Asymmetric allylation of α-ketoester-derived N-benzoylhydrazones promoted by chiral sulfoxides/N-oxides Lewis bases: highly enantioselective synthesis of quaternary α-substituted α-allyl-α-amino acids.

abstract：:The epimeric diterpenes (+)-(1S,3E,7E,11S,12S)-verticilla-3,7-dien-12-ol (1), isolated from Bursera suntui, and (+)-(1S,3E,7E,11S,12R)-verticilla-3,7-dien-12-ol (2), isolated from Bursera kerberi, gave the same Wagner-Meerwein rearrangement product (-)-(1E,4Z,8Z,11S,12R)-phomacta-1,(15)4,8-triene (3). The Et2 O:BF3 -i...

journal_title：Chirality

authors： Del Río-Chávez ÁA,García-Gutiérrez HA,Román-Marín LU,Beiza-Granados L,Cerda-García-Rojas CM,Joseph-Nathan P,Hernández-Hernández JD

更新日期：2019-11-01 00:00:00

abstract：:Synthetic pyrethroid insecticides are chiral compounds with multiple asymmetric positions. In this study, isomers of four commonly used pyrethroids were separated at the enantiomeric level by enantioselective high-performance liquid chromatography (HPLC), and differences between enantiomers in aquatic toxicity were ch...

journal_title：Chirality

authors： Liu W,Gan JJ,Qin S

更新日期：2005-01-01 00:00:00

abstract：:Compound A, a novel disubstituted pyrrolidine acid, is a member of a new class of agents that are potentially useful for the treatment of diabetes and dyslipidemia. The absolute configuration of this compound was determined by using vibrational circular dichroism (VCD). The results are in agreement with the assignment...

journal_title：Chirality

authors： Freedman TB,Cao X,Phillips LM,Cheng PT,Dalterio R,Shu YZ,Zhang H,Zhao N,Shukla RB,Tymiak A,Gozo SK,Nafie LA,Gougoutas JZ

更新日期：2006-09-01 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：: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：:The influence of latent heat dissipated by the crystallization of 1,1'-binaphthyl in its supercooled molten state on the chiral symmetry breaking transition was investigated. Temperature change in the crystallization system was monitored by infrared thermocamera. Temperature rise due to the dissipation of latent heat ...

journal_title：Chirality

authors： Asakura K,Hayashi M,Osanai S

更新日期：2003-03-01 00:00:00

abstract：:The measurement of optical rotation (OR) and optical rotatory dispersion has been finding renewed interest for some years, because of advancement in computational methods and in the performance of new experiments. Here, we shortly review the traditional and most-used experimental methods. We define and discuss the two...

journal_title：Chirality

authors： Castiglioni E,Abbate S,Longhi G

更新日期：2011-10-01 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：:A rapid and simple procedure for enantioselective preparation of 2- and 3-substituted 2,3-dihydro[1,4]dioxino[2,3-b]pyridine derivatives (A and B, respectively) is described. The enantiomeric purity of each isomer was determined by capillary electrophoresis using a dual-cyclodextrin system (S-beta-CD/beta-CD) dissolve...

journal_title：Chirality

authors： Lazar S,Soukri M,El Haddad M,Akssira M,Leger JM,Jarry C,Morin P,Guillaumet G

更新日期：2005-01-01 00:00:00

abstract：:A variety of reactions can be categorized under the global concept of the "interconversion of stereoisomers." Thus, racemization or epimerization can result from inversion of labile chiral centers. From the examples available, some predictive rules are suggested for a chiral center of the type R"R'RC-H undergoing base...

journal_title：Chirality

authors： Testa B,Carrupt PA,Gal J

更新日期：1993-01-01 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：:The UV absorption and electronic circular dichroism (ECD) spectra of (R)- and (S)-nicotine and (S)-nornicotine in aqueous solution were measured to a significantly lower wavelength range than previously reported, allowing the identification of four previously unobserved electronic transitions. The ECD spectra of the t...

journal_title：Chirality

authors： Clayton PM,Vas CA,Bui TT,Drake AF,McAdam K

更新日期：2013-05-01 00:00:00

abstract：:The enantioselective hydrogenation of methyl or ethyl pyruvate over cinchona-platinum catalyst system (Orito's reaction) is one of the most intensively studied heterogeneous catalytic asymmetric hydrogenation reactions. Studies aiming at systematic changes of the chiral template have played a crucial role in creating ...

journal_title：Chirality

authors： Tálas E,Margitfalvi JL

更新日期：2010-01-01 00:00:00

abstract：:In modern chromatography, chiral stationary phase (CSP) and enantiomer self-disproportionation (ESD) are new inventions of packing material offer a guarantee for a successful enantiomeric separation. All CSPs were synthesized by chemical bonding of the relevant organic moieties onto a porous parent silica material for...

journal_title：Chirality

authors： Mayani VJ,Abdi SH,Mayani SV,Kim HC,Park SK

更新日期：2011-04-01 00:00:00

abstract：:The aim of our study was to synthesize vinylic and pyrido-fused pyridazines with a spirano moiety and to investigate their stereochemistry by spectroscopic and HPLC analyses. The vinylic compounds 5 were obtained by Knoevenagel condensation of cyclohexylidene malonates 1 with pyridazinecarbaldehyde 2. Compound 5b exhi...

journal_title：Chirality

authors： Beke G,Gergely A,Szász G,Szentesi A,Nyitray J,Barabás O,Harmath V,Mátyus P

更新日期：2002-05-15 00:00:00

abstract：:Many drugs contain a chiral centre, or such a centre is introduced during metabolism of the drug in man and in animals. If a single chiral centre is present, the drug will normally exist as a mixture of two enantiomers, of which one may have quite different pharmacologic and/or toxic effects than the other. Chiral dru...

journal_title：Chirality

authors： Coutts RT,Baker GB

更新日期：1989-01-01 00:00:00

abstract：:6-Fluoro-2-methyl-1,2,3,4-tetrahydroquinoline (FTHQ) enantiomers were separated by supercritical fluid extraction using carbon dioxide. Diastereoisomeric salts were formed from the racemic base with less than one equivalent of O,O'-di-(4-toluoyl)-(2R,3R)-tartaric acid (DPTTA). Further purification was achieved by part...

journal_title：Chirality

authors： Kmecz I,Simándi B,Bálint J,Székely E,Fogassy E,Kemény S

更新日期：2001-01-01 00:00:00

abstract：:Spontaneous symmetry breaking in reactive systems, known as a rare physical phenomenon and for the Soai autocatalytic irreversible reaction, might in principle also occur in other, more common asymmetric reactions when the chiral product is capable to promote its formation and an element of "nonlinearity" is involved ...

journal_title：Chirality

authors： Mauksch M,Tsogoeva SB,Wei S,Martynova IM

更新日期：2007-11-01 00:00:00

abstract：:This paper reports the enantioseparation of β-hydroxy-1,2,3-triazole derivatives, which present a broad range of biological properties, by supercritical fluid chromatography (SFC) and high-performance liquid chromatography techniques (HPLC). Polysaccharide-based chiral columns (cellulose and amylose) were used to eval...

journal_title：Chirality

authors： Alvarenga N,Porto ALM,Barreiro JC

更新日期：2018-07-01 00:00:00

abstract：:Achiral 4-isopropyltropolone methyl ether (3) included in an optically active host compound (-)-1 yielded optically active photocyclization products (-)-5 and (-)-6 in 96 and 90% ee, respectively, upon photoirradiation in the solid state. ...

journal_title：Chirality

authors： Tanaka K,Nagahiro R,Urbanczyk-Lipkowska Z

更新日期：2002-07-01 00:00:00

abstract：:Both epimers of the naturally occurring nonproteinogenic amino acid L-cyclopentenylglycine, (2S,1'S)- and (2S, 1'R)-2-(cyclopent-2'-enyl)glycine, were obtained via a procedure involving condensation of 3-chlorocyclopentene with diethyl acetylaminomalonate, deethoxycarbonylation, chromatographic separation of the resul...

journal_title：Chirality

authors： Andersen L,Nielsen B,Jaroszewski JW

更新日期：2000-10-01 00:00:00

abstract：:E-6087 is a nonsteroidal anti-inflammatory compound that selectively inhibits cyclooxygenase-2. Because E-6087 has a chiral center, this compound is a racemic mixture of two stereoisomers, (+)-(R)-E-6087 (E-6231) and (-)-(S)-E-6087 (E-6232). A normal-phase liquid-chromatographic method for the enantioselective determi...

journal_title：Chirality

authors： Salgado L,Encina G,Farran R,Puig S,Martínez L

更新日期：2004-05-15 00:00:00

abstract：:Experimental hyperlipidemia has shown to decrease cytochrome P450 3A4 and 2C11 expression and to increase liver concentrations and the plasma protein binding of halofantrine (HF) enantiomers. The present study examined the effect of hyperlipidemic (HL) serum on the metabolism of HF enantiomers by primary rat hepatocyt...

journal_title：Chirality

authors： Patel JP,Hamdy DA,El-Kadi AO,Brocks DR

更新日期：2012-07-01 00:00:00

abstract：:The application of the Cartesian coordinate tensor transfer (CCT) technique for simulations of the IR absorption and vibrational circular dichroism (VCD) spectra of relatively large nucleic acid fragments is demonstrated on several case studies. The approach is based on direct ab initio calculations of atomic tensors,...

journal_title：Chirality

authors： Andrushchenko V,Bouř P

更新日期：2010-01-01 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：:The electronic circular dichroism (ECD) spectra of two sesquiterpenoids (1 and 2) related to oplopanone, obtained from a methanolic extract of the plant Serphidium stenocephalum (Artemisia stenocephala), were measured and reproduced by means of time-dependent density functional theory (TDDFT) calculations, establishin...

journal_title：Chirality

authors： Shafiq N,Saleem M,Riaz N,Tousif MI,Jabbar A,Tareen RB,Pescitelli G

更新日期：2014-01-01 00:00:00

abstract：:Ropivacaine hydrochloride monohydrate (ropivacaine) is a new local anaesthetic agent which is administered exclusively as the (-)-(S)-form. The aim of the study was to determine whether metabolic racemisation of (-)-(S)-ropivacaine occurs. This was tested in man, rat, dog, and sheep after different routes of administr...

journal_title：Chirality

authors： Arvidsson T,Bruce HF,Halldin MM

更新日期：1995-01-01 00:00:00

abstract：:The five-steps synthesis of a hemicryptophane cage combining a benzene-1,3,5-tricarboxamide unit and a cyclotriveratrylene (CTV) moiety is described. Chiral high-performance liquid chromatography (HPLC) was used to resolve the racemic mixture. The absolute configuration of the isolated enantiomers was assigned by comp...

journal_title：Chirality

authors： Long A,Jean M,Albalat M,Vanthuyne N,Giorgi M,Górecki M,Dutasta JP,Martinez A

更新日期：2019-11-01 00:00:00

abstract：:The R enantiomers of some of the 2-arylpropionic acid non-steroidal antiinflammatory drugs (NSAIDs) are known to undergo metabolic chiral inversion to their more pharmacologically active antipodes. This process is drug and species dependent and usually unidirectional. The S to R chiral inversion, on the other hand, is...

journal_title：Chirality

authors： Jamali F,Lovlin R,Aberg G

更新日期：1997-01-01 00:00:00

abstract：:Flurbiprofen is a kind of nonsteroidal anti-inflammatory drug, which has been widely used in clinic for treatment of rheumatoid arthritis and osteoarthritis. It has been reported that S-flurbiprofen shows good performance on clinic anti-inflammatory treatment, while R-enantiomer almost has no pharmacological activitie...

journal_title：Chirality

authors： Cui X,Ding Q,Shan RN,He CH,Wu KJ

更新日期：2019-06-01 00:00:00