IR Evidences for N-9 and N-7 Regioisomers of the Acyclic Purine Nucleoside Analogues

The IR spectra have been recorded in the solid state for the parent molecule, 6-(N-pyrrolyl)purine (1) and its N-9-and N-7-substituted derivatives: 9-and 7-(2-hydroxyprop-1-yl)-6-(N-pyrrol-1-yl)purine (2 and 3), 9-and 7-(2-acetoxyprop-1-yl)-6-(N-pyrrol-1-yl)purine (4 and 5), 9-and 7-(2,3-dihydroxyprop-1-yl)-6-(N-pyrrol-1-yl)purine (6 and 7) as well as 9-and 7-(2,3-diacetoxyprop-1-yl)-6-(N-pyrrol-1-yl)purine (8 and 9). Analysis of the characteristic bands has proved to be useful in differentiating between N-9 and N-7 regioisomers.     

Complete Analysis of the 1H and 13C NMR Spectra of 5-Isopropylsulfonyl-2-Norbornenes Through the Application of Two-Dimensional NMR Techniques

Total assignment of ¹³C and ¹H NMR spectra of the 5-isopropylsulfonyl-2-norbornenes 2 was achieved using the concerted application of two-dimensional homonuclear and heteronuclear chemical shift correlations. The stereochemistry of both the diastereoisomers endo 2a and exo 2b have been established using the magnitude of the proton coupling constants.     

1H AND 13C NMR Assignments of Artheethers

The ¹H and ¹³C nmr assignments for all hydrogen and carbon atoms were made for β and α arteethers (5 and 6) based on chemical shift theory and 2D-nmr techniques (COSY and HETCOR).     

Assignments of 1H and 13C NMR Spectral Data for Benzoylecgonine,a Cocaine Metabolite

The complete assignment of the ¹H and ¹³C NMR spectra of benzoylecgonine, a cocaine metabolite, was performed, with the aid of some 2D experiments such as gCOSY and gHSQC.     

Conformational Analysis of Baclofen Analogues by 1H and 13C NMR: Phaclofen,Saclofen, and Hydroxy-Saclofen. Influence of the Anionic Moiety

The conformations of three analogues of baclofen 1: phaclofen, saclofen, and hydroxy-saclofen 2–4, potent GABA_B antagonists, in solution (D₂O) are estimated from high-resolution (300 MHz) H NMR coupling data. Conformations and populations of conformers are calculated by means of a modified Karplus-like relationship for the vicinal coupling constants. H NMR spectral analysis evidences how 1–3 keep in solution the preferred a conformation around C3-C4 bond. A partial rotation is set up around C2–C3 bond (the conformations about C2–C3 are all highly populated in solution) particularly for 2 and 3 while 1 shows a relative preferred a conformation. This evidences the influence of the anionic moiety.     

Two-Dimensional NMR Spectroscopy in Complete Analysis of the 1H and 13C NMR Spectra of the Ionophore A 23187 and its Calcium Salt

The complete assignment of the proton carbon spectra of the A 23187 Ionophore and its calcium salt is presented.     

1H and 13C NMR Determination of 1-Naphtyl-Polymethoxylated Diphenylwiethanes

The complete structural analysis of 1-[(4-methoxyphenyl)-(3,4,5-trimethoxyphe- nyl)methyl]naphtalene 5a and 1-[(2,5-dimethoxyphenyl)-(3,4,5-trimethoxyphenyl) methyljnaphtalene 5b, prepared by alkylation of 1-[chloro-(3,4,5-trimethoxyphenyl) methyl]naphtalene without by-products such as benzofluorene 2, may be accurately determined by ¹H, ¹³C NMR and 2D NMR analysis.     

13C NMR in the Structural Assignment of Fused Furoxans

The chemical shifts and multiplicities of the two bridgehead carbons in the ¹³C NMR spectra of various fused furoxans are snown to provide a general method for assigning structure in these tautomeric systems.     

TRANILAST ^1H^13CNMR谱分析及其结构的鉴定

本文用COSY,CHCOR等二维核磁共振技术对TRANILAST,2[]3-(3.4-二甲基苯基)1-氧代-2-丙烯基]氨基]苯甲到进行了~1H、~(13)C NMR谱数据分析及归属,并结合~(13)C弛豫时间T_1 及变温实验对合成产品进行了结构鉴定.     

1H and 13C NMR Spectra of Alditolyl Derivatives of 3-Hydrazino-5-Methyl[1,2,4]triazino[5,6-b]indole and Their Cyclized Products.

The ¹H and ¹³C NMR spectra of sugar (5-methyl [1, 2, 4]-triazino [5, 6-b] indol-3-yl) hydrazones (1), per-0-acetyl aldehydo sugar 1-acetyl-1-(5-methyl [1, 2, 4] triazino [5, 6-b]-indol-3-yl) hydrazones (2), l- (penta-0-acetyl-pentitol-1-yl)-10-methyl [l, 2, 4] triazolo [3′, 4′:3, 4] [l, 2, 4] triazino [5, 6-b]-indoles (3) have been investigated. The 2 D NMR (H, C COSY) spectrum of 2a has been studied.     

雷公藤精（Wilforgine）的2D NMR研究

用２Ｄ ＮＭＲ（＾１Ｈ－＾１ＨＣＯＳＹ，＾１Ｈ－＾１３Ｃ ＣＯＳＹ，ＴＯＣＳＹ，ＮＯＥＳＹ和ＣＯＬＯＣ）技术研究了从雷公藤中分离到的雷公藤精，对＾１Ｈ和＾１３Ｃ谱进行了归属。     

Structure Elucidation and Assignment of 1H and 13C Spectra of the New Fused Cyclobutane-Naphthofuran Derivative by Two-Dimensional NMR in Different Solvents

One of the major product from the photodimerization of 2-[2-(2-methyl-phenyl)ethenyl)]naphtho[2. 1-b]furan (1) is a new fused cyclobutane-naphthofuran derivative, 6-(2-methylphenyl)-1-[2-(2-methylphenyl)ethenyl]-7-(2-naphtho-[2,1-b]furyl)-3-[2,1]naphtho-2-oxabicyclo[3.2.0]hept-3-ene (2). Its ¹H and ¹³C NMR spectra were fully assigned by the application of COSY, LR COSY, NOESY, APT and HETCOR experiments in deuterated chloroform, acetone and benzene solutions.     

17O and 13C NMR Studies of Isobenzopyrylium Salts

¹³C and ¹⁷O NMR chemical shifts for a series of isobenzopyrylium salts are reported. The oxygen signal range from 300 to 270 ppm as a double bonded carboxylic oxygen, From the ¹⁷O and ¹³C data valuable informations on the conjugative and substituent effects of isobenzopyrylium salts were obtained.     

13C NMR Chemical Shifts of Heterocycles: Empirical Substituent Effects in 5-Halomethylisoxazoles

Evaluation by empirically derived equations for the Substituent effect (α, β, γ, δ) on the ¹³C NMR chemical shifts for C-3, C-4. C-5 and halomethyl-substituent carbon (C-6) in isoxazoles 1-5 [where C-3 substituent (R¹) = H, alkyl or phenyl, C-4 Substituent (R²) = H, alkyl, and C-5 substituent (R³) = di-or trihalomethyl, methyl and H], taking as reference the compound la, is reported. From the calculated values for the α, β, γ, δ effects for each substituent it was possible to estimate the chemical shift of each carbon of the compounds 1–5. The ¹³ C chemical shifts of the C-3, C-4, C-5, C-6 of these compounds, can be estimated with good precision: 94% of the calculated chemical shifts are found to be within ±1.0ppm, and 100% are found to be within ±1.5ppm.     

Convenient Synthesis 1H, 13C NMR Study and X-Ray Crystal Structure Determination of Some New Disubstituted Thiophenes

2,5-, 3,4- and 2,3-Thienylenediacrylic (1, 4 and 7 respectively) were synthesized in one step reaction by catalytic vinylation of the corresponding dibromothiophenes in the presence of cyclohexylamine salt of acrylic acid. 2,4-Thienylenediacrylic acid 10 was prepared by catalytic vinylation of 3-(4-bromo-2-thienyl)acryilic acid.     

1H and 13C NMR Spectral Study of Some 2r-Aryl-6c-phenylthian-4-ones,Their 1-Oxides and 1,1-Dioxides

ABSTRACT

Four 2r-aryl-6c-phenylthian-4-ones 1b?1e and their 1-oxides 2b?2e and 1,1-dioxides 3b?3e have been newly synthesized. ¹H and ¹³C NMR spectra have been recorded for all these compounds and 2r,6c-diphenylthian-4-one 1-oxide 2a. ¹³C NMR spectrum has been recorded for the sulfone 3a of 1a. For selected compounds ¹H-¹H COSY, HSQC, HMBC, and NOESY spectra have been recorded. The vicinal proton–proton coupling constants suggest that in all these compounds, the heterocyclic ring adopts chair conformation with equatorial orientations of the aryl and phenyl groups. Proton and carbon chemical shifts suggest that in the sulfoxides, the S=O bond is axial and enhances the J _aa value by some special effect. The S = O bond causes a significant upfield shift even on carbons without hydrogens. Significant solvent shifts also were observed.     

Analysis of 1H and 13C{1H} NMR Spectral Parameters and Geometries of Three Isomeric Diphenylbicyclo[2.2.1]Hept-5-Ene-2,3-Dicarboxylic Anhydrides

Diels-Alder adducts of 1,4-diphenyl-1,3-cyclopentadiene and maleic anhydride were investigated by recording the ¹H and ¹³C{¹H} NMR spectra of three isomeric diphenylbicyclo[2.2.1]hept-5-ene endo and exo 2,3-dianhydrides. the spectra were recorded in CD₂Cl₂ and analysed completely. the effect of the endo and exo configuration of the anhydride ring on the chemical shifts of the bridgehead phenyl protons is discussed. the ortho protons of the exo isomers resonate at higher field than those of the endo isomer, and the resonance pattern of the aromatic protons is narrower in the exo than the endo anhydride. the aromatic regions of the spectra are compared with the same regions of the ¹H NMR spectra of the earlier investigated addition products of 1,4-di-p-tolyl-1,3-cyclopentadiene and 1-phenyl-4-p-tolyl-1,3-cyclopentadiene with maleic anhydride. Chemical shifts of the bridge protons are explained on the basis of X-ray data of the compounds and MacroModel calculations on the minimum energy conformations.     

Two-Dimensional NMR Studies of Triterpenoid Glycosides. II)- 1 H NMR Assignment of Arvensoside A and B,Calenduloside C and D

During the investigation of the glycosidic constitutents of Calendula arvensis L. we isolated the previously reported Arvensoside A, Arvensoside B, Calenduloside C and Calenduloside D. The complete assignment ¹H NMR spectra of these compounds was achieved through the concerted application of 2D-homonuclear chemical shift correlations. Calenduloside C and Calenduloside D were isolated for the first time from the fresh aerial parts of Calendula arvensis L.     

13C NMR Study of the Natural Glycosides Vicine and Convicine

¹³C NMR parameters have been obtained for vicine and convicine in DMSO, D₂O/DMSO and D₂O. Complete assignment of the spectra has been achieved. Interpretation of spin-lattice relaxation rates and heteronu-clear NOES has yielded evidence of intramolecular structuring in the case of vicine and not in that of ronvirine and also of a complex network of solute-solvent interactions.     

Derivative Spectroscopy in Conjunction with Thin Layer Chromatography Applied for Determination of Mixtures of Amino Acids in Baby Food.

The preparative thin layer chromatography using silica gel and solvent systems n. butanol : acetic acid: water (4:1:1 V/V) and 96% ethanol : water (70 : 30 v/v) were used to separate the amino acids mixture into groups that can be eluted and one or two of amino acids can be determined by derivative spectroscopy. This was done for determining histidine in presence of cystine, arginine in presence of lysine and ornithine, tryptophan in presence of tyrosine and phenylalanin, and methionine in presence of aspartic acid. The proposed method is applied for determination of these amino acids in baby food, Neslac, Dialac and Nestogen. The statistical analysis of the results were found to be good and in agreement with the ion exchange chromatographic method.