a chiral auxiliary. The dependence of the properties of conjugated polymers on molecular structure is investigated by circular dichroism, fluorescence, and absorption spectroscopy on two new chiral conjugated polymers, poly(3,3-bis((S)-2-ethylhexyl)-3,4-dihydro-2H- thieno[3,4-b][1,4]dioxepine) (PProDOT((2S)-ethylhexyl)2) and poly(3,3-bis((S)-2-methylbutyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine) (PProDOT((2S)-methylbutyl)2). The properties of PProDOT((2S)- ethylhexyl)2) differ significantly from those of its methylbutyl analog as investigated by chiral aggregation providing insight into the role of interchain interactions in these subsecond switching electrochromic polymers.
- Grenier, Christophe R. G.,George, Subi J.,Joncheray, Thomas J.,Meijer,Reynolds, John R.
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p. 10694 - 10699
(2008/03/13)
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- Field-induced ferrimagnetic state in a molecule-based magnet consisting of a CoII ion and a chiral triplet bis(nitroxide) radical
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We present the synthesis, crystal structure, and temperature and field dependence of the magnetic properties of a new molecule-based magnet, [Co(hfac)2]7bull;BNO* (1), where hfac = 1,1,1,5,5,5- hexafluoroacetylacetonato and BNO* is the chiral t
- Numata, Youhei,Inoue, Katsuya,Baranov, Nikolai,Kurmoo, Mohamedally,Kikuchi, Koichi
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p. 9902 - 9909
(2008/03/11)
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- CHIRAL ALKOXY ALCOHOLS, CHIRAL 1 ,3-PHENYLENE-BΙS[4-(4-ALKOXY) PHENYLIMINOMETHYL] BENZOATES AND PROCESSES FOR PREPARATION THEREOF
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The present invention relates to chiral alkoxy alcohols, chiral 1 ,3- phenylene bιs[4-(4-alkoxy)phenylιmιnomethyl]benzoates, and the preparation methods of them In particular, the chiral alkoxy alcohol of the present invention can be used for synthesizing
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Page/Page column 18; 19
(2010/10/20)
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- Odd-even behavior of ferroelectricity and antiferroelectricity in two homologous series of bent-core mesogens
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Two chiral bent-core mesogens Pn-O-PIMB(n- 2)* (n= 9 and 10) and their oxygen analogues Pn-O-PIMB(n - 2)*-(n - 4)O (n = 8, 9, and 10) with ω-[(S)-amyloxy]alkoxy terminal groups were prepared, and their phase structures were investigated by means of electr
- Lee, Seng Kue,Heo, Sung,Lee, Jong Gun,Kang, Kyung-Tae,Kumazawa, Kazuya,Nishida, Koushi,Shimbo, Yoshio,Takanishi, Yoichi,Watanabe, Junji,Doi, Takayuki,Takahashi, Takashi,Takezoe, Hideo
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p. 11085 - 11091
(2007/10/03)
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- Synthesis and odor evaluation of stereoisomers of imine derivatives in roasted spotted shrimp
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All possible stereoisomers of imine derivatives 1-4. which have the characteristic roast odor of seafood, were synthesized. As a result of odor evaluation of all isomers, we found that each isomer has a different and characteristic odor of roasted seafood.
- Tachihara, Toru,Ishizaki, Susumu,Kurohayashi, Yoshiko,Tamura, Hiroshi,Ikemoto, Youichi,Onuma, Atsushi,Yoshikawa, Keisuke,Yanai, Tetsuya,Kitahara, Takeshi
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p. 274 - 279
(2007/10/03)
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- Process of preparing discotic liquid crystalline compounds
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The invention relates to a process of preparing a discotic liquid crystalline compound by intramolecular oxidative cyclisation of a diaryl compound in an organic solvent in the presence of a strong acid, characterized in that an oxidative agent comprising a chrom(VI)oxide derivative is used, to discotic liquid crystalline compounds obtainable from said process, to liquid crystalline media, (co)polymers or polymer networks with columnar phases comprising said discotic liquid crystalline compounds, and to the use of said discotic liquid crystalline compounds, liquid crystalline media or liquid crystalline (co)polymers with columnar phases for liquid crystal displays, optical elements like polarizers, compensators or colour filters, chemical sensors, charge transport materials, optical storage media, nonlinear optics, decorative pigments, adhesive or synthetic resins with anisotropic mechanical properties.
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- Synthesis of asymmetric dibenzophosphole 5-oxides: The first dibenzophosphole-based family of compounds with liquid crystalline behaviour
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A synthesis of a new family of chiral dibenzophosphole 5-oxides is described. Using high-yield known reactions we report a method for the synthesis and optical resolution of chiral dibenzophospholes from an unsubstituted system. These molecules are the first examples of a new asymmetrically substituted dibenzophosphole-based group of systems with liquid crystal properties.
- Dura?n, Ernesto,Velasco, Dolores,Lo?pez-Calahorra, Francisco
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p. 825 - 855
(2007/10/03)
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- Stereoisomeric indole compounds, process for the preparation of the same, and use thereof
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Novel stereoisomeric indole compounds of the formula (1), a process for the preparation the same, and use thereof wherein, Y represents the group wherein, X represents alkyl group having 1-5 carbon atom(s) (the alkyl group may be substituted with hydroxyl group, carboxyl group, amino group, methylthio group, mercapto group, guanidyl group, imidazolyl group or benzyl group), and R1and R2represent each independently hydrogen atom, alkyl group, aralkyl group, cycloalkyl group or aryl group;R represents hydrogen atom, alkyl group, aralkyl group, cycloalkyl group, aryl group, monovalent metal, amine or ammonium; and the symbol ‘*’ represents a position of an asymmetric carbon atom. The above-mentioned compounds can be prepared by condensing tryptophan with a stereoisomeric α-amino acid or carboxylic acid to form an amide form and subjecting or carboxylic acid to form an amide form and subjecting the amide form to oxidative cyclization to form an oxazole ring at once. The compounds exhibit; physiological activities such as inhibitory action against lipid peroxidation, and can be therefore utilized in the form of lipid peroxidation inhibitors containing the same as the active ingredient.
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Page column 9-10
(2010/11/30)
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- A practical synthesis of the lipophilic side chain of the polyoxypeptins
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The lipophilic side chain of the cyclic depsipeptide polyoxypeptin A (1) and B (2), strong apoptosis inducers, has been synthesised as an ester of mixed methyl ketal 18. The key step is an asymmetric anti-aldol reaction of the designed 2-(N-2-methylbenzyl
- Lorca, Miguel,Kurosu, Michio
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p. 2431 - 2434
(2007/10/03)
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- Synthesis and structure of poly(phenyl isocyanate)s bearing an optically active alkoxyl group
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Novel optically active phenyl isocyanate derivatives (1-6) bearing an (R)-sec-butoxy, (S)-2-methylbutoxy or (S)-3,7-dimethyloctyloxy group at the meta or para position on the phenyl ring were prepared and polymerized with an anionic initiator in tetrahydrofuran (THF). The resulting polymers from 1, 2, 4 and 6 showed much greater specific rotation than that of the corresponding monomers and an intense circular dichroism (CD) band in the main-chain absorption region, indicating that these polymers have a predominantly one-handed helical conformation in solution. On the other hand, the polymers obtained from 3 and 5 showed a much smaller specific rotation than that of the above polymers at room temperature. The polymers from 2 and 5 showed a remarkable change in optical activity with change in temperature, and the specific rotation of the polymers changed from a positive to a negative value with decrease in temperature. The CD band of the polymers in the absorption region due to the main chain changed from a positive to a negative peak with a change in specific rotation. These results indicate that poly-2 and poly-5 undergo a thermally induced helix-helix transition in THF. The temperature for the helix-helix transition of poly-2 was independent of the degree of polymerization. Poly-2 exhibited a reversible helix-helix transition in chloroform and diethyl ether and also in THF, whereas in toluene and dichloromethane such a transition was not observed. Copyright
- Hino, Kyoko,Maeda, Katsuhiro,Okamoto, Yoshio
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p. 361 - 367
(2007/10/03)
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- Carboxylate compounds, liquid crystal materials liquid crystal compositions and liquid crystal elements
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There is provided a carboxylic acid compound represented by the following formulae (I) to (IV): STR1 a liquid crystal material consisting of the carboxylic acid ester compound, a liquid crystal composition comprising the carboxylic acid ester compound, and a liquid crystal element using the carboxylic acid ester compound. There can be obtained advantages such as low operating temperature, high speed switching, very small electric power consumption, and high-stable contrast.
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- Scavenger assisted combinatorial process for preparing libraries of tertiary amine compounds
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This invention relates to a novel solution phase process for the preparation of tertiary amine combinatorial libraries. These libraries have utility for drug discovery and are used to form wellplate components of novel assay kits.
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- Pheromone Synthesis, CLXXVI: Synthesis of the four stereoisomers of 3,13-dimethylheptadecane, the major sex pheromone component of the western false hemlock looper
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All of the four stereoisomers of 3,13-dimethylheptadecane (1), the female-produced sex pheromone of the western false hemlock looper (Nepytia freemani), were synthesized by starting from the enantiomers of citronellol (2a) and 2-methyl-1-butanol (4a). VCH Verlagsgesellschaft mbH, 1996.
- Takikawa, Hirosato,Shirai, Yasuo,Kobayashi, Makoto,Mori, Kenji
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p. 1965 - 1970
(2007/10/03)
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- Optical Isomers of 3,13-Dimethylheptadecane: Sex Pheromone Components of the Western False Hemlock Looper, Nepytia freemani (Lepidoptera: Geometridae)
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(3S,13R)-3,13-Dimethylheptadecane [(3S,13R)-3,13-dime-17Hy] is the major pheromone component of the western false hemlock looper (WFHL), Nepytia freemani. In comparative gas chromatographic-electroantennographic detection (GC-EAD) analyses of stereoselectively synthesized isomers, 1 pg of (3S,13R)-dime-17Hy elicited significantly stronger electrophysiological responses by male WFHL antennae than did 1 pg of separately injected (3R,13R)-, (3R,13S)- or (3S,13S)-3,13-dime-17Hy. In field experiments with individually tested stereoisomers, (3S,13R)-3,13-dime-17Hy was the only stereoisomer to attract males, but the four-stereoisomer blend was 3.6 times more attractive. Quaternary and all binary combinations of (3S,13R)-3,13-dime-17Hy with the other stereoisomers were equally attractive, suggesting that synergistic behavioral activity in WFHL resided with either one of (3R,13R)-, (3R,13S)-, or (3S,13S)-3,13-dime-17Hy. Because optical isomers of (di)methylhydrocarbons do not separate on currently available columns, it remains unknown whether female WFHL also produce a four-stereoisomer pheromone blend. Substitutionality of pheromone stereoisomers without loss of behavioural activity has not previously been reported, but favorably compares with the concept of pheromone redundancy that was first suggested for the multiple pheromone component blend of the cabbage looper moth, Trichoplusia ni.
- King, G. G. Skip,Gries, Regine,Gries, Gerhard,Slessor, K. N.
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p. 2027 - 2046
(2007/10/03)
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- Synthesis of both the enantiomers of aseanostatin P5 (sarcinic acid), an inhibitor of myeloperoxidase release, and four diastereomers of aggreceride A, a platelet aggregation inhibitor.
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Both the enantiomers of aseanostatin P5 (sarcinic acid), an inhibitor of myeloperoxidase (MPO) release from human polymorphonuclear leukocytes (PMN), with high optical purity were synthesized by starting from (S)-2-methylbutanol and methyl (S)-3-hydroxy-2
- Kitahara,Aono,Mori
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- Electronic Hyperpolarisabilities of Some Mesogenic Stilbazole Complexes of Rh(I) and Ir(I)
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The electronic hyperpolarisabilities of a chiral 4-alkoxystilbazole and its complexes with Rh(I) and Ir(I) are reported and discussed in terms of the acceptor properties of the metal fragment. - Keywords: Rhodium, iridium, stilbazole, nonlinear optics
- Bruce, Duncan W.,Thornton, Anna
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p. 253 - 256
(2007/10/02)
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- OZONOLYSIS OF ALKENES AND REACTIONS OF POLYFUNCTIONAL COMPOUNDS. XLVI. SYNTHESIS OF (4S,8S)-4,8-DIMETHYLDECANAL AND ITS DIMETHYL ACETAL
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From accessible chiral structural blocks, namely, (R)-methyl-citronellate and (S)-2-methyl-1-butanol, (6S,10S)-2,6,10-trimethyl-2-dodecene was synthesized.The ozonolysis of this gave (4S,8S)-4,8-dimethyldecanal, one of the stereoisomers of the aggregation pheromone of the meal worms Tribolium confusium and T. castaneum, and its dimethyl acetal.
- Odinokov, V. N.,Akhmetova, V. R.,Khasanov, Kh. D.,Abduvakhabov, A. A.,Sul'tanmuratova, V. R.,Tolsikov, G. A.
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p. 915 - 918
(2007/10/02)
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- Synthesis of the Three Stereoisomers of Auxin-Glutaric Acid to Confirm the Non-Existence of Koegl's Auxin-a and -b
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All of the three possible stereoisomers of (5S,1'S)-4-carboxy-5-methyl-1-(1'-methylpropyl)heptanoic acid were synthesized and their stereostructures assigned unambiguously by 13C-NMR and X-ray analyses.The melting points and the specific rotations of the
- Mori, Kenji,Kamada, Atsushi,Kido, Masaru
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p. 775 - 781
(2007/10/02)
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- Pheromone Synthesis, CXXV. Synthesis of the Four Possible Stereoisomers of 3,7-Dimethylnonadecane, the Female Sex Pheromone of Agromyza frontella Rondani
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The synthesis of the four possible stereoisomers of 3,7-dimethylnonadecane (1) has been achieved by starting from the enantiomers of methyl 3-hydroxy-2-methylpropanoate (2) and (R)-(+)-citronellic acid (3).
- Mori, Kenji,Wu, Jiang
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p. 213 - 217
(2007/10/02)
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- CD OF PRIMARY AMINES AND 1- OR 3-SUBSTITUTED TETRAHYDROISOQUINOLINES IN PRESENCE OF
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The syntheses of (S)-(-)-1,2-dimethyl-1,2,3,4-tetrahydroisoquinoline (IX) and S-(+)-2,3-dimethyl-1,2,3,4-tetrahydroisoquinoline (XVI) in optically pure form and with known absolute configuration is described.The CD and NMR spectra of these compounds and of most of their intermediates are given, and from these data could be deduced, that the N-methyl groups of the two bases IX and XVI adopt different conformations in solution, but the same (viz. axial) in their complexes with .
- Diener, Wolfgang,Frelek, Jadwiga,Snatzke, Guenther
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p. 954 - 965
(2007/10/02)
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- Liquid crystal compounds and optically active compounds
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A compound usefull for liquid crystal component which is represented by the following formulas (1), (2), (3), or (4) ;, R1 -X1 -A1 -( A2 )n-Y1 -A3 -X2 -R2 (1), R1 -X1 -( A3 -Y1 )N-A1 -A2 -X2 -R2 (2), R3 -X1 -A4 -Y1 -A3 -X2 -R4 (3), R3 -X1 -A5 -Y1 -A1 -A2 -X2 -R4 (4), wherein R1 ,R2 ,R3 and R4 are C1 18 alkyl groups; X1 and X2 is -, O, S, -C≡C- or divarent groups such as COO, OCO, CH2 O or OCH2
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- Photosynthetic Electron Transport Inhibition by Phlorophenone Derivatives
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The structure/activity relationships of phlorophenone derivatives including grandinol and homograndinol, which are potent inhibitors of photosynthetic electron transport (PET) in Eucalyptus grandis, were examined.The results indicate that at least one acy
- Yoneyama, Koichi,Asami, Tadao,Crow, Wilfrid D.,Takahashi, Nobutaka,Yoshida, Shigeo
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p. 471 - 476
(2007/10/02)
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- 48. Ferroelectric Liquid Crystals Part 2 Chiral Phenyl Benzoates Incorporating a trans-1,4-Disubstituted Cyclohexane Ring
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About forty novel phenyl benzoates also incorporating a trans-1,4-disubstituted cyclohexane ring and a chiral centre have been prepared.The dependence of the liquid-crystal transition temperatures of this new class of compounds on lateral substituents, diverse central linkages, chain lengths, and position of the chiral centre has been studied systematically.The synthesis and liquid-crystal transition temperatures of these new compounds are described in detail.
- Kelly, Stephen M.,Buchecker, Richard
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p. 451 - 460
(2007/10/02)
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- CHIRAL SMECTIC LIQUID CRYSTALLINE POLYMERS
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The synthesis of side-chain liquid crystalline polysiloxanes, copolysiloxanes and of tetracyclosiloxanes containing chiral mesogenic side groups, i.e., trans-2-5--1,3-dioxane, trans-2-p-(2(S)-
- Hahn, Bruce,Percec, Virgil
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p. 125 - 150
(2007/10/02)
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- Synthesis of the chiral components of the sex pheromone of Adoxophyes leaf roller moths
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The optically pure (R) and (S) enantiomers of 10-methyldodecyl acetate were synthesized from (R)-5-acetoxy-4-methylpentanoic acid and (S)-2-methylbutanol, respectively, using the condensation of (R)- and (S)-2-methylbutylmagnesium bromides with 8-tosyloxyoctyl acetate in the presence of Li2CuCl4 in the key step.
- Cheskis, B. A.,Moiseenkov, A. M.
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- SYNTHESIS AND THERMAL PROPERTIES OF SIDE CHAIN TYPE LIQUID CRYSTALLINE POLYMERS WITH CHIRAL UNIT IN THE FLEXIBLE MOIETY
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This paper is concerned with the synthesis and thermal properties for five families of side-chain type liquid crystalline polymers.All these side-chain type polymers showed an enantiotropic mesomorphic nature.A sharp reflexion was observed in the small angle region, whereas a broad halo or a relatively sharp peak was also detected in the wide angle region for all the polymers.The experimental values of the thickness of the smectic layer which can be easily assigned by the polarizing microscopic measurements were smaller than that of the calculated ones.This difference would be caused from the tilted arrangement in the smectic layer or smectic A like structure in which the side chain would be overlapped.
- Koide, Naoyuki,Uehara, Keiichi,Iimura, Kazuyoshi
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p. 151 - 162
(2007/10/02)
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- PREPARATION OF (S)-2-METHYLBUTYLAMINE AND SYNTHESIS OF CHIRAL ISOLEUCINE AND alloISOLEUCINE.
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A four-step synthesis (45 percent total yield) of a mixture of chiral pure L-isoleucine and D-alloisoleucine is reported, via a route comprising an anodic oxidation of suitable acylamide precursors.Efficient preparations for (S)-2-methylbutylamine from the cheap parent (S)-alcohol are described.
- Anteunis, M. J. O.,Callens, R.,Witte, M. De,Reyniers, M. F.,Spiessens, L.
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p. 545 - 554
(2007/10/02)
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- SYNTHESIS AND MESOMORPHYSM OF SOME NEW FERRO-ELECTRIC SMECTIC LIQUID CRYSTALS
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In this work, compounds having the general formula: (I) (II) with (X=H, Br, CN, Cl) and (R1 (or/and) R2=3-methyl-hexyl or 2-methyl-butyl, n-alkyl were prepared and their phase transition temperatures and mesomorphic properties determin
- Decobert, Guy,Dubois, Jean-Claude
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p. 237 - 248
(2007/10/02)
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- Diastereoselective Synthesis of Nitroaldol Derivatives
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Three methods are described by which diastereomerically enriched nitroaldols and their O-silylated derivatives can be prepared. threo-Nitroaldols prevail up to 10:1 over the erythro-isomers if doubly deprotonated nitroaldols 28 are quenched with acetic acid (THF/HMPT or DMPU, -100 deg C) (see Scheme 5 and Table 2).O-Trimethyl- or O-(t-butyl)dimethylsilylated (TBDMSi) erythro-nitroaldols can be obtained by protonation of the corresponding lithium nitronates (35, 39) in THF at low temperature (see Schemes 6 and 7).The erythro-O-TBDMSi-nitroaldol derivatives are also formed in the fluoride catalyzed addition of TBDMSi-nitronates (40-45) to aldehydes (see Schemes 8 and 9).In the latter reaction no 1,2-asymmetric induction is observed if α-branched silylnitronates or aldehydes are employed (see 48/49 and 50/51). - The stereochemical course of the reactions leading to erythro-O-TBDMSi-nitroaldols follows topological rules of broad applicability (see Scheme 10); possible mechanisms are discussed.- The configuration of erythro/threo-nitroaldols is determined by chemical correlation (see 24-26) and by 13C-NMR. spectroscopy. - Some examples of the preparation of diastereomerically enriched 1,2-aminoalcohols by reduction of the corresponding nitro compounds without loss of configurational purity are described (see Schemes 11 and 12).
- Seebach, Dieter,Beck, Albert K.,Mukhopadhyay, Triptikumar,Thomas, Elizabeth
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p. 1101 - 1133
(2007/10/02)
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