Chiral separation and CD characterisation of enantiomeric cyclotriphosphazene derivatives.

abstract：:Methods for the resolution of (+/-)-1-methyl-7-oxabicyclo[2.2.1]heptan-2-one 1, a versatile chiral building block for terpenoids, have been investigated. While no efficient result was obtained with kinetic resolution methods, both enantiomers of 1 were prepared optically pure for the first time via esterification of t...

journal_title：Chirality

authors： Guan YK,Li YL

更新日期：2005-02-01 00:00:00

abstract：:The first direct asymmetric synthetic preparation of trifluoro-1-(indol-3-yl)ethanols (TFIEs) is described by an enantioselective organocatalytic method from indoles and inexpensive trifluoroacetaldehyde methyl hemiacetal. The reaction is catalyzed by hydroquinine to produce TFIEs in an almost quantitative yield and w...

journal_title：Chirality

authors： Borkin DA,Landge SM,Török B

更新日期：2011-09-01 00:00:00

abstract：:According to the Ibuprofen Product-Specific Bioequivalence Guidance of the European Medicines Agency, achiral bioanalytical methods are considered acceptable for demonstration of bioequivalence of ibuprofen-containing products. The aim of this investigation is to compare the bioequivalence outcomes obtained with indiv...

journal_title：Chirality

authors： González-Rojano E,Marcotegui J,Laredo L,Gwaza L,Gordon J,Portolés A,Vargas E,Morales-Alcelay S,García-Arieta A

更新日期：2020-09-01 00:00:00

abstract：:The biodegradation of the chiral phenoxyalkanoic herbicides 2-(2,4-dichlorophenoxy)propionic aid (2,4-DP) and 2-(4-chloro-2-methylphenoxy)propionic acid (MCPP) was investigated using enantioselective HPLC and chiroptical detection. Racemic mixtures of 2,4-DP and MCPP were applied to three species of turf grass, four s...

journal_title：Chirality

authors： Schneiderheinze JM,Armstrong DW,Berthod A

更新日期：1999-01-01 00:00:00

abstract：:[3β,5β,7α,12α]-3-(4-t-Butylbenzoilamine)-7,12-dihydroxycholan-24-oic acid was synthesized and recrystallized from chlorobenzene and acetone. Orthorhombic P2(1)2(1)2(1) and monoclinic P2(1) crystals were obtained, respectively, and both crystals include solvent and water molecules with a 1:1:1 stoichiometry. In the sec...

journal_title：Chirality

authors： Meijide F,Trillo JV,Soto VH,Jover A,Tato JV

更新日期：2011-11-01 00:00:00

abstract：:The versatility of a previously developed method for the synthesis of chiral carbene-based palladacycles is demonstrated through the synthesis of two new chiral pyridine-functionalized N-heterocyclic carbene palladacycles with different wingtip groups. The efficiency in their resolution with different counter anions a...

journal_title：Chirality

authors： Ng KH,Li Y,Tan WX,Chiang M,Pullarkat SA

更新日期：2013-03-01 00:00:00

abstract：:Subcellular fractions of three human brain specimens were found to contain esterase activities which hydrolyzed racemic oxazepam 3-acetate (rac-OXA). All three human brain preparations were highly selective toward the S-enantiomer of rac-OXA. ...

journal_title：Chirality

authors： Yang SK,Huang A,Huang JD

更新日期：1993-01-01 00:00:00

abstract：:Herein, we present the solution-state NMR studies on dextromethorphan (1) under both isotropic and anisotropic conditions. From the measurement of 22 residual dipolar couplings using a stretched polystyrene gel (PS), we show that accurate and detailed structural information is readily determined including the relative...

journal_title：Chirality

authors： Swarbrick JD,Ashton TD

更新日期：2010-01-01 00:00:00

abstract：:Acyl glucuronides formed from carboxylic acids can undergo hydrolysis, acyl migration, and covalent binding to proteins. In buffers at physiological pH, the degradation of acylglucuronide of a chiral NSAID, carprofen, consisted mainly of acyl migration. Acidic pH reduced hydrolysis and acyl migration, thus stabilizing...

journal_title：Chirality

authors： Georges H,Presle N,Buronfosse T,Fournel-Gigleux S,Netter P,Magdalou J,Lapicque F

更新日期：2000-02-01 00:00:00

abstract：:An improved synthesis of the enantiomers of the new benzofurane-type antiarrhythmic compound 1 is described, which makes use of the enantiomerically pure mbe-lactol. Thus, acylation of the benzofurane 4 with acetic anhydride and subsequent bromination gave the bromoacetyl-derivative 6, which, after reduction with LiAl...

journal_title：Chirality

authors： Ecker G,Fleischhacker W,Helml T,Noe CR,Scasny S,Lemmens-Gruber R,Studenik C,Marei H,Heistracher P

更新日期：1994-01-01 00:00:00

abstract：:The novel chiral spirobipyridopyrans 1 and 2 were synthesized by the acid catalyzed aldol type condensation of 5-deoxypyridoxal with the appropriate ketone and subsequent reaction of the resulting pyrylium salt with base. The indolinospiropyridopyrans 3-5, which contain the modified B(6) unit, were prepared by aldol r...

journal_title：Chirality

authors： Loncar-Tomaskovic L,Pustet N,Mrvos-Sermek D,Nagl A,Mintas M,Mannschreck A

更新日期：2001-02-01 00:00:00

abstract：:Four Ala-Ala dipeptides with a perfluoroalkyl chain at the N-terminal were synthesized. They were able to self-assemble into helical nanofibers and/or twisted nanobelts in a mixture of DMSO/H2 O. The handedness of nanofibers and nanobelts was controlled by the chirality of the alanine at the N-terminal. The stacking h...

journal_title：Chirality

authors： Zhang L,Lin S,Tong Q,Li Y,Wang Y,Li Y,Li B,Yang Y

更新日期：2019-11-01 00:00:00

abstract：:Benalaxyl (BX), methyl-N-phenylacetyl-N-2,6-xylyl alaninate, is a potent acylanilide fungicide and consist of a pair of enantiomers. The stereoselective metabolism of BX was investigated in rat and rabbit microsomes in vitro. The degradation kinetics and the enantiomer fraction (EF) were determined using normal high-p...

journal_title：Chirality

authors： Zhang P,Zhu W,Dang Z,Shen Z,Xu X,Huang L,Zhou Z

更新日期：2011-02-01 00:00:00

abstract：:A summary of selected NMR studies of enantiodiscrimination phenomena regarding the use of quinine-based chiral solvating agents (CSAs) for the determination of the enantiomeric compositions in solution is reported, with explanations of their multireceptorial character offered. ...

journal_title：Chirality

authors： Uccello-Barretta G,Balzano F,Salvadori P

更新日期：2005-01-01 00:00:00

abstract：:A method is described for the HPLC analysis of oxamniquine enantiomers in liver fraction incubates, using a second-generation alpha 1-acid glycoprotein-based column (Chiral-AGP). Oxamniquine is extracted from the incubation media by liquid-liquid extraction, using diethyl ether. The dried residue is redissolved in elu...

journal_title：Chirality

authors： Noctor TA,Fell AF,Kaye B

更新日期：1990-01-01 00:00:00

abstract：:The synthesis of the eight stereoisomers of muscarine has been efficiently accomplished by utilizing the two enantiomers of lactic esters as starting material. The synthetic strategy is based on a SnCl4-catalyzed addition of allyltrimethylsilane to O-protected lactic aldehydes followed by an iodocyclization process. A...

journal_title：Chirality

authors： De Amici M,Dallanoce C,De Micheli C,Grana E,Dondi G,Ladinsky H,Schiavi G,Zonta F

更新日期：1992-01-01 00:00:00

abstract：:Massarigenin A (1) and papyracillic acids A (2) and B (3) were isolated from the endophytic fungus Microsphaeropsis sp. Their structures were elucidated by multidimensional nuclear magnetic resonance spectroscopy; the structure of massarigenin A (1) was also confirmed by X-ray crystallography. The absolute configurati...

journal_title：Chirality

authors： Hussain H,Ahmed I,Schulz B,Draeger S,Flörke U,Pescitelli G,Krohn K

更新日期：2011-09-01 00:00:00

abstract：:In order to cope with the increasing number of publications on the separation of enantiomers by chromatography on a chiral stationary phase, the graphical molecular database CHIRBASE was created. In the present state, the database package covers information (structural, bibliographic, and chromatographic data) on liqu...

journal_title：Chirality

authors： Koppenhoefer B,Nothdurft A,Pierrot-Sanders J,Piras P,Popescu C,Roussel C,Stiebler M,Trettin U

更新日期：1993-01-01 00:00:00

abstract：:Stereoselectivity in the renal secretion of carbenicillin (CBPC) was studied in rabbits. Significant renal secretion of CBPC was observed in vivo, with the secretion of the S-epimer being greater than that of the R-epimer. Stereoselective transport of CBPC was further studied in vitro using basolateral and brush borde...

journal_title：Chirality

authors： Itoh T,Nakaura H,Koyano S,Tsuda Y,Yamada H

更新日期：1998-01-01 00:00:00

abstract：:Conditions for separation of enantiomers of a mandelic acid derivative, methyl 2-phenyl-2-(tetrahydropyranyloxy) acetate (the analyte) were studied. Because of the presence of two chiral carbons, the analyte consists of four stereoisomers stable at ambient temperature. Chiral HPLC of the analyte resulted in four peaks...

journal_title：Chirality

authors： Shen B,Xu X,Chen J,Zhang X,Xu B

更新日期：2006-09-01 00:00:00

abstract：:Perfluorooctane sulfonate (PFOS) is one of the most frequently detected perfluoroalkyl substances in environmental and human samples. Previous studies have shown that nonracemic PFOS in biological samples can be used as a marker of PFOS exposure sources. In recent years, supercritical fluid chromatography (SFC) has em...

journal_title：Chirality

authors： Zhao L,Chen F,Guo F,Liu W,Liu K

更新日期：2019-10-01 00:00:00

abstract：:An enantiocontrolled total synthesis of 19,20-dihydroakuammicine using a catalytic asymmetric Michael addition of dimethyl malonate to cyclohexenone as the key step is described. The above catalytic asymmetric Michael addition proceeds quite efficiently in the presence of a heterobimetalic asymmetric catalyst (ALB-KO-...

journal_title：Chirality

authors： Ohori K,Shimizu S,Ohshima T,Shibasaki M

更新日期：2000-06-01 00:00:00

abstract：:Chiral sulfoxides/N-oxides (R)-1 and (R,R)-2 are effective chiral promoters in the enantioselective allylation of α-keto ester N-benzoylhydrazone derivatives 3a-g to generate the corresponding N-benzoylhydrazine derivatives 4a-g, with enantiomeric excesses as high as 98%. Representative hydrazine derivatives 4a-b were...

journal_title：Chirality

authors： Reyes-Rangel G,Bandala Y,García-Flores F,Juaristi E

更新日期：2013-09-01 00:00:00

abstract：:The concentration sensitivity of a racemic drug (chlorpheniramine maleate) in chiral capillary electrophoresis with electrospray ionization – mass spectrometric detection was improved ~500-fold via stacking. Enantiomeric separation was achieved through the use of a neutral chiral pseudostationary phase (2-hydroxpropyl...

journal_title：Chirality

authors： Wuethrich A,Haddad PR,Quirino JP

更新日期：2014-11-01 00:00:00

abstract：:The programmed assembly of p-octiphenyl rods carrying six complementary tripeptide strands was studied in the presence of bilayer membranes using circular dichroism (CD) spectroscopy. Thermal CD experiments demonstrated programmed assembly of anionic and cationic rods into supramolecules at low temperature that irreve...

journal_title：Chirality

authors： Sakai N,Matile S

更新日期：2004-01-01 00:00:00

abstract：:Several biologically active compounds structurally include the enantiopure 2-substituted-1,4-benzodioxane scaffold. The straightforward racemization that affects reactions involving most of the common chemical reactives is thus a crucial issue. The developing of a completely stereo-controlled synthetic route that does...

journal_title：Chirality

authors： Straniero V,Casiraghi A,Fumagalli L,Valoti E

更新日期：2018-07-01 00:00:00

abstract：:4-l-menthyloxycarbonyl 5-aryl prolinates were studied as organocatalysts of a novel three-component reaction of cyclohexanone, benzoic acid, and β-nitrostyrene. The presence of ortho-halogen atom in 5-aryl fragment of the catalyst is favored for driving the formation of chiral 7a-hydroxyoctahydro-2H-indol-2-one scaffo...

journal_title：Chirality

authors： Ivantcova PM,Kudryavtsev KV

更新日期：2020-06-01 00:00:00

abstract：:Human carboxylesterase 1 (hCES1) is an enzyme that plays an important role in hydrolysis of pharmaceuticals in the human liver. In this study, elucidation of the chiral recognition ability of hCES1 was attempted using indomethacin esters in which various chiral alcohols were introduced. Indomethacin was condensed with...

journal_title：Chirality

authors： Takahashi M,Takani D,Haba M,Hosokawa M

更新日期：2020-01-01 00:00:00

abstract：:The size, sign, and profile of induced circular dichroism (CD) features in the Soret region are reliable indicators of the binding modes of porphyrins and metalloporphyrins to DNA. Porphyrins shown (using such CD criteria) to be intercalators in monodispersed DNA duplexes prove extremely useful for the detection and c...

journal_title：Chirality

authors： Pasternack RF

更新日期：2003-05-05 00:00:00

abstract：:We report a method to determine the absolute configuration of alpha-amino acids by exciton coupled circular dichroism (ECCD). Naturally occurring amino acids were successfully derivatized with 2-bromomethylquinoline. Complexation of these conformationally flexible ligands with Cu(II) salts yielded defined propeller-li...

journal_title：Chirality

authors： Holmes AE,Zahn S,Canary JW

更新日期：2002-06-01 00:00:00