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1.
《Magnetic resonance in chemistry : MRC》2003,41(8):636-638
Complete assignments of 1H and 13C NMR chemical shifts for oleanolic acid, 18α‐oleanolic acid, ursolic acid and their 11‐oxo derivatives based on 1H, 13C, 2D DQF‐COSY, NOESY, HSQC, HMBC and HSQC‐TOCSY experiments were achieved. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
2.
《Magnetic resonance in chemistry : MRC》2003,41(2):143-144
The structure and 13C NMR assignments of 3α‐hydroxyolean‐12‐en‐30‐oic acid (20‐epi‐katonic acid), a novel pentacyclic triterpene isolated from the aerial parts of Bocconia arborea (Papaveraceae), are reported. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
3.
Direct Monitoring of γ‐Glutamyl Transpeptidase Activity In Vivo Using a Hyperpolarized 13C‐Labeled Molecular Probe 下载免费PDF全文
Dr. Tatsuya Nishihara Dr. Hikari A. I. Yoshihara Dr. Hiroshi Nonaka Dr. Yoichi Takakusagi Dr. Fuminori Hyodo Prof. Dr. Kazuhiro Ichikawa Emine Can Dr. Jessica A. M. Bastiaansen Dr. Yuhei Takado Prof. Dr. Arnaud Comment Prof. Dr. Shinsuke Sando 《Angewandte Chemie (International ed. in English)》2016,55(36):10626-10629
The γ‐glutamyl transpeptidase (GGT) enzyme plays a central role in glutathione homeostasis. Direct detection of GGT activity could provide critical information for the diagnosis of several pathologies. We propose a new molecular probe, γ‐Glu‐[1‐13C]Gly, for monitoring GGT activity in vivo by hyperpolarized (HP) 13C magnetic resonance (MR). The properties of γ‐Glu‐[1‐13C]Gly are suitable for in vivo HP 13C metabolic analysis since the chemical shift between γ‐Glu‐[1‐13C]Gly and its metabolic product, [1‐13C]Gly, is large (4.3 ppm) and the T1 of both compounds is relatively long (30 s and 45 s, respectively, in H2O at 9.4 T). We also demonstrate that γ‐Glu‐[1‐13C]Gly is highly sensitive to in vivo modulation of GGT activity induced by the inhibitor acivicin. 相似文献
4.
Lophenol, cholest-4α-methyl-7-en-3β-ol (1), obtained from Dracaena cochinchinensis (Lour.) S. C. Chen, was structurally modified. It was acetylated to protect 3β-hydroxyl group, and then oxidised by selenium dioxide in acetic acid to give cholest-4a-methyl-8-en-3β, Ta-diol diacetate (3). This compound 3 is unstable in chloroform solution or when heated and easily converted to a diene compound, cholest-4a-methyl-7,14-dien-3β-ol acetate (4). The structures of 3 and 4 were elucidated by means of IR, ^1H NMR, ^13C NMR and MS, and the absolute configuration of 3 was established by X-ray crystallography. The property of 3 was also discussed in this paper. Both 3 and 4 are new compounds and were reported for the first time. 相似文献
5.
Linear Free‐Energy Relationships Applied to the 13C NMR Chemical Shifts in 4‐Substituted N‐[1‐(Pyridine‐3‐ and ‐4‐yl)ethylidene]anilines 下载免费PDF全文
Milica Rančić Nemanja Trišović Miloš Milčić Maja Jovanović Bratislav Jovanović Aleksandar Marinković 《Journal of heterocyclic chemistry》2014,51(5):1442-1451
Two series of 4‐substituted N‐[1‐(pyridine‐3‐ and ‐4‐yl)ethylidene]anilines have been synthesized using different methods of conventional and microwave‐assisted synthesis, and linear free‐energy relationships have been applied to the 13C NMR chemical shifts of the carbon atoms of interest. The substituent‐induced chemical shifts have been analyzed using single substituent parameter and dual substituent parameter methods. The presented correlations describe satisfactorily the field and resonance substituent effects having similar contributions for C1 and the azomethine carbon, with exception of the carbon atom in para position to the substituent X. In both series, negative ρ values have been found for C1′ atom (reverse substituent effect). Quantum chemical calculations of the optimized geometries at MP2/6‐31G++(d,p) level, together with 13C NMR chemical shifts, give a better insight into the influence of the molecular conformation on the transmission of electronic substituent effects. The comparison of correlation results for different series of imines with phenyl, 4‐nitrophenyl, 2‐pyridyl, 3‐pyridyl, 4‐pyridyl group attached at the azomethine carbon with the results for 4‐substituted N‐[1‐(pyridine‐3‐ and ‐4‐yl)ethylidene]anilines for the same substituent set (X) indicates that a combination of the influences of electronic effects of the substituent X and the π1‐unit can be described as a sensitive balance of different resonance structures. 相似文献
6.
Chad E. Hadden Gary E. Martin J.‐K. Luo Raymond N. Castle 《Journal of heterocyclic chemistry》2000,37(4):821-825
The assignment of the NMR spectra of the polynuclear heteroaromatic naphtho[2′,1′:5,6]naphtho‐[2′,1′:4,5]thieno[2,3‐c]quinoline is reported. The analysis was based on the homonuclear ROESY, heteronuclear direct GHSQC, IDR‐GHSQC‐TOCSY, and long‐range GHMBC experiments. The complete 1H and 13C shift assignments are reported. 相似文献
7.
Nury Pérez‐Hernández Celina Álvarez‐Cisneros Carlos M. Cerda‐García‐Rojas Martha S. Morales‐Ríos Pedro Joseph‐Nathan 《Magnetic resonance in chemistry : MRC》2013,51(3):136-142
1,2,3,4,6‐Penta‐O‐acetyl‐α‐d ‐glucopyranose and the corresponding [1‐2H], [2‐2H], [3‐2H], [4‐2H], [5‐2H], and [6,6‐2H2]‐labeled compounds were prepared for measuring deuterium/hydrogen‐induced effects on 13C chemical shift nΔ (DHIECS) values. A conformational analysis of the nondeuterated compound was achieved using density functional theory (DFT) molecular models that allowed calculation of several structural properties as well as Boltzmann‐averaged 13C NMR chemical shifts by using the gauge‐including atomic orbital method. It was found that the DFT‐calculated C–H bond lengths correlate with 1Δ DHIECS. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
8.
《Magnetic resonance in chemistry : MRC》2003,41(9):735-738
Extensive 1D (1H NMR, HBBD‐13C NMR, DEPT‐13C NMR) and 2D (COSY, TOCSY, NOESY, HMQC and HMBC) NMR analysis was used to characterize the structure of a new bisdesmoside saponin isolated from the methanol extract of stems of Cordia piauhiensis Fresen as 3β‐O‐[α‐L ‐rhamnopyranosyl‐(1 → 2)‐β‐D ‐glucopyranosyl]ursolic acid 28‐O‐[β‐D ‐glucopyranosyl‐(1 → 6)‐β‐D ‐glucopyranosyl] ester. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
9.
Novel 2,4,5‐Trisubstituted Pyridines as Key Intermediates for the Preparation of the TSPO Ligand 6‐F‐PBR28: Synthesis and Full 1H and 13C NMR Characterization 下载免费PDF全文
Annelaure Damont Frédéric Lemée Guillaume Raggiri Frédéric Dollé 《Journal of heterocyclic chemistry》2014,51(2):404-410
As part of our ongoing research for molecular structures binding to the translocator protein (TSPO 18 kDa), we investigated the preparation of a number of new 2,4,5‐trisubstituted pyridines as novel building blocks. In particular, 5‐amino‐2‐halo‐4‐phenoxypyridines ( 11 , 12 , 13 ) were designed as key intermediates for the synthesis of the recently developed TSPO ligand 6‐F‐PBR28 and its fluorine‐18‐labeled version for positron emission tomography, 6‐[18F]F‐PBR28. We hereby report the chemical preparation as well as the 1H and 13C NMR spectroscopic data of polysubstituted pyridines 2 , 3 , 4 , 5 , 6 , 7 , 7b , 8 , 9 , 10 , 11 , 12 , 13 , 14 . The latter demonstrates dramatic changes in electron density repartition of the aromatic ring upon substitution. 相似文献
10.
Mika Tiainen Hannu Maaheimo Pasi Soininen Reino Laatikainen 《Magnetic resonance in chemistry : MRC》2010,48(2):117-122
The one‐ and two‐bond 13C isotope shifts, typically ?1.5 to ?2.5 ppb and ?0.7 ppb respectively, in non‐cyclic aliphatic systems and up to ?4.4 ppb and ?1.0 ppb in glucose cause effects that need to be taken into account in the adaptive NMR spectral library‐based quantification of the isotopomer mixtures. In this work, NMR spectral analyses of some 13C‐labelled amino acids, D ‐glucose and other small compounds were performed in order to obtain rules for prediction of the 13C isotope effects on 1H chemical shifts. It is proposed that using the additivity rules, the isotope effects can be predicted with a sufficient accuracy for amino acid isotopomer applications. For glucose the effects were found strongly non‐additive. The complete spectral analysis of fully 13C‐labelled D ‐glucose made it also possible to assign the exocyclic proton signals of the glucose. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
11.
Valerie Huemer Gernot A. Eller Wolfgang Holzer 《Magnetic resonance in chemistry : MRC》2010,48(6):476-482
Various [5,6]pyrano[2,3‐c]pyrazol‐4(1H)‐thiones were synthesized in high yields by treatment of the corresponding [5,6]pyrano[2,3‐c]pyrazol‐4(1H)‐ones with Lawesson's reagent. Detailed NMR spectroscopic studies were undertaken of the title compounds. Complete and unambiguous assignment of chemical shifts (1H, 13C, 15N) and coupling constants (1H,1H; 13C,1H) was achieved by the combined application of various one‐ and two‐dimensional (1D and 2D) NMR spectroscopic techniques. Unequivocal mapping of most 13C,1H spin coupling constants is accomplished by 2D (δ, J) long‐range INEPT spectra with selective excitation. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
12.
《Magnetic resonance in chemistry : MRC》2003,41(4):260-264
Complete 1H and 13C resonance assignments were carried out for a new type of carboxyl‐linked glucosides of chenodeoxycholic (3α,7α‐dihydroxy‐5β‐cholan‐24‐oic) and hyodeoxycholic (3α,6α‐dihydroxy‐5β‐cholan‐24‐oic) acids by using several homonuclear (1H–1H) and heteronuclear (1H–13C) 2D NMR techniques. Differences in the 1H and 13C resonances between the α‐ and β‐anomers of the ester glucosides of bile acids were clarified for the first time. A comparison of the 1H and 13C signal shifts induced by β‐D ‐glucosidation at the 24‐carboxyl and 3α‐hydroxyl groups in the parent 5β‐cholanoic acid was also made. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
13.
Rubén Montalvo‐González Armando Ariza‐Castolo 《Magnetic resonance in chemistry : MRC》2012,50(1):33-39
A structural and conformational analysis of 1‐oxaspiro[2.5]octane and 1‐oxa‐2‐azaspiro[2.5]octane derivatives was performed using 1H, 13 C, and 15 N NMR spectroscopy. The relative configuration and preferred conformations were determined by analyzing the homonuclear coupling constants and chemical shifts of the protons and carbon atoms in the aliphatic rings. These parameters directly reflected the steric and electronic effects of the substituent bonded to the aliphatic six‐membered ring or to C3 or N2. The parameters also were sensitive to the anisotropic positions of these atoms in the three‐atom ring. The preferred orientation of the exocyclic substituents directed the oxidative attack. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
14.
《Magnetic resonance in chemistry : MRC》2003,41(12):975-982
The reaction of 2,4‐pentanedione ( 1 ) with (R)‐(—)‐2‐phenylglycine methyl ester ( 2 ), (R)‐(—)‐2‐phenylglycinol ( 3 ) and the proteinogenic amino acids (2S,3R)‐(—)‐2‐amino‐3‐hydroxybutyric acid (L ‐threonine) ( 4 ) and (R)‐(—)‐2‐amino‐3‐mercaptopropionic acid (L ‐cysteine) ( 5 ) methyl esters was investigated. The corresponding enamines 6 , 7 and 8 were isolated and characterized spectroscopically whereas 9 , which is unstable, was transformed in situ into 13 . Treatment of 7 , 8 and 9 with boron trifluoride etherate afforded the new [1,4]oxazepines 10 , 11 and [1,4]thiazepine ( 12 ) as their BF3O? salts. The structures of the enamines and their corresponding seven‐membered heterocycles were assessed by 1D and 2D NMR spectroscopy. Variable‐temperature experiments revealed different molecular mobility behavior among these heterocycles. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
15.
Bernd Wrackmeyer Prof. Dr. Zureima García Hernández Julian Lang Oleg L. Tok 《无机化学与普通化学杂志》2009,635(8):1087-1093
The origin of broadening of 13C(carborane) NMR signals of 1,2‐, 1,7‐ and 1,12‐dicarba‐closo‐dodecaboranes(12) and several diphenylsilyl derivatives has been examined in detail and could be traced only partially to unresolved 13C–11B spin‐spin coupling. Other contributions to the line widths arise from 13C–1H dipole‐dipole interactions and, in particular, from isotope‐induced chemical shifts 1Δ10/11B(13C), observed here for carboranes for the first time. In the case of 1‐diphenylsilyl‐1,2‐dicarba‐closo‐dodecaborane(12), the coupling constant 1J(13C,13C) = 9.3 Hz was measured in natural abundance of 13C. The small value of this coupling constant and its negative sign is predicted by calculations based on optimised structures [B3LYP/6‐311+G(d,p) level of theory] of the parent carboranes and 1‐silyl‐1,2‐dicarba‐closo‐dodecaborane(12) as a model compound [calcd. 1J(13C,13C) = –10.5 Hz]. Calculated coupling constants 1J(13C,11B) are small (<7 Hz), in contrast to published assumptions, and of either sign, whereas 1J(11B,11B) are all positive and range up to 15 Hz. 相似文献
16.
《Magnetic resonance in chemistry : MRC》2002,40(7):477-479
We report the 1H NMR and 13C NMR chemical shifts and J(H,H), J(H,F) and J(C,F) coupling constants of 13 2,4‐diamino‐10‐methylpyrimido[4,5‐b]‐5‐quinolone derivatives, some of them with moderate activity against Plasmodium falciparum in vitro. They were characterized and assigned on the basis of 1H, 13C and 13C–1H (short‐ and long‐range) correlated spectra. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
17.
Yilmaz Yildirir Özgür Pamir Serkan Yavuz Ali Dişli 《Journal of heterocyclic chemistry》2013,50(Z1):E93-E99
In this study, we report the synthesis a series of novel 2‐[N‐(1H‐tetrazol‐5‐yl)‐6,14‐endo‐etheno‐6,7,8,14‐tetrahydrothebaine‐7α‐yl]‐5‐phenyl‐1,3,4‐oxadiazole derivatives ( 7a – e ) which have potential opioid antagonist and agonist. The substitution reaction of 6,14‐endo‐ethenotetrahydrothebaine‐7α‐carbohydrazide with corresponding benzoyl chlorides gave diacylhydrazine compounds 4a – e in good yields. The treatment of compounds 4a – e with POCl3 caused the conversion of side‐chain of compounds 5a – e into 1,3,4‐oxadiazole ring at C(7) position; thus, compounds 5a – e were obtained. Subsequently, cyanamides ( 6a – e ) were prepared from compounds 5a – e and then compounds 7a – e were synthesized by the azidation of 6a – e with NaN3. The structures of the compounds were established on the basis of their IR, 1H NMR, 13C APT, 2D‐NMR (COSY, NOESY, HMQC, HMBC) and high‐resolution mass spectral data. 相似文献
18.
Felix Nußbaumer Raphael Plangger Manuel Roeck Christoph Kreutz 《Angewandte Chemie (International ed. in English)》2020,59(39):17062-17069
We present the access to [5‐19F, 5‐13C]‐uridine and ‐cytidine phosphoramidites for the production of site‐specifically modified RNAs up to 65 nucleotides (nts). The amidites were used to introduce [5‐19F, 5‐13C]‐pyrimidine labels into five RNAs—the 30 nt human immunodeficiency virus trans activation response (HIV TAR) 2 RNA, the 61 nt human hepatitis B virus ? (hHBV ?) RNA, the 49 nt SAM VI riboswitch aptamer domain from B. angulatum, the 29 nt apical stem loop of the pre‐microRNA (miRNA) 21 and the 59 nt full length pre‐miRNA 21. The main stimulus to introduce the aromatic 19F–13C‐spin topology into RNA comes from a work of Boeszoermenyi et al., in which the dipole‐dipole interaction and the chemical shift anisotropy relaxation mechanisms cancel each other leading to advantageous TROSY properties shown for aromatic protein sidechains. This aromatic 13C–19F labeling scheme is now transferred to RNA. We provide a protocol for the resonance assignment by solid phase synthesis based on diluted [5‐19F, 5‐13C]/[5‐19F] pyrimidine labeling. For the 61 nt hHBV ? we find a beneficial 19F–13C TROSY enhancement, which should be even more pronounced in larger RNAs and will facilitate the NMR studies of larger RNAs. The [19F, 13C]‐labeling of the SAM VI aptamer domain and the pre‐miRNA 21 further opens the possibility to use the biorthogonal stable isotope reporter nuclei in in vivo NMR to observe ligand binding and microRNA processing in a biological relevant setting. 相似文献
19.
Sarah El Habnouni Sébastien Blanquer Vincent Darcos Jean Coudane 《Journal of polymer science. Part A, Polymer chemistry》2009,47(22):6104-6115
A novel method is proposed to access to new poly(α‐amino‐ε‐caprolactone‐co‐ε‐caprolactone) using poly(α‐iodo‐ε‐caprolactone‐co‐ε‐caprolactone) as polymeric substrate. First, ring‐opening (co)polymerizations of α‐iodo‐ε‐caprolactone (αIεCL) with ε‐caprolactone (εCL) are performed using tin 2‐ethylhexanoate (Sn(Oct)2) as catalyst. (Co)polymers are fully characterized by 1H NMR, 13C NMR, FTIR, SEC, DSC, and TGA. Then, these iodinated polyesters are used as polymeric substrates to access to poly(α‐amino‐ε‐caprolactone‐co‐ε‐caprolactone) by two different strategies. The first one is the reaction of poly(αIεCL‐co‐εCL) with ammonia, the second one is the reduction of poly(αN3εCL‐co‐εCL) by hydrogenolysis. This poly(α‐amino‐ε‐caprolactone‐co‐ε‐caprolactone) (FαNH2εCL < 0.1) opens the way to new cationic and water‐soluble PCL‐based degradable polyesters. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6104–6115, 2009 相似文献
20.
Toshiaki Taira Yuji Suzaki Dr. Kohtaro Osakada Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(22):6518-6529
Mixtures of N‐alkyl pyridinium compounds [py‐N‐(CH2)nOC6H3‐3,5‐(OMe)2]+(X?) ( 1b Cl: n=10, X=Cl; 1c Br: n=12, X=Br) and α‐cyclodextrin (α‐CD) form supramolecular hydrogels in aqueous media. The concentrations of the two components influences the sol–gel transition temperature, which ranges from 7 to 67 °C. Washing the hydrogel with acetone or evaporation of water left the xerogel, and 13C CP/MAS NMR measurements, powder X‐ray diffraction (XRD), and scanning electron microscopy (SEM) revealed that the xerogel of 1b Cl (or 1c Br) and α‐CD was composed of pseudorotaxanes with high crystallinity. 13C{1H} and 1H NMR spectra of the gel revealed the detailed composition of the components. The gel from 1b Cl and α‐CD contains the corresponding [2]‐ and [3]pseudorotaxanes, [ 1b? (α‐CD)]Br and [ 1b? (α‐CD)2]Br, while that from 1c Br and α‐CD consists mainly of [3]pseudorotaxane [ 1c? (α‐CD)2]Br. 2D ROESY 1H NMR measurements suggested intermolecular contact of 3,5‐dimethoxyphenyl and pyridyl end groups of the axle component. The presence of the [3]pseudorotaxane is indispensable for gel formation. Thus, intermolecular interaction between the end groups of the axle component and that between α‐CDs of the [3]pseudorotaxane contribute to formation of the network. The supramolecular gels were transformed into sols by adding denaturing agents such as urea, C6H3‐1,3,5‐(OH)3, and [py‐N‐nBu]+(Cl?). 相似文献