Complete assignment of the 1H and 13C NMR spectra of cis and trans isonucleoside derivatives of purine with a tetrahydropyran ring

¹H and ¹³C NMR chemical shifts of cis and trans isonucleoside analogues of purine in which the furanose moiety is substituted by a tetrahydropyran ring were completely assigned using one‐ and two‐dimensional NMR experiments that include NOE, DEPT, COSY and HSQC. The significant ¹H and ¹³C NMR signals differentiating between the cis and trans stereoisomers were compared. Copyright © 2010 John Wiley & Sons, Ltd.     

One‐ and two‐dimensional NMR characterization of N‐vinyl‐2‐pyrrolidone/methyl acrylate copolymers

N‐vinyl‐2‐pyrrolidone/methyl acrylate (V/M) copolymers were prepared by free‐radical bulk polymerization using benzoyl peroxide as an initiator. The copolymer composition of these copolymers was calculated from ¹H NMR spectra. The radical reactivity ratios for N‐vinyl‐2‐pyrrolidone (V) and methyl acrylate (M) were r_V = 0.09, r_M = 0.44. These reactivity ratios for the copolymerization of V and M were determined using the Kelen–Tudos and nonlinear least‐squares error‐in‐variable methods. The ¹³C{¹H} and ¹H NMR spectra of these copolymers overlapped and were complex. The complete spectral assignment of the ¹³C and ¹H NMR spectra were done with distortionless enhancement by polarization transfer and two dimensional ¹³C‐¹H heteronuclear single quantum correlation spectroscopic experiments. The two‐dimensional ¹H‐¹H homonuclear total correlation spectroscopic NMR spectrum showed the various bond interactions, thus inferring the possible structure of the copolymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2225–2236, 2002     

One‐ and two‐dimensional NMR characterization of N‐vinyl‐2‐pyrrolidone/methyl acrylate copolymers

N‐vinyl‐2‐pyrrolidone/methyl acrylate (V/M) copolymers were prepared by free‐radical bulk polymerization using benzoyl peroxide as an initiator. The copolymer composition of these copolymers was calculated from ¹H NMR spectra. The radical reactivity ratios for N‐vinyl‐2‐pyrrolidone (V) and methyl acrylate (M) were r_V = 0.09, r_M = 0.44. These reactivity ratios for the copolymerization of V and M were determined using the Kelen–Tudos and nonlinear least‐squares error‐in‐variable methods. The ¹³C{¹H} and ¹H NMR spectra of these copolymers overlapped and were complex. The complete spectral assignment of the ¹³C and ¹H NMR spectra were done with distortionless enhancement by polarization transfer and two dimensional ¹³C‐¹H heteronuclear single quantum correlation spectroscopic experiments. The two‐dimensional ¹H‐¹H homonuclear total correlation spectroscopic NMR spectrum showed the various bond interactions, thus inferring the possible structure of the copolymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2225–2236, 2002     

NMR analysis of mono‐ and difructosyllactosucrose synthesized by 1F‐fructosyltransferase purified from roots of asparagus (Asparagus officinalis L.)

Two novel oligosaccharides, mono‐ and difructosyllactosucrose {[O‐β‐D ‐fructofuranosyl‐(2 → 1)]_n‐β‐D ‐fructofuranosyl‐O‐[β‐D ‐galactopyranosyl‐(1 → 4)]‐α‐D ‐glucopyranoside, n = 1 and 2} were synthesized using 1^F‐fructosyltransferase purified form roots of asparagus (Asparagus officinalis L.). Their ¹H and ¹³C NMR spectra were assigned using several NMR techniques. The spectral analysis was started from two anomeric methines of aldose units, galactose and glucose, since they showed separate characteristic signals in their ¹H and ¹³C NMR spectra. After assignments of all the ¹H and ¹³C signals of two units of aldose, they were discriminated as galactose and glucose using proton–proton coupling constants. The HMBC spectrum revealed the galactose residue attached to C‐4 of glucose, fructose residue attached to the C‐1 of glucose, and further fructosyl fructose linkage extended from the glucosyl fructose residues. Copyright © 2002 John Wiley & Sons, Ltd.     

Disentangling Complex Mixtures of Compounds with Near‐Identical 1H and 13C NMR Spectra using Pure Shift NMR Spectroscopy

The thorough analysis of highly complex NMR spectra using pure shift NMR experiments is described. The enhanced spectral resolution obtained from modern 2D HOBS experiments incorporating spectral aliasing in the ¹³C indirect dimension enables the distinction of similar compounds exhibiting near‐identical ¹H and ¹³C NMR spectra. It is shown that a complete set of extremely small Δδ(¹H) and Δδ(¹³C) values, even below the natural line width (1 and 5 ppb, respectively), can be simultaneously determined and assigned.     

[4+2]-Cyclodimer of sabinone: formation,crystal structure,and NMR spectra

Oxidation of (+)-sabinol, (1S,3R,5S)-1-isopropyl-4-methylidenebicyclo[3.1.0]hexan-3-ol, by active MnO₂ afforded not the expected sabinone but only its [4+2]-cyclodimer. The molecular structure of the latter was established by X-ray diffraction analysis. The ¹H and ¹³C NMR spectra of this cyclodimer were interpreted using 2D NMR spectroscopy.     

Stereochemicai study of 7-aryl-1,7,8,8a-tetrahydro-3(2H)indolizinones by1H and13C NMR

Stereochemistry of 7-aryl-1,7,8,8a-tetrahydro-3(2H)-indolizinones was studied by¹H and¹³C NMR. Complete assignment of¹H NMR signals and analysis of¹H-¹H coupling constants were performed using the iterative PANIC program. Values of³ J _6,7,³ J _7,8endo, and⁴ J _5,7 allow one to unambiguously identify the correspondingexo- andendo-stereoisomers. For stereoisomers with exo-orientation of H(7), complete assignment of¹³C NMR signals was performed on the basis of analysis of the¹³C-¹H coupling constants using two dimensional heteronuclear shift-correlating spectroscopy.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 591–593, March, 1996.     

Direct polycondensation of carbon dioxide with xylylene glycols: a new method for the synthesis of polycarbonates

This communication describes the direct polycondensation of carbon dioxide with p- and m-xylylene glycols using the system trisubstituted phosphine/carbon tetrahalide/base as a condensing agent. The polymerization reaction of carbon dioxide with p-xylylene glycol was carried out in the presence of the condensing agent in N,N-dimethylformamide. The yield was at most 81.0% obtained by using the condensing agent tributylphosphine/carbon tetrabromide/N-cyclohexyl-N′,N′,N″,N″-tetramethylguanidine (CyTMG). The structure of the product was determined by means of ¹H NMR, ¹³C NMR, and IR spectroscopy to be that of a polycarbonate. The molecular weight was estimated to be ca. 1 000–2 000 by ¹H NMR analyses.     

P NMR study of the stoichiometry, stability and thermodynamics of complex formation between palladium(II) acetate and bis(diphenylphosphino)ferrocene

The complexation reaction between palladium (II) acetate, and 1,1′-bis(diphenylphosphino)ferrocene, DPPF, was investigated in two different deuterated solvents CDCl₃ and DMSO at various temperatures using ³¹P NMR spectroscopy. The exchange between free and complexed DPPF is slow on the NMR time scale and consequently, two ³¹P NMR signals were observed. At metal ion-to-ligand mole ratio larger than 1, only one ³¹P NMR signal was observed, indicating the formation of a 1:1 Pd²⁺–DPPF complex in solution. The formation constant of the resulting 1:1 complexes was determined from the integration of two ³¹P signals. The values of the thermodynamic parameters (ΔH, ΔS and ΔG₂₉₈) for complexation were determined from the temperature dependence of stability constants. It was found that, in both solvents, the resulting complex is mainly entirely enthalpy stabilized and the ΔH compensates the TΔS contribution.     

Synthesis of Asymmetric Monomethine Cyanine Dyes with Red‐Shifted Optical Properties

Six novel asymmetrical monomethine cyanine dyes were synthesized via the condensation reaction of 1‐butyl‐2‐(methylthio)benzo[c,d]indol‐1‐ium iodide and various 1,5‐substituted indolenine salts under basic conditions. The dyes were characterized using UV–vis spectroscopy, fluorescence, ¹H NMR, ¹³C NMR, and mass spectrometry; furthermore, the purity of these compounds was observed using LC/ELSD/MS.     

α-酮酯和α-酮酰胺的Henry反应

用三乙胺催化环状α-酮酯和α-酮酰胺同硝基甲烷的Henry反应, 首次合成了12个多官能团的β-硝基醇, 它们的结构用元素分析、红外光谱和核磁共振进行了表征. 这一反应速度较快, 室温下进行, 条件温和, 产率较好, 是合成多官能团硝基醇的有效方法.     

Adamantyl-Substituted Amino Alcohols. Synthesis and Functionalization at the Nitrogen and Oxygen Nucleophilic Centers

1-Aminoadamantanes and 1-aminomethyladamantanes were brought into reactions with p-nitro- phenyloxirane and 9-carbazolylmethyloxirane. The reactions occurred in a regioselective fashion according to the Krasusky rule, which was confirmed by the ¹H and ¹³C NMR data. The resulting amino alcohols having a p-nitrophenyl moiety were subjected to functionalization at the nitrogen and oxygen nucleophilic centers using p-nitrobenzenesulfonyl chloride, p-nitrobenzoyl chloride, and hexamethyldisilazane, and N,O-bisacyl derivative was synthesized. The structure of the products was proved by IR and ¹H NMR spectroscopy.     

A new stereoisomer of stemmadenine alkaloid from Tabernaemontana heyneana

A new alkaloid, 15‐β‐stemmadenine, was isolated from the fruits of Tabernaemontana heyneana Wall. from the ethanolic extract. The complete ¹H and ¹³C NMR assignments of the compound were carried out using COSY, HMQC and HMBC. Stereochemistry at C‐15 and C‐16 was established using ROESY and temperature‐dependent ¹H NMR studies. Copyright © 2002 John Wiley & Sons, Ltd.     

New Oenotheralanosterol A and B Constituents from the Oenothera biennis Roots

Two new compounds oenotheralanosterol A and B along with four known compounds have been isolated from the roots of Oenothera biennis. Their structures have been elucidated with the help of 300 MHz NMR using 1D and 2D spectral methods viz: ¹H and ¹³C NMR, ¹H‐¹H COSY, ¹H‐¹³C HETCOR and DEPT aided by EIMS, ESI Mass and IR spectroscopy.     

Complete 13C and 1H NMR spectral assignments of two isoflavones from the roots of Dalbergia horrida

Two methoxylated isoflavones were isolated form the roots of Dalbergia horrida. These compounds show great promise as pharmaceutical agents. The ¹H and ¹³C NMR spectra of the compounds were completely assigned by using a combination of 2D NMR experiments which included ¹H–¹H COSY, HMQC and HMBC studies. Copyright © 2003 John Wiley & Sons, Ltd.     

Conformational Analysis,Thermal Rearrangement,and EI‐MS Fragmentation Mechanism of (1(10)E,4E,6S,7R)‐Germacradien‐6‐ol by 13C‐Labeling Experiments

An uncharacterized terpene cyclase from Streptomyces pratensis was identified as (+)‐(1(10)E,4E,6S,7R)‐germacradien‐6‐ol synthase. The enzyme product exists as two interconvertible conformers, resulting in complex NMR spectra. For the complete assignment of NMR data, all fifteen (¹³C₁)FPP isotopomers (FPP=farnesyl diphosphate) and (¹³C₁₅)FPP were synthesized and enzymatically converted. The products were analyzed using various NMR techniques, including ¹³C, ¹³C COSY experiments. The (¹³C)FPP isotopomers were also used to investigate the thermal rearrangement and EI fragmentation of the enzyme product.     

1H and 13C NMR Assignments for a 27-Norolean-13-en-3-hydroxy-28-oic Acid Glycoside from Isertiahaenkeana

A nortriterpene glycoside, pyrocincholic acid 3β-O-β-6-deoxy-D-glucopyranoside-28-O-β-D-glucopyranoside, was isolated from the leaves of Isertia haenkeana and its structure established by ¹H and ¹³C NMR spectral studies. The complete ¹H and ¹³C NMR resonance assignments for this triterpene were confirmed by the conventional 1D NMR methods and 2D shift-correlated NMR techniques: DQF COSY, TOCSY, ROESY and HMQC.     

The Preparation of a New Kind of Carbosilane Dendrimer with 4‐(Naphthalen‐1‐yl)phenyl Core‐An Application of Suzuki Coupling Reaction

Using the divergent method, carbosilane dendrimers with p‐bromophenyl core were synthesized by using alternating Grignard and hydrosilylation reactions. And then, α‐naphthalenyl was connected to the core by using Suzuki coupling reaction. This gave a new carbosilane dendrimer with a 4‐(naphthalen‐1‐yl)phenyl core. All the products were characterized by IR, ¹H NMR, ¹³C NMR, ²⁹Si NMR, and MS. The study shows that Suzuki Coupling reaction is an effective and powerful core‐functionalization method and a satisfactory result can be achieved through prolonging the reaction time.     

Complete 1H, 13C, 19F and 31P NMR data assignment of CWC‐related chemicals N,N‐dialkyl‐P‐alkyl phosphonamidic fluorides

The complete multinuclear ¹H, ¹³C, ³¹P and ¹⁹F NMR data of symmetrically substituted amines containing N,N‐dialkyl‐P‐alkyl phosphonamidic fluorides are presented. Assignment was achieved, using various one‐and two‐dimensional NMR experiments. Copyright © 2010 John Wiley & Sons, Ltd.     

Phosphorylation and Thiophosphorylation of 2-Substituted Benzoxazoles and Their Biological Activities

Novel organophosphorus compounds have been conveniently prepared using 2-(2′-hydroxynapthyl)benzoxazole and 2-(2′-aminophenyl)benzoxazole as starting materials. Phosphorylation and thiophosphorylation was performed using different molar ratio (1:1, 1:2 and 1:3) of phosphorus oxychloride/thiophosphoryl chloride and substituted benzoxazole. The toxicity of newly synthesized phosphorylated/thiophosphorylated compounds was tested on Aspergillus niger and Fusarium oxysporium. All were found antifungal agents. Plausible structures have been proposed on the basis of IR, ¹ H NMR, ³¹ P NMR spectral studies.