Resolution Of Cis Research Articles

An improved synthesis and resolution of cis- and trans-2,3-diphenyl morpholines

An improved procedure for the synthesis of cis- and trans-2,3-diphenyl morpholines with good overall yield is described. The stereoisomers were efficiently resolved through the corresponding diastereomeric salts using tartaric acid and ( R)-mandelic acid.

Separation and identification of cis and trans isomers of 2-butene-l,4-diol and lafutidine by HPLC and LC-MS

The cis and trans isomers separation of 2-butene-1,4-diol and lafutidine were studied by HPLC on two kinds of chiral columns: (S,S)-Whelk-O 1 and ChiraSpher. The isomers of 2-butene-1,4-diol can be separated on both chiral columns while the isomers of lafutidine can only be resolved on ChiraSpher column. The influence of different type and amount of mobile phase modifier on the isomers separation was extensively studied. The resolution of cis and trans isomers of 2-butene-1,4-diol was 2.61 on (S,S)-Whelk-O 1 column with hexane-ethanol (97:3, v/v) as the mobile phase. The resolution of lafutidine was 1.89 on ChiraSpher column with hexane-ethanol-THF-diethylamine (92:3:5:0.1, v/v/v/v) as the mobile phase. LC-MS methods were developed to identify the isomer peaks.

Stereoselective determination of allethrin by two-dimensional achiral/chiral liquid chromatography with ultraviolet/circular dichroism detection

A two-dimensional achiral/chiral HPLC method with circular dichroism (CD) detection was optimized for the stereochemical resolution and determination of the elution order of the eight stereoisomers of synthetic allethrin. A monolithic silica HPLC column (Chromolith, Merck, 100 mm × 4.6 mm i.d.) was put orthogonally to an enantioselective OJ Daicel column (250 mm × 4.6 mm i.d.) by means of a switching valve. The resolution of cis and trans diastereoisomers on the silica column was obtained by using a mobile phase consisting of n-hexane:tert-butyl methyl ether (96:4) (v/v) at a flow rate of 1 ml min−1. The cis and trans peaks were then switched to the enantioselective OJ column separately in two subsequent injections. The resolution of the four trans stereoisomers was accomplished by using n-hexane:tert-butyl methyl ether (90:10) (v/v), while the mobile phase composition for the four cis stereoisomers consisted of n-hexane:isopropanol (99.3:0.7) (v/v). The CD based detection system allowed the determination of the elution order on the basis of the CD signals of the single stereoisomers, together with the injection of pure stereoisomers. Under the final conditions, the validated method was applied to the determination of stereoisomeric composition and absolute configuration of the prevailing stereoisomers of real samples, i.e. commercial batches of different sources of d-allethrin.

Stereoselective determination of allethrin by two-dimensional achiral/chiral liquid chromatography with ultraviolet/circular dichroism detection

A two-dimensional achiral/chiral HPLC method with circular dichroism (CD) detection was optimized for the stereochemical resolution and determination of the elution order of the eight stereoisomers of synthetic allethrin. A monolithic silica HPLC column (Chromolith, Merck, 100 mm × 4.6 mm i.d.) was put orthogonally to an enantioselective OJ Daicel column (250 mm × 4.6 mm i.d.) by means of a switching valve. The resolution of cis and trans diastereoisomers on the silica column was obtained by using a mobile phase consisting of n-hexane: tert-butyl methyl ether (96:4) (v/v) at a flow rate of 1 ml min −1. The cis and trans peaks were then switched to the enantioselective OJ column separately in two subsequent injections. The resolution of the four trans stereoisomers was accomplished by using n-hexane: tert-butyl methyl ether (90:10) (v/v), while the mobile phase composition for the four cis stereoisomers consisted of n-hexane:isopropanol (99.3:0.7) (v/v). The CD based detection system allowed the determination of the elution order on the basis of the CD signals of the single stereoisomers, together with the injection of pure stereoisomers. Under the final conditions, the validated method was applied to the determination of stereoisomeric composition and absolute configuration of the prevailing stereoisomers of real samples, i.e. commercial batches of different sources of d-allethrin.

High resolution packed column supercritical fluid chromatography of fatty acid methyl esters

A wide range of methyl esters of saturated and unsaturated fatty acids from C16 to C24 has been separated by supercritical fluid chromatography on a packed silica column. The retention times were primarily dependent on the number of double bonds and the chain length of the parent acid had a negligible influence. The efficiency and resolution of cis- and trans-isomers of C18 and C22 esters were examined on linked columns from 25 to 175 cm overall length. Improvements were obtained up to 125 cm but the effects were limited by increases in the back pressure.

Cis- and trans-2,3,3a,4,5,9b-Hexahydro-1 H-benz[ e]indoles: synthesis and evaluation of dopamine D 2 and D 3 receptor binding affinity

cis- and trans-2,3,3a,4,5,9b-Hexahydro-1 H-benz[ e]indoles were synthesized as conformationally rigid analogues of 3-phenylpyrrolidine and evaluated for dopamine (DA) D 2S and D 3 receptor binding affinity. The tricyclic benz[ e]indole nucleus was constructed by a previously reported reductive amination-cyclization procedure. Several unexpected side products were isolated and characterized using the general method. The trans-diastereoisomers exhibited greater affinities for the DA D 3 receptor than the corresponding cis-isomers. In both the cis- and trans- series the greatest affinity for DA D 3 receptors was shown by compounds substituted with N- n-propyl or N-allyl groups. The cis-(±)- N-allyl derivative 21e demonstrated a D 2S/D 3 selectivity of 290. Resolution of cis-(±)- 5 and trans-(±)- 21c into individual enantiomers showed that in both series the more active isomer had 3a R absolute configuration. These novel ligands may be useful tools for gaining additional information about the DA D 3 receptor.

The resolution of cis-[Ru(phen) 2(CH 3CN) 2] 2+ (phen = 1,10-phenanthroline), and its use in the synthesis of chiral cis-[Ru(phen) 2X 2] n+ species ( n = 0, 2; X = CN −, Cl −, py)

A convenient general method is described for the isolation of optically active ruthenium(II) complexes, cis-[Ru(phen) 2X 2] n+ . The resolution strategy involves the initial preparation of the Δ and Λ isomers of cis-[Ru(phen) 2(CH 3CN) 2](PF 6) 2. These precursor compounds were characterized by UV-Vis, 1H NMR and CD spectral analysis, while enantiomeric purity was verified by conversion to optically active [Ru(phen) 3] 2+. Subsequent nucleophilic displacement of both coordinated CH 3CN by X − (where X − = CN −, Cl −, py) proceeds with near complete retention of configuration. The isolation of the optically active neutral species cis-[Ru(phen) 2(CN) 2] and cis-[Ru(phen) 2Cl 2] is significant, since the traditional resolution method via diastereoisomer formation is not directly applicable. Furthermore, cis-[Ru(phen) 2(CN) 2] may serve as a valuable chiral building block for an extensive series of polymetallic complexes where CN − functions as a bridging ligand. The availability of authentic samples of resolved cis-[Ru(phen) 2Cl 2] is important for the quantitative assessment of stereoselectivity in the covalent binding of such racemic complexes with DNA.

Resolution of cis and trans isomers of peptides containing proline using capillary zone electrophoresis

Capillary zone electrophoresis (CZE) is known for its high separation efficiency. Optically gated CZE is a form of CZE that allows rapid analyses while high separation efficiency is maintained. Analysis of peptides containing proline with CZE and optically gated CZE gives two peaks for dipeptides and multiple peaks for oligopeptides containing more than one proline. The multiple peaks are believed to be due to the cis and trans forms possible in peptide bonds containing proline. Isomerization between the cis and trans forms takes place at room temperature with a lifetime of seconds to minutes. Resolution of these peaks in CZE is found to be a function of separation efficiency and time of analysis. Rapid analyses with relatively lower separation efficiency give resolution equal to or better than that of longer analyses with much higher efficiency. This confirms the relationship between the multiple peaks and isomerization between the cis and trans forms. To extract kinetic information from the experimental data, a digital simulation is used to model the separation obtained experimentally. The equilibrium constant and rate constants that give the best fit of the simulated data to the experimental data are considered estimates of the actual values for the given experimental conditions.

Identification of some uncommon monounsaturated fatty acids of bacteria.

Location of the double-bond position of monounsaturated fatty acids of various bacteria was accomplished with combined gas chromatography-mass spectrometry analysis of dimethyl disulfide (DMDS) derivatives. The monoenoic fatty acids from whole cells were converted to methyl esters and then to DMDS adducts and analyzed by capillary gas chromatography-mass spectrometry. The mass spectra of DMDS adducts gave an easily recognizable molecular ion and two major diagnostic ions attributable to fragmentation between the two CH3S groups located at the original site of unsaturation. Twenty-one relatively novel monoenoic fatty acids were identified among the bacteria studied. All Flavobacterium species contained i17:1 omega 8c, Bacillus alvei contained i16:1 omega 11c and i17:1 omega 12c, and Psychrobacter immobilis contained 12:1 omega 9c. Resolution of cis and trans isomers with capillary gas chromatography and subsequent mass spectrometry permitted positive identification of 16:1 omega 7c and 16:1 omega 7t in Arcobacter (Campylobacter) cryaerophila and 16:1 omega 9c and 16:1 omega 9t in Aerococcus viridans.

ChemInform Abstract: A Kinetic Resolution of Racemic Epoxides by a Chiral Lithium Amide.

Abstract A kinetic resolution of cis -disubstituted epoxides was effectively achieved by a chiral lithium amide, prepared from ( S )-2-(pyrrolidin-1-yl)-methylpyrrolidine.

Location of double bonds in monounsaturated fatty acids of Campylobacter cryaerophila with dimethyl disulfide derivatives and combined gas chromatography-mass spectrometry.

Location of the double-bond position of monounsaturated fatty acids in Campylobacter cryaerophila was accomplished with combined gas chromatography-mass spectrometry analysis of dimethyl disulfide (DMDS) derivatives. The monoenoic fatty acids from whole bacterial cells were converted to methyl esters and then to DMDS adducts and analyzed by capillary gas chromatography-mass spectrometry. The mass spectra of DMDS adducts gave an easily recognizable molecular ion (M+) and two major diagnostic ions attributable to fragmentation between the two CH3S groups located at the original site of unsaturation. Two previously unidentified acids that distinguish C. cryaerophila from other bacteria were identified as C14:1 omega 7 and C16:1 omega 7 from their mass spectral fragmentation patterns. Resolution of cis and trans isomers by capillary column gas chromatography permitted assignment of the trans isomer to the C16:1 omega 7 acid.

Resolution of cis- and trans-dimethylcyclohexanes by partition gas chromatography through cyclodextrin complexes

α- and β-Cyclodextrins, dissolved in formamide or ethylene glycol, were applied as stationary phases in gas chromatography for the resolution of isomeric cis- and trans-1,2-, 1,3-, and 1,4-dimethylcyclohexanes. It was found that stereoselectivity arising from inclusion of dimethylcyclohexanes in cyclodextrin cavities is more distinct for β-cyclodextrin. Of the two matrix solvents, which influence not only the capacity factors but also the separation factors, formamide is the more efficient medium for stereoselective cyclodextrin inclusion processes. An evaluation of stability constants of (β-cyclodextrin · dimethylcyclohexane) complexes was attempted. Almost complete separation of a mixture containing the six isomers investigated was achieved by using concentrated β-cyclodextrin (1.48 mol. %) in formamide solution.

Rapid analysis of trans fatty acids on SP-2340 glass capillary columns

The application of 15-m glass capillary columns coated with SP-2340 in the analysis of trans fatty acids is demonstrated. Although resolution of cis and trans isomers is incomplete on short columns, appropriate correction factors can be applied which permit the rapid quantitative analysis of fatty acid mixtures containing trans isomers. The conditions employed permit a fairly detailed analysis of fatty acids of tissue samples in less than 30 min and the analysis of fatty acids derived from partially hydrogenated food fats in under 15 min after purification and preparation of the methyl esters.

ChemInform Abstract: THE STEREOSELECTIVITY OF KETONE REDUCTION WITH SPOROTRICHUM EXILE, RESOLUTION OF CIS‐ AND TRANS‐2‐BENZOYLOCTAHYDRO‐6(2H)‐ISOQUINOLONES

Chemischer InformationsdienstVolume 5, Issue 10 Preparative Organic Chemistry ChemInform Abstract: THE STEREOSELECTIVITY OF KETONE REDUCTION WITH SPOROTRICHUM EXILE, RESOLUTION OF CIS- AND TRANS-2-BENZOYLOCTAHYDRO-6(2H)-ISOQUINOLONES M. R. USKOKOVIC, M. R. USKOKOVICSearch for more papers by this authorD. L. PRUESS, D. L. PRUESSSearch for more papers by this authorC. W. DESPREAUX, C. W. DESPREAUXSearch for more papers by this authorS. SHIUEY, S. SHIUEYSearch for more papers by this authorG. PIZZOLATO, G. PIZZOLATOSearch for more papers by this authorJ. GUTZWILLER, J. GUTZWILLERSearch for more papers by this author M. R. USKOKOVIC, M. R. USKOKOVICSearch for more papers by this authorD. L. PRUESS, D. L. PRUESSSearch for more papers by this authorC. W. DESPREAUX, C. W. DESPREAUXSearch for more papers by this authorS. SHIUEY, S. SHIUEYSearch for more papers by this authorG. PIZZOLATO, G. PIZZOLATOSearch for more papers by this authorJ. GUTZWILLER, J. GUTZWILLERSearch for more papers by this author First published: March 12, 1974 https://doi.org/10.1002/chin.197410148AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume5, Issue10March 12, 1974 RelatedInformation

Synthesis and Resolution of cis- and trans-5-Methylproline

Synthesis and Resolution of cis- and trans-5-Methylproline

1,10-Phenanthroline and 2,2′-bipyridyl complexes of rhodium(III)

The preparation of cis-[Rh(aa)2Cl2]+(aa = 2,2′-bipyridyl or 1,10-phenanthroline) has been re-examined and shown to be catalytic. The preparation and characterisation of cis-[Rh(aa)2X2]n+(X = I–, CN–, H2O, and NH3) and cis-[Rh(aa)2ClY]m+(Y = H2O, NH3, pyridine, and NO2–) is described and the possible mechanisms of base hydrolysis and of substitution by cyanide and by iodide into cis-[Rh(aa)2Cl2]+ are discussed; the effect of dioxygen on these substitutions is also discussed. The resolution of cis-[M(aa)2Cl2]+(M = Rh or Ir) into optical isomers is described and their stability is discussed. A convenient catalytic preparation of [Rh(aa)3]3+ is given.

Nuclear magnetic resonance as a monitor in optical resolutions. II. Synthesis and resolution of cis- and trans-2-(o-bromophenyl)cyclohexylamines

Nuclear magnetic resonance as a monitor in optical resolutions. II. Synthesis and resolution of cis- and trans-2-(o-bromophenyl)cyclohexylamines

One-Step Synthesis and Enzymatic Resolution of cis- and trans-3-Hydroxyproline

<b>One-Step Synthesis and Enzymatic Resolution of <b><i>cis</i></b>- and <b><i>trans</i></b>-3-Hydroxyproline</b>

Stereochemistry of Allylic Rearrangements. I. The Synthesis, Assignment of Configuration and Resolution of cis- and trans-5-Methyl-2-cyclohexenol1

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStereochemistry of Allylic Rearrangements. I. The Synthesis, Assignment of Configuration and Resolution of cis- and trans-5-Methyl-2-cyclohexenol1Harlan L. Goering and Jean P. BlanchardCite this: J. Am. Chem. Soc. 1954, 76, 21, 5405–5408Publication Date (Print):November 1, 1954Publication History Published online1 May 2002Published inissue 1 November 1954https://doi.org/10.1021/ja01650a045RIGHTS & PERMISSIONSArticle Views143Altmetric-Citations12LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (577 KB) Get e-Alerts Get e-Alerts

286. The resolution of cis- and trans-dl-3-carboxy-1 : 1-dimethylcyclopropane-2-propionic acids and of trans-dl-caronic acid

286. The resolution of cis- and trans-dl-3-carboxy-1 : 1-dimethylcyclopropane-2-propionic acids and of trans-dl-caronic acid