- A CONVENIENT FAMILY OF CHIRAL SHIFT REAGENTS FOR MEASUREMENT OF ENANTIOMERIC EXCESSES OF SULFOXIDES
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(R)(-)-N-(3,5-dinitrobenzoyl)-α-phenylethylamine is a good chiral shift reagent for sulfoxides such as Ar-(SO)-CH3 (Ar=substituted phenyl, naphtyl) or R-(SO)-CH3 (R=t-Bu,Cyclohexyl,n-Octyl). 1-Naphthyl propyl sulfoxide was also successfully resolved.The s
- Deshmukh, M.,Dunnach, E.,Juge, S.,Kagan, H. B.
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- New chiral stationary phases for liquid chromatography based on small molecules: Development, enantioresolution evaluation and chiral recognition mechanisms
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Recently, we reported the development of new chiral stationary phases (CSPs) for liquid chromatography (LC) based on chiral derivatives of xanthones (CDXs). Based on the most promising CDX selectors, 12 new CSPs were successfully prepared starting from suitable functionalized small molecules including xanthone and benzophenone derivatives. The chiral selectors comprising one, two, three, or four chiral moieties were covalently bonded to a chromatographic support and further packed into LC stainless-steel columns (150?×?2.1?mm I.D.). The enantioselective performance of the new CSPs was evaluated by LC using different classes of chiral compounds. Specificity for enantioseparation of some CDXs was observed in the evaluation of the new CSPs. Besides, assessment of chiral recognition mechanisms was performed by computational studies using molecular docking approach, which are in accordance with the chromatographic parameters. X-Ray analysis was used to establish a chiral selector 3D structure.
- Phyo, Ye' Zaw,Teixeira, Joana,Tiritan, Maria Elizabeth,Cravo, Sara,Palmeira, Andreia,Gales, Luís,Silva, Artur M.S.,Pinto, Madalena M.M.,Kijjoa, Anake,Fernandes, Carla
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- Preparation of two new diasteromeric chiral stationary phases based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid and (R)- or (S)-1-(1-naphthyl)ethylamine and chiral tethering group effect on the chiral recognition
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Two new diastereomeric chiral stationary phases (CSPs) based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid as a chiral tethering group and a Π-basic chiral unit such as (R)-1-(1-naphthyl) ethylamine (CSP 1) or (S)-1-(1-naphthyl)ethylamine (CSP 2) were prepared. The two CSPs were applied to the enantiomeric separation of N-(3,5-dinitrobenzoyl)-1-phenylalkylamines and N-(3,5-dinitrobenzoyl)-α-amino acid derivatives using 20% isopropyl alcohol in hexane as a normal mobile phase. To elucidate the effect of the two chiral units on the chiral recognition, the chiral recognition abilities of the two CSPs were compared with each other and with that of a CSP (CSP 3) based on (R)-1-(1-naphthyl)ethylamine. From the chromatographic chiral recognition results, (R)-1-(1-naphthyl)ethylamine and (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid constituting CSP 1 were concluded to show a cooperative ("matched") effect on the chiral recognition while (S)-1-(1-naphthyl)ethylamine and (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid constituting CSP 2 were concluded to show an uncooperative ("mismatched") effect on the chiral recognition. From these results, it was concluded that (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid can be successfully used as a chiral tethering group for the preparation of new CSPs.
- Agneeswari, Rajalingam,Sung, Ji Yeong,Jo, Eun Sol,Jeon, Hee Young,Tamilavan, Vellaiappillai,Hyun, Myung Ho
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- Synthesis and biological evaluation of substituted N-alkylphenyl-3,5- dinitrobenzamide analogs as anti-TB agents
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Here, a medicinal chemistry study of an N-alkylphenyl-3,5-dinitrobenzamide (DNB) scaffold as a potent anti-TB agent is presented. A series of chemical modifications were performed and forty-three new molecules were synthesized to study the structure-activity relationship (SAR) by evaluating against a sensitive strain (H37Rv) of Mycobacterium tuberculosis (MTB). Potent DNB analogs 4b, 7a, 7c, 7d, 7j, 7r and 9a were further tested against resistant strains of MTB. Their intracellular as well as bactericidal potential was also evaluated. Cytotoxicity and in vivo pharmacokinetic studies suggested that DNB analogs have an acceptable safety index, in vivo stability and bio-availability. From the present work, two compounds 7a and 7d have shown nanomolar to sub micro-molar MIC in extracellular and intracellular assays.
- Munagala, Gurunadham,Yempalla, Kushalava Reddy,Aithagani, Sravan Kumar,Kalia, Nitin Pal,Ali, Furqan,Ali, Intzar,Rajput, Vikrant Singh,Rani, Chitra,Chib, Reena,Mehra, Rukmankesh,Nargotra, Ami,Khan, Inshad Ali,Vishwakarma, Ram A.,Singh, Parvinder Pal
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p. 521 - 527
(2014/04/17)
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- Thiolates chemically induce redox activation of BTZ043 and related potent nitroaromatic anti-tuberculosis agents
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The development of multidrug resistant (MDR) and extensively drug resistant (XDR) forms of tuberculosis (TB) has stimulated research efforts globally to expand the new drug pipeline. Nitroaromatic compounds, including 1,3-benzothiazin-4-ones (BTZs) and related agents, are a promising new class for the treatment of TB. Research has shown that the nitroso intermediates of BTZs that are generated in vivo cause suicide inhibition of decaprenylphosphoryl- β-d-ribose 2′ oxidase (DprE1), which is responsible for cell wall arabinogalactan biosynthesis. We have designed and synthesized novel anti-TB agents inspired from BTZs and other nitroaromatic compounds. Computational studies indicated that the unsubstituted aromatic carbons of BTZ043 and related nitroaromatic compounds are the most electron-deficient and might be prone to nucleophilic attack. Our chemical studies on BTZ043 and the additional nitroaromatic compounds synthesized by us and others confirmed the postulated reactivity. The results indicate that nucleophiles such as thiolates, cyanide, and hydride induce nonenzymatic reduction of the nitro groups present in these compounds to the corresponding nitroso intermediates by addition at the unsubstituted electron-deficient aromatic carbon present in these compounds. Furthermore, we demonstrate here that these compounds are good candidates for the classical von Richter reaction. These chemical studies offer an alternate hypothesis for the mechanism of action of nitroaromatic anti-TB agents, in that the cysteine thiol(ate) or a hydride source at the active site of DprE1 may trigger the reduction of the nitro groups in a manner similar to the von Richter reaction to the nitroso intermediates, to initiate the inhibition of DprE1.
- Tiwari, Rohit,Moraski, Garrett C.,Krchňák, Viktor,Miller, Patricia A.,Colon-Martinez, Mariangelli,Herrero, Eliza,Oliver, Allen G.,Miller, Marvin J.
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supporting information
p. 3539 - 3549
(2013/04/23)
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- Chiral porphyrin dimer with a macrocyclic cavity for intercalation of aromatic guests
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Chiral diporphyrin receptor 1, which has a macrocyclic cavity to sandwich aromatic guest molecules via double π-π stacking interactions, enabled the naked-eye detection of an aromatic explosive as well as chiral discrimination in NMR.
- Ema, Tadashi,Ura, Norichika,Eguchi, Katsuya,Ise, Yuhei,Sakai, Takashi
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supporting information; scheme or table
p. 6090 - 6092
(2011/08/02)
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- COMPOSITIONS AND METHODS FOR CYCLOFRUCTANS AS SEPARATION AGENTS
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The present invention relates to derivatized cyclofructan compounds, compositions comprising derivatized cyclofructan compounds, and methods of using compositions comprising derivatized cyclofructan compounds for chromatographic separations of chemical species, including enantiomers. Said compositions may comprise a solid support and/or polymers comprising derivatized cyclofructan compounds.
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Page/Page column 45-49; 57
(2010/12/31)
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- NEW CHIRAL STATIONARY PHASES FOR CHROMATOGRAPHY BASED ON AROMATIC ALLYL AMINES
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New chiral stationary phases (CSPs) based on chiral selectors covalently bound on a solid support were prepared. Chiral selectors were obtained from enantiomerically pure aromatic amines and 3,5-dinitrobenzoic acid and then linked to the support surface through the allylic double bond. Such obtained materials allow enantioseparation of racemates or enantiomerically enriched compounds. These chiral stationary phases can be used as fillings in chromatographic columns for enantiomer separation of naproxen type drugs and other similar non-steroidal anti-inflammatory drugs (NSAID) by means of high performance liquid chromatography on both the analytical and preparative scale.
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Page/Page column 16-17
(2009/10/22)
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- Development of new HPLC chiral stationary phases based on native and derivatized cyclofructans
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An unusual class of chiral selectors, cyclofructans, is introduced for the first time as bonded chiral stationary phases. Compared to native cyclofructans (CFs), which have rather limited capabilities as chiral selectors, aliphatic-and aromatic-functionalized CF6s possess unique and very different enantiomeric selectivities. Indeed, they are shown to separate a very broad range of racemic compounds. In particular, aliphatic-derivatized CF6s with a low substitution degree baseline separate all tested chiral primary amines. It appears that partial derivatization on the CF6 molecule disrupts the molecular internal hydrogen bonding, thereby making the core of the molecule more accessible. In contrast, highly aromaticfunctionalized CF6 stationary phases lose most of the enantioselective capabilities toward primary amines, however they gain broad selectivity for most other types of analytes. This class of stationary phases also demonstrates high "loadability" and therefore has great potential for preparative separations. The variations in enantiomeric selectivity often can be correlated with distinct structural features of the selector. The separations occur predominantly in the presence of organic solvents.
- Sun, Ping,Wang, Chunlei,Breitbach, Zachary S.,Zhang, Ying,Armstrong, Daniel W.
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experimental part
p. 10215 - 10226
(2010/05/01)
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- Chiral self-discrimination of the enantiomers of α-phenylethylamine derivatives in proton NMR
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Two types of chiral analytes, the urea and amide derivatives of α-phenylethylamine, were prepared. The effect of inter- molecular hydrogen-bonding interaction on self-discrimination of the enantiomers of analytes has been investigated using high-resolutio
- Huang, Shao-Hua,Bai, Zheng-Wu,Feng, Ji-Wen
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experimental part
p. 423 - 427
(2010/04/05)
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- The Stereochemical Course of Migration from Phosphorus to Nitrogen in the Photo-Curtius Rearrangement of Phosphinic Azides (Harger Reaction)
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The homochiral phosphinic azides (R,R)-1 and (S,S)-1 have been prepared in enantiomerically pure form by resolution of diastereomeric phosphinamides derived from (S)-1-phenylethylamine and (R)-phenylglycine.Irradiation of the azides in methanol induced a photo-Curtius rearrangement of phosphonamidates in which the stereogenic carbon unit migrated to a nitrogen atom.Hydrolysis of the phosphonamidates produced 1-phenylethylamine, which was 99.0percent ee and of the same configuration as the carbon unit in the starting azide (99.0percent net retention).The implication for asymmetric synthetic methodology is discussed.
- Denmark, Scott E.,Dorow, Roberta L.
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- 3,5-DINITROBENZAMIDES AS CHIRAL ELECTRON ACCEPTORS
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The synthesis of new readily obtainable electron acceptors of the amide type labeled with optically active α-phenylethylamine was realized.Their spectral and chiral-optical characteristics were studied.It was established that they can be used as chiral electron acceptors for the preparative resolution of compounds through diastereomeric charge-transfer complexes.A valuable characteristic of the synthesized electron acceptors is their strong attachment to the support under the conditions of resolution.
- Il'ina, I. G.,Ivanova, E. V.,Vlasova, O. G.,Nozdrina, V. A.,Potapov, V. M.
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p. 1943 - 1946
(2007/10/02)
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