- New variants of polymorphism in banana-shaped mesogens with cyano-substituted central core
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A new series of achiral five-ring banana-shaped compounds is presented which exhibit a cyano substituent in the 4-position of the central core. It follows from X-ray investigations and from NMR, microscopical and electro-optical measurements that all members of the series do not only form the chiral B2 phase characteristic of a bent molecular shape, but also SmA and SmC (in one case also nematic) phases. The electro-optical studies on the B2 phase prove an antiferroelectric ground state which can be switched into ferroelectric states. On the base of the experimental data plausible structure models have been proposed.
- Wirth,Diele,Eremin,Pelzl,Grande,Kovalenko,Pancenko,Weissflog
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Read Online
- Lewis acid-promoted site-selective cyanation of phenols
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An efficient Lewis acid-promoted site-selective electrophilic cyanation of 3-substituted and 3,4-disubstituted phenols has been developed. The cyanation reactions using MeSCN as the cyanating reagent proceeded efficiently to afford a wide range of 2-hydroxybenzonitriles with high efficiency and excellent regioselectivity. This protocol could provide a practical method for the synthesis and modification of biologically active molecules.
- Yang, Wen,Zhang, Wu,Zhao, Wanxiang
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supporting information
p. 4604 - 4609
(2020/07/04)
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- Metal-Free Regioselective Monocyanation of Hydroxy-, Alkoxy-, and Benzyloxyarenes by Potassium Thiocyanate and Silica Sulfuric Acid as a Cyanating Agent
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A novel and efficient metal- and solvent-free regioselective para-C-H cyanation of hydroxy-, alkoxy-, and benzyloxyarene derivatives has been introduced, using nontoxic potassium thiocyanate as a cyanating reagent in the presence of silica sulfuric acid (SSA). The desired products are obtained in good to high yields without any toxic byproducts.
- Sardarian, Ali Reza,Dindarloo Inaloo, Iman,Modarresi-Alam, Ali Reza,Kleinpeter, Erich,Schilde, Uwe
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p. 1748 - 1756
(2019/02/05)
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- Development of Polar Order by Liquid-Crystal Self-Assembly of Weakly Bent Molecules
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Organic ferroelectrics are of growing importance for multifunctional materials. Here we provide an understanding of the distinct stages of the development of sterically induced polar order in liquid-crystalline (LC) soft matter. Three series of weakly bent molecules derived from 4-cyanoresorcinol as the bent core unit with laterally fluorinated azobenzene wings have been synthesized, and the effects of the position of fluorine substitution, alkyl-chain length, and temperature on the LC self-assembly and polar order were studied. In the LC phases a paraelectric–ferroelectric transition took place as the size of the polar domains gradually increased, thereby crossing a permittivity maximum, similar to inorganic solid-state ferroelectrics. An increase in polar coherence length simultaneously led to a transition from synpolar to antipolar domain correlation in the high-permittivity paraelectric range. Associated with the emergence of polar order was the development of a tilted organization of the molecules and a growing coherence of tilt. This led to a transition from non-tilted via tilt-randomized uniaxial to long-range-tilted biaxial smectic phases, and to surface-stabilized symmetry breaking with the formation of chiral conglomerates and field-induced tilt. Moreover, there is a remarkably strong effect of the position of fluorination; polar order is favored by peripheral core substitution and is suppressed by inside-directed fluorination.
- Alaasar, Mohamed,Prehm, Marko,Poppe, Silvio,Tschierske, Carsten
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p. 5541 - 5556
(2017/04/27)
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- Perfluoroalkanosulfonyl fluoride: A useful reagent for dehydration of aldoximes to nitriles
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The reaction of a variety of aldoximes with perfluoroalkanosulfonyl fluoride in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in dichloromethane smoothly generated the corresponding nitriles in 70%-95% yields.
- Yan, Zhao-Hua,Tian, Huan,Zhao, Dong-Dong,Jin, Hong-Ai,Tian, Wei-Sheng
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- Discovery of phenoxybutanoic acid derivatives as potent endothelin antagonists with antihypertensive activity
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A series of phenoxybutanoic acid derivatives were synthesized and tested for their antagonistic activity on the contraction of the rat thoracic aortic ring induced by endothelin-1. Preliminary screening results showed that 6e and 6g with benzoheterocycles demonstrated significant antagonistic activities when compared to the reference compound BQ123. The results from additional assays for the binding affinity and selectivity for endothelin receptors showed that 6e was a selective ETA antagonist with a nanomolar IC50. Moreover, 6e was effective in relieving hypoxia-induced pulmonary arterial hypertension and right ventricular weight ratio. Therefore, 6e may have potential for further development as a therapeutic agent for the treatment of cardiovascular diseases.
- Cai, Jin,Liu, Ligang,Hong, Kwon Ho,Wang, Peng,Li, Lushen,Cao, Meng,Sun, Chunlong,Wu, Xiaoqing,Zong, Xi,Chen, Junqing,Ji, Min
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p. 657 - 667
(2015/02/19)
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- NOVEL COMPOUND HAVING SKIN-WHITENING, ANTI-OXIDIZING AND PPAR ACTIVITIES AND MEDICAL USE THEREFOR
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Provided are a novel compound having skin-whitening, anti-oxidizing and PPAR activities and a medical use thereof, and the compound has skin-whitening activities for the suppression of tyrosinase, and accordingly, is useful for use in skin-whitening pharmaceutical composition or cosmetic products; has anti-oxidant activities, and accordingly, is useful for the prevention and treatment of skin-aging; and has PPAR activities, and in particular, PPARα and PPARγ activities, and accordingly, is useful for use in pharmaceutical compositions or health foods which are effective for the prevention and treatment of obesity, metabolic disease, or cardiovascular disease.
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Paragraph 0293-0295
(2014/02/16)
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- 4-cyanoresorcinol-based bent-core mesogens with azobenzene wings: Emergence of sterically stabilized polar order in liquid crystalline phases
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A new series of azobenzene containing bent-core molecules incorporating 4-cyanoresorcinol as the central core unit exhibiting cybotactic nematic, rectangular, columnar, and different types of tilted smectic (SmC) phases are synthesized. The mesophase behavior and phase structures are characterized in bulk and freely suspended films using a variety of experimental techniques. Depending on the chain length and temperature a series of different mesophases is observed in these compounds, ranging from cybotactic nematic via paraelectric SmC phases, polarization randomized SmCsPR phases to ferroelectric and antiferroelectric SmC phases, associated with increasing size and correlation length of the polar domains. Spontaneous formation of chiral domains is observed in the paraelectric SmC and the SmCsPR phases and discussed in relation with superstructural chirality, bend elastic constants, and surface effects. Development of polar order in tilted smectic liquid crystalline phases (SmC) of bent-core mesogens is found to take place with increasing polar domain size in a series of distinct phases via a paraelectric and a new randomized polar SmC phase (SmCsPR) to a ferroelectric phase, which then becomes modulated and finally changes to an antiferroelectric phase.
- Alaasar, Mohammed,Prehm, Marko,May, Kathrin,Eremin, Alexey,Tschierske, Carsten
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p. 1703 - 1717
(2014/04/03)
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- Heterogeneous catalytic method for the conversion of aldoximes into nitriles using molecular sieve modified with Copper(II)
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A simple heterogeneous metal-catalyzed method was developed for the transformation of aldoximes into nitriles. Molecular sieve (4 A) modified with copper(II) proved to be an efficient catalyst for the conversion. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file.
- Kiss, Arpad,Hell, Zoltan
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supporting information
p. 1778 - 1786
(2013/05/22)
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- Effects of chain branching and chirality on liquid crystalline phases of bent-core molecules: Blue phases, de Vries transitions and switching of diastereomeric states
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Bent-core molecules based on a resorcinol bisbenzoate core with a series of distinct substituents in different positions at the central resorcinol core have been synthesized and characterized. The focus is on the effect of branched terminal groups in the racemic and chiral forms on the mesomorphic properties. These were investigated by differential scanning calorimetry, optical polarizing microscopy, X-ray diffraction, electro-optic and dielectric methods. Only bent-core mesogens derived from 4-cyanoresorcinol exhibit liquid crystalline phases and the mesophases of these compounds are strongly influenced by the branching and enantiomeric composition of the terminal chains. Depending on the structure of the rod-like wings and the enantiomeric composition, cybotactic nematic phases (NcybC), BPIII-like isotropic mesophases (BPIII cybC*) and various polar and apolar smectic phases (SmA, SmC, SmC*, SmCsPA, SmCsPA*) are formed. For one compound, a de Vries type smectic phase is observed and it appears that with decreasing temperature, order develops in two steps. First, at the SmA to SmC transition, the tilt direction becomes long range ordered and in a second step a long range ordering in bend direction takes place. Hence, for the optically active compound a transition from chirality induced polar switching to bend induced (shape induced) antiferroelectricity takes place. In this SmCsPA* phase a homogeneous layer chirality is induced under an applied electric field which interacts with the fixed molecular chirality leading to the energetically favoured diastereomeric state and giving rise to a field direction dependent uniform tilt director orientation. Field reversal induces a flipping of the layer chirality, which first leads to the less favorable diastereomeric state, and then this slowly relaxes to the more stable one by a spontaneous reversal of the tilt direction.
- Ocak, Hale,Bilgin-Eran, Belkiz,Prehm, Marko,Schymura, Stefan,Lagerwall, Jan P. F.,Tschierske, Carsten
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scheme or table
p. 8266 - 8280
(2012/03/10)
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- Nematic phases of bent-core mesogens
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Bent-core mesogens derived from 4-cyanoresorcinol with terminal alkyl chains have been synthesized and investigated by polarizing microscopy, XRD and electro-optical methods. Short chain compounds have exclusively nematic phases which can be cooled to ambient temperature. These nematic phases are similar to ordinary nematic phases with only nearest neighbour correlation (N) whereas long chain compounds form SmC-type cybotactic clusters and these cybotactic nematic phases (NcybC) can be regarded as strongly fragmented SmC phases. The chain length dependent as well as temperature dependent structural transition from N to NcybC is continuous and associated with a change of the position and intensity of the small angle scattering in the XRD patterns. Moreover, a temperature dependent stepwise transition from cybotactic nematic phases to different types of non-polar and tilted smectic phases (SmC (I) and SmC(II)) is observed with a mesophase composed of elongated, but not yet fused cybotactic clusters (CybC) as an intermediate state of this transition. This improves the understanding of the nature and special properties of the nematic phases formed by bent-core molecules as well as their transition to smectic phases and it paves the way to new materials with spontaneous or field-induced biaxial nematic phases at ambient temperatures.
- Keith, Christina,Lehmann, Anne,Baumeister, Ute,Prehm, Marko,Tschierske, Carsten
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scheme or table
p. 1704 - 1721
(2011/10/19)
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- Development of polar order in liquid crystalline phases of a banana compound with a unique sequence of three orthogonal phases
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Alkyl substituted 4-cyanoresorcinol 1,3-bisbenzoates with terephthalate based rod-like wings show a series of three orthogonal smectic phases SmA-SmAPR-SmAPA.
- Keith, Christina,Prehm, Marko,Panarin, Yuri. P.,Vij, Jagdish K.,Tschierske, Carsten
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supporting information; scheme or table
p. 3702 - 3704
(2010/08/07)
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- Synthesis of benzonitriles from substituted benzaldehyde
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There is a significant demand for organic nitriles, based on their versatility in reactions. Compounds prepared from nitriles have properties including superoxide inhibition, ferrielectric liquid crystal dopant, antipicornaviral agents, anti-inflammatory agents, anti-asthma agents, and fibringoen antagonists. The present invention discloses a facile synthesis for 2,4-dihydroxybenzonitrile, and ethers and diethers thereof, from 2,4-dihydroxybenzaldehyde or 2,4-dimethoxybenzaldehyde. The present invention also discloses a method of preparing a class of iron chelating agents related to desferrithiocin, all of which contain a thiazoline ring. In this method, 2,4-dihydroxybenzonitrile is condensed with (S)-2-methylcysteine.
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Page/Page column 3
(2008/06/13)
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- A simple and highly efficient one-pot chemoselective synthesis of nitriles from aldehydes: Mechanistic insight and selectivity control through modulation of electronic and steric factors
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Aldehydes are converted into nitriles in a one-pot reaction by treatment with H2NOH·HCl in dipolar aprotic solvents under heating. Amongst various solvents NMP offers the best results. No competitive ether cleavage (e.g. methoxy, benzyloxy) or aromatic nucleophilic substitution (e.g. nitro or chloro) takes place for substrates beating such functionalities. Electronic and steric factors around the aldehyde carbon affect the rate of nitrile formation. Excellent to moderate selectivity is observed during intermolecular competition between pair of aldehydes with varying electronic and steric requirements.
- Chakraborti,Kaur,Roy
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p. 1000 - 1006
(2007/10/03)
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- One-pot synthesis of nitriles from aldehydes under microwave irradiation: Influence of the medium and mode of microwave irradiation on product formation
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Chemoselective transformation of aldehyde to nitrile takes place in a one-pot reaction by treatment with H2NOHHCl in N- methyl-2-pyrrolidinone (NMP) under microwave irradiation using convection mode.
- Chakraborti, Asit K.,Kaur, Gurmeet
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p. 13265 - 13268
(2007/10/03)
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- Desazadesmethyldesferrithiocin analogues as orally effective iron chelators
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Further structure-activity studies of desferrithiocin analogues are carried out. (S)-Desazadesmethyldesferrithiocin, 2-(2-hydroxyphenyl)-Δ2- thiazoline-4(S)-carboxylic acid, serves as the principal framework in the current paper. Desazadesmethyldesferrithiocin can be structurally altered with facility, and data are already available on its iron-clearing properties and toxicity parameters. Four different kinds of structural modifications of this framework are undertaken: introduction of hydroxy, carboxy, or methoxy groups on the aromatic ring; alteration of the thiazoline ring; increasing the distance between the ligand donor atoms; and benz-fusion of the aromatic rings. The structural modifications described are shown to have a tremendous impact on both the iron clearance and toxicity profiles of the desazadesmethyldesferrithiocin molecule. All of the compounds are assessed in a bile-duct-cannulated rodent model to determine iron clearance efficiency. Ligands which demonstrate an efficiency of greater than 2% are carried forward to the iron-overloaded primate for iron-clearing measurements. Ligands with efficiencies greater than 3% in the primate are then evaluated in a formal toxicity study in rodents. On the basis of the results of the present work, 2-(2,4-dihydroxyphenyl)-Δ2-thiazoline-4(S)-carboxylic acid is a promising candidate for clinical evaluation.
- Bergeron, Raymond J.,Wiegand, Jan,Weimar, William R.,Vinson, J. R. Timothy,Bussenius, J?rg,Yao, Guo Wei,McManis, James S.
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- Improving FLC properties. Simplicity, planarity, and rigidity in new chiral oxazoline derivatives
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In an attempt to develop new dopants for improved ferroelectric properties in liquid crystals, aryloxazolines have been chosen as chiral moieties. They were prepared in optically active form from (S)-β-amino alcohols via a short stereospecific synthesis and incorporated into mesogenic systems. Mesogenic and ferroelectric properties of 11 compounds in five series of chiral oxazoline derivatives [I(OH), I(H), II(OH), II(H), and III(OH)] have been studied. In order to establish the relationship between the molecular structure and ferroelectric properties, an indepth structural investigation of both H-bonded and non-H-bonded phenyloxazoline moieties was carried out (by means of semiempirical calculations - AMI - and spectroscopic studies - IR, UV and 1H NMR). These studies have proved a planar structure for both types of structures, which should have a strong influence on ferroelectric properties. These properties have been evaluated in 10 mol % binary mixtures. The highest Ps values were measured for compounds of series I(OH) [P5 maxI(OH)a = 16.7 nC/cm2, Ps maxI(OH)b = 13.2 nC/cm2] containing a hydrogen bond, which makes the chiral part of the molecule more rigid. Compound III(OH)a shows a wide SmC* phase range which supercools well below room temperature, and it has been studied as a ferroelectric liquid crystal in the pure state. The Ps max measured is appreciably high: 225 nC/cm2. Its special thermal behavior (showing a glass transition at -28 °C) makes this compound very interesting from the point of view of practical applications and will be the target of further studies.
- Serrano, José Luis,Sierra, Teresa,González, Yolanda,Bolm, Carsten,Weickhardt, Konrad,Magnus, Angelika,Moll, Guido
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p. 8312 - 8321
(2007/10/03)
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- Herbicidal compounds
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A herbicidal compound of formula (I): STR1 wherein X is O, S(O)n or NRa where Ra is H or alkyl and n is 0, 1 or 2; R1 is H or halo; R2 is N or CR3 where R3 is halo or NO2 ; R4 is H, halo, NO2, alkyl, haloalkyl, CN, CO2 alkyl, cycloalkyl, phenyl, COalkyl, COphenyl, CHO,OH, NH2, NHCOalkyl or alkoxy R5 is H, halo or optionally substituted alkyl; R6 is H, halo or optionally substituted alkyl; provided that at least one of R5 and R6 is halo; R7 is CN, CHO, COOR8, CONR8 R9, where R8 is H, optionally substituted alkyl, alkenyl, alkynyl or aryl and R9 is a group R8, SO2 alkyl, NR10 R11 or N+ R10 R11 R12 Z- where Z is an agriculturally acceptable anion e.g. chloride and R10, R11 and R12 are independently selected from hydrogen and alkyl. Processes for the preparation of these compounds and compositions containing them are also described.
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