Lanthanide-induced Shifts Research Articles

Steric origin of isotope effects in nuclear magnetic resonance shifts induced by lanthanide shift reagents; effect of deuteriation of methyl substituted pyridines

Deuteriation of all the methyl groups, or the 2- and 6-methyl groups, in 2,4,6-trimethylpyridine causes a large (ca. 6%) isotope effect on the lanthanide-induced shift for the 3- and 5-hydrogen atoms, whereas the effect of deuteriation of the 4-methyl group is not detectable (<0·2%); a steric origin is proposed for the secondary isotope effect in lanthanide-induced shifts.

Comments on the sensitivity of lanthanide-induced shifts to the metal substrate distance

The agreement between calculated and measured lanthanide induced shifts for the 2:1 pyridine (py), 4-picoline (4-pic) and 3,5-lutidine (3,5-lut) adducts of Eu(thd) 3 at both ambient and low temperatures using the full two-term dipolar shift equation has been examined as a function of LnN distance. It is found that the agreement factor is of limited sensitivity as a function of the LnN distance. These results question the validity of LnS distances determined exclusively using the single term McConnell-Robertson equation for calculating LIS.

Structural analysis by lanthanide shift reagents: IV . Conformation of the amide group as a function of the ring size in lactams

Computer simulation of the lanthanide induced shifts (LIS) has been performed for ten lactams of variable ring size using methods previously described. The results obtained allow the determination of the conformation of the amide group in these lactams, which is found to be cis or trans depending from the ring size. Self-association is present in smaller ring lactams to a sizeable extent and this could interfere with the LIS simulation process. However, experimental evidence was obtained showing that the cyclic dimers formed by small sized lactams do not interact with the LSR.

Calculations of lanthanide-induced shifts from molecular structure. II

Calculations of lanthanide-induced shifts from molecular structure. II

Structure differentiation by means of lanthanide-induced nitrogen-14 chemical shifts

Structure differentiation by means of lanthanide-induced nitrogen-14 chemical shifts

ChemInform Abstract: A SIMPLE METHOD FOR SIMULATING LANTHANIDE INDUCED SHIFTS IN BIFUNCTIONAL SUBSTRATES

Chemischer InformationsdienstVolume 6, Issue 8 Preparative Organic Chemistry ChemInform Abstract: A SIMPLE METHOD FOR SIMULATING LANTHANIDE INDUCED SHIFTS IN BIFUNCTIONAL SUBSTRATES A. RECCA, A. RECCASearch for more papers by this authorP. FINOCCHIARO, P. FINOCCHIAROSearch for more papers by this author A. RECCA, A. RECCASearch for more papers by this authorP. FINOCCHIARO, P. FINOCCHIAROSearch for more papers by this author First published: February 25, 1975 https://doi.org/10.1002/chin.197508149Read the full textAboutPDF 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. Volume6, Issue8February 25, 1975 RelatedInformation

Lanthanide-induced shifts in proton nuclear magnetic resonance spectra. XI. Equilibrium constants and bound shifts for cyclohexanones and cyclohexanols

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLanthanide-induced shifts in proton nuclear magnetic resonance spectra. XI. Equilibrium constants and bound shifts for cyclohexanones and cyclohexanolsM. D. Johnston Jr., B. L. Shapiro, M. J. Shapiro, T. W. Proulx, A. D. Godwin, and H. L. PearceCite this: J. Am. Chem. Soc. 1975, 97, 3, 542–554Publication Date (Print):February 1, 1975Publication History Published online1 May 2002Published inissue 1 February 1975https://doi.org/10.1021/ja00836a014RIGHTS & PERMISSIONSArticle Views114Altmetric-Citations56LEARN 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 (1 MB) Get e-Alerts Get e-Alerts

ChemInform Abstract: DETERMINATION OF CONFORMATIONS OF ESTERS WITH THE USE OF LANTHANIDE SHIFT REAGENTS

Chemischer InformationsdienstVolume 6, Issue 1 Physical Organic Chemistry ChemInform Abstract: DETERMINATION OF CONFORMATIONS OF ESTERS WITH THE USE OF LANTHANIDE SHIFT REAGENTS KAZUHIKO SAKAMOTO, KAZUHIKO SAKAMOTOSearch for more papers by this authorMICHINORI OKI, MICHINORI OKISearch for more papers by this author KAZUHIKO SAKAMOTO, KAZUHIKO SAKAMOTOSearch for more papers by this authorMICHINORI OKI, MICHINORI OKISearch for more papers by this author First published: January 7, 1975 https://doi.org/10.1002/chin.197501077AboutPDF 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. Volume6, Issue1January 7, 1975 RelatedInformation

Assessment of configuration of four isomeric α,β-unsaturated sulfones using a lanthanide shift reagent

This report describes the application of a computer-aided Lanthanide Induced Shift (LIS)-analysis to discriminate between the four isomeric α,β-unsaturated sulfones 1a–d. The effect of rotation around the MeSO 2C and MeSC bonds upon the agreement between experimental and calculated Eu(fod) 3 induced shifts has been investigated.

Conformational Analysis of Mesityloxide (1-Phthalazinyl)hydrazone (DJ-1461) by Lanthanide-induced Shifts

Conformational Analysis of Mesityloxide (1-Phthalazinyl)hydrazone (DJ-1461) by Lanthanide-induced Shifts

Lanthanide-induced shifts in inorganic and organometallic compounds: a method for distinguishing between N- and S-thiocyanato-compounds

Appreciable Lanthanide-induced shifts are ob-served in the 1H n.m.r. spectra of organic thiocynates on addition of tris-(7,7-dimethyl-1,1,1,2,2,3,3-heptafluoro-octane-4,6-dionato)europium(III)[Eu(fod)3], but not in the spectra of isothiocyanates RNCS; a similar distinction in behaviour occurs for inorganic compounds containing S- and N-thiocyanato-groups and suitable proton-containing ligands, and provides a convenient method for distinguishing between possible isomers.

Application of a lanthanide shift reagent, Eu(fod)3 to the elucidation of the structures of flavones and related compounds

Application of the paramagnetic shift reagent Eu(fod)3 in n.m.r. spectral studies of 5,7-dimethoxyflavone derivatives showed that the signals due to H-3, H-6, and H-8 could be distinguished on the basis of lanthanide-induced shifts; the method is thus useful for structural assignments and has been successfully applied to methyl ethers of biflavones, isoflavones, and xanthones. The difference in co-ordination state between Eu(fod)3 and Eu(dpm)3 in the case of 5-methoxychromone derivatives is discussed.

The biosynthesis of fungal metabolites. Part V. Structure of variecoxanthones A, B, and C, metabolites of Aspergillus variecolor; conversion of variecoxanthone A into (±)-de-C-prenylepishamixanthone

Variecoxanthones A, B, and C, metabolites of a variant strain of Aspergillus variecolor are shown to be 8-hydroxy-1-hydroxymethyl-3-methyl-2-(3-methylbut-2-enyloxy)-(IV), 8-hydroxy-1-hydroxymethyl-3-methyl-5-(3-methylbut-2-enyl)-2-(3-methylbut-2-enyloxy)-(V), and 5-(2,3-epoxy-3-methylbutyl)-8-hydroxy-1-hydroxy-methyl-2-(3-methylbut-2-enyloxy)-xanthone (VI), respectively. These structures were established by detailed spectroscopic comparisons with shamixanthone (I) and tajixanthone (II) and by hydrogenolysis of variecoxanthone A to 2,8-dihydroxy-1,3-dimethylxanthone (X). Acid-catalysed cyclisation of the variecoxanthone-A-derived compound, 1-formyl-8-hydroxy-3-methyl-2-(3-methylbut-2-enyloxy)xanthone (XI), gave 1,2-cis-2,3-dihydro-1,11-dihydroxy-2-isopropenyl-5-methylpyrano[3,2-a]xanthen-12(1H)-one (XIII). The cis-relationship of the 1- and 2-substituents in this compound and the corresponding trans-relationship in shamixanthone are confirmed by comparison of 1H couplings in the hydrogenated derivatives (XIV) and (III), respectively with those in the synthetic 1,2-cis- and 1,2-trans-2,3-dihydro-1-hydroxy-2-isopropyl-7-methyl-1H-benzopyrans (XVI) and (XVII), respectively, prepared by reduction of the corresponding chromone (XVIII) with sodium borohydride. The relative stereochemistry of compounds (XVI) and (XVII) was determined by lanthanide-induced shift studies on their respective 13C and 1H n.m.r. spectra. The mechanistic and biogenetic implications of the acid-catalysed cyclisation of compound (XI) are discussed.

Carbon-13 nuclear magnetic resonance spectra of vitamins D and related compounds.

1. The natural abundance carbon-13 nmr of vitamins D (D2 and D3) and several isomers (5, 6-trans-vitamin D2, isotachysterol2 and isovitamin D2) have been completely assigned by employing off-resonance noise-decoupling, acetylation shifts, and lanthanide-induced shifts experiments. The last two techniques were especially useful for the present study. 2. Carbon-13 nmr spectral characteristics of the three main conjugated triene moieties (SE-Z-SZ, SE-E-SZ, or SE-E-SE), involved in the molecules of vitamin D and its isomers, were revealed. Thus, the striking dependence of the shieldings on molecular geometries and high sensitivity of the resonances to the environments of conjugated systems were surveyed. 3. Conformational preferences in solutions of the hydroxyl groups in vitamins D2 and D3 as well as 5, 6-trans-vitamin D2 were conveniently determined.

Stereochemistry of the t-butylcyanoketen cycloaddition to norbornene

The stereochemistry of the title cycloaddition has been determined by lanthanide-induced shift experiments; the cyclobutanone ring is exo, while the t-butyl group is pointing towards the methylene bridge of norbornane.

ChemInform Abstract: STRUCTURAL ANALYSIS BY LANTHANIDE‐INDUCED SHIFTS PART 5, INFLUENCE OF STERIC AND CONJUGATE EFFECTS ON THE BARRIERS TO ROTATION IN N,N‐DIMETHYLAMIDES

Chemischer InformationsdienstVolume 5, Issue 51 Physical Organic Chemistry ChemInform Abstract: STRUCTURAL ANALYSIS BY LANTHANIDE-INDUCED SHIFTS PART 5, INFLUENCE OF STERIC AND CONJUGATE EFFECTS ON THE BARRIERS TO ROTATION IN N,N-DIMETHYLAMIDES G. MONTAUDO, G. MONTAUDOSearch for more papers by this authorP. MARAVIGNA, P. MARAVIGNASearch for more papers by this authorS. CACCAMESE, S. CACCAMESESearch for more papers by this authorV. LIBRANDO, V. LIBRANDOSearch for more papers by this author G. MONTAUDO, G. MONTAUDOSearch for more papers by this authorP. MARAVIGNA, P. MARAVIGNASearch for more papers by this authorS. CACCAMESE, S. CACCAMESESearch for more papers by this authorV. LIBRANDO, V. LIBRANDOSearch for more papers by this author First published: December 24, 1974 https://doi.org/10.1002/chin.197451108Read the full textAboutPDF 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, Issue51December 24, 1974 RelatedInformation

ChemInform Abstract: ANTILEUKEMIC PSEUDOGUAIANOLIDES FROM HYMENOXYS GRANDIFLORA (T. AND G.) PARKER, APPLICATION OF LANTHANIDE‐INDUCED SHIFTS TO STRUCTURE DETERMINATION

Chemischer InformationsdienstVolume 5, Issue 45 Natural Products ChemInform Abstract: ANTILEUKEMIC PSEUDOGUAIANOLIDES FROM HYMENOXYS GRANDIFLORA (T. AND G.) PARKER, APPLICATION OF LANTHANIDE-INDUCED SHIFTS TO STRUCTURE DETERMINATION W. HERZ, W. HERZSearch for more papers by this authorK. AOTA, K. AOTASearch for more papers by this authorA. L. HALL, A. L. HALLSearch for more papers by this authorA. SRINIVASAN, A. SRINIVASANSearch for more papers by this author W. HERZ, W. HERZSearch for more papers by this authorK. AOTA, K. AOTASearch for more papers by this authorA. L. HALL, A. L. HALLSearch for more papers by this authorA. SRINIVASAN, A. SRINIVASANSearch for more papers by this author First published: November 12, 1974 https://doi.org/10.1002/chin.197445428Read the full textAboutPDF 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, Issue45November 12, 1974 RelatedInformation

PMR analysis of alkenoic esters using shift reagents

The use of the deuterated shift reagent, Eu(FOD) 3-d 30, has enabled an identification to be made of the 8- to 12-isomers of methyl trans-octadecenoate from PMR measurements at 100 or 220 MHz. The δ-values observed were in good agreement with those calculated from a method employing the lanthanide-induced shifts (LIS) in methyl stearate and the deshielding effects of the double bond. Use was made of the δ-value of the methyl ester absorption as an internal reference to allow corrections to be made for changes in measuring conditions. It is concluded that all positional isomers of both cis and trans methyl octadecenoates may be identified by this method.

Determination of Conformations of Esters with the Use of Lanthanide Shift Reagents

Abstract Lanthanide shift reagents have been used for diagnosis of s-trans and s-cis conformations of esters. By taking a ratio of lanthanide-induced shift of (H)CH2C=O protons vs. [shift reagent]/[substrate] as a reference, relative ratio of (H)CH2O- of the s-trans form has been found to be almost unity, whereas that of the s-cis ca. 0.5.

ChemInform Abstract: CONFORMATIONAL ANALYSIS BY LANTHANIDE INDUCED SHIFTS, N‐NITROSOPIPERIDINES

Chemischer InformationsdienstVolume 5, Issue 36 Physical Organic Chemistry ChemInform Abstract: CONFORMATIONAL ANALYSIS BY LANTHANIDE INDUCED SHIFTS, N-NITROSOPIPERIDINES T. P. FORREST, T. P. FORRESTSearch for more papers by this authorD. L. HOOPER, D. L. HOOPERSearch for more papers by this authorS. RAY, S. RAYSearch for more papers by this author T. P. FORREST, T. P. FORRESTSearch for more papers by this authorD. L. HOOPER, D. L. HOOPERSearch for more papers by this authorS. RAY, S. RAYSearch for more papers by this author First published: September 10, 1974 https://doi.org/10.1002/chin.197436054AboutPDF 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, Issue36September 10, 1974 RelatedInformation