Carbon-13 NMR spectra of fusicoccin and its derivatives

The ¹³C NMR spectra of fusicoccin, some of its cometabolites and derivatives were studied. Using standard Fourier transform techniques, T₁ relaxation time measurements and lanthanide shift reagents, the resonances of individual carbon-13 nuclei were assigned.     

Spectroscopic data processing. NMRI software and its applications in chemistry and biophysics

The NMRI software system (previously known as ORACLE) is a large modular FORTRAN 77 program for reduction of spectroscopic data from Fourier transform NMR experiments, although the program is applicable to other types of spectroscopy. NMRI features include: (1) implementation of powerful algorithms for optimization of data content; (2) routines for high accuracy quantitation of spectral features, including quantitative separation of over-lapping lines; (3) versatile output routines including color graphics and multi-format hard copy; (4) extensive user prompting and automation control.NMRI is being used in a variety of chemical and biological applications. Examples include quantitation of metabolic NMR spectra, analysis of ¹³C NMR of double stranded DNA, and quantitative analysis of mixtures of organic compounds.     

Structure elucidation and NMR assignments for three anthraquinone derivatives from the marine fungus Fusarium sp. (No. ZH‐210)

The structure elucidations and complete ¹H and ¹³C NMR assignments are reported for three new anthraquinone derivatives: Fusaquinon A (1), B (2), and C (3) isolated from the fermentation medium of the marine fungus Fusarium sp. (No. ZH‐210). HREIMS, Fourier transform infrared absorption spectrometry (FT‐IR), NMR experiments including gCOSY, gHMQC, gHMBC, and NOESY were used for the determination of the structures and NMR spectral assignments. Preliminary pharmacological test showed that they exhibited low cytotoxic activity towards KB, KBv200, and MCF‐7 cell lines. Copyright © 2009 John Wiley & Sons, Ltd.     

含二氮杂萘酮单元双官能团化合物结构的波谱表征

在成功地合成了11个用于制备聚芳酰胺类聚合物的含二氮杂萘酮单元的双官能团化合物基础上,本实验用核磁共振波谱确定了各化合物的结构。用二维同核位移相关谱(gCOSY)、异核^13C-^1H-键相关谱(gHSQC)和异核^13C-^1H远程相关谱(gHMBC)完成了全部^1H和^13C NMR谱带的归属;首次报道了该系列衍生物的氢和碳原子的化学位移值。对其系列化合物的核磁共振波谱及红外光谱的特征进行了讨论。     

13C NMR spectroscopy of 4,5- and 5,6-double bond isomers of spiro-3-steroidal ketone derivatives : The determination of the structures of steroidal thiazolidines

The thiazolidine isomers obtained upon the reaction of aminoethanethiols with α,β-unsaturated steroidal ketones were found to be double bond positional isomers based on their optical rotations and ¹H and ¹³C NMR spectra. The ¹³C NMR spectra of analogous ketals, hemithioketals and a thioketal of steroidal ketones were also reported, and ¹³C NMR spectroscopy was shown to be a convenient method of assigning the position of the double bond in the double bond isomers for all four of these derivatives. Finally, ¹³C NMR spectroscopy was found to be useful in determining that thiazolidine formation was stereospecific to give only one C-3-isomer.     

Hochauflösungs-13C-NMR-Spektroskopie. I—Analyse der Spektren des 1,2,4- und 1,3,5-Triazins sowie ihrer Methyl- und Phenylderivate

Using the pulse Fourier transform technique, the high resolution carbon-13 NMR spectra of 1,2,4- and 1,3,5-triazine and their methyl derivatives as well as the ¹H noise decoupled spectra of phenyl- and methylphenyl substituted triazines, have been recorded and analysed. The chemical shifts of the polysubstituted 1,2,4-triazines normally show additivity; deviations observed with phenyl derivatives are ascribed to steric effects. The ¹³C? H coupling constants are compared to those of benzene, pyridine, the diazines and disubstituted ethylenes. The strong influence on the coupling constants exerted by number and position of the nitrogen atoms is revealed by the observation that geminal couplings in 1,2,4-triazine are larger than vicinal ones, in contrast to the usual sequence.     

Fingerprints of Phalaenopsis Tissues in Growth and Spike Induction Periods—A Solid‐state 13C NMR Approach

Solid‐state Nuclear Magnetic Resonance (ss‐NMR) ¹³C single‐pulse excitation spectroscopy in combination with the magic‐angle spinning (MAS) technique was applied to a series of Phalaenopsis tissues, including the leaf, sheath, stem, and root, at different growth and spiking periods. Compared with{¹H}/¹³C cross‐polarization MAS spectra, the ¹³C single‐pulse excitation MAS spectra displayed very distinct spectral patterns, recognizable as fingerprints of the tissues studied. ¹Here, we demonstrate that solid‐state ¹³C single‐pulse excitation NMR spectroscopy provides a direct and robust analytical tool for studying the various tissues of Phalaenopsis in different growth and spiking induction periods.     

Barriers to internal rotation in 1,3,5-trineopentylbenzenes: V—conformational studies by carbon-13 magnetic resonance

The temperature dependence of the carbon-13 NMR signals in three completely substituted 1,3,5-trineopentylbenzenes has been studied by the Fourier transform technique. The assignment of all peaks was based on studies of 1,3,5-trineopentylbenzene and some of its mono- and disubstituted derivatives. Nearly all carbon signals showed a splitting into several peaks at low temperature, which gave information about the existing rotamers in the completely substituted compounds. Spectra for one compound were studied in a narrow temperature interval in order to test the reliability of rate constants obtained from ¹³C FT spectra. Good agreement was found between previously reported values obtained from ¹H NMR and those obtained in this investigation.     

Derivatization of valproic acid using ferrocene derivatives: Synthesis,characterization and investigation of optical and electrochemical properties

New ferrocenyl‐based valproic acid (VPA) ester derivatives were designed and synthesized according to the reaction of appropriate haloalkylferrocene derivatives with VPA in the presence of K₂CO₃ and a catalytic amount of 18‐crown‐6 ether. Elemental analyses and Fourier transform infrared, ¹H NMR, ¹³C NMR and mass spectra all well confirmed the predicted molecular structure. This is the first report in which ferrocene has been applied in derivatization of VPA as a chromogenic group. The electrochemical properties of the synthesized compounds were studied using cyclic voltammetry measurements, and energies of the frontier molecular orbitals were determined. In addition, the solubilities of the final compounds were studied in distilled water, phosphate buffer (pH = 7.4) and 0.9% (w/v) NaCl solution.     

Pulse Fourier Transform 13C-NMR Spectroscopy,Principles and Applications

As a result of the development of pulse Fourier transform NMR spectroscopy ¹³C resonance has become accepted as a means of elucidating the structures of organic compounds having the natural ¹³C abundance. Assignment of the signals is facilitated by broad-band and off resonance proton decoupling and by knowledge of longitudinal relaxation times. The pulse Fourier technique, which is more sensitive and faster than conventional NMR spectroscopy because of multi-channel excitation, allows ¹³C measurements within a short time even on dilute samples of high molecular weight compounds without prior enrichment in ¹³C.     

Novel synthesis of polyethylene–poly(dimethylsiloxane) copolymers with a metallocene catalyst

Polyethylene–poly(dimethylsiloxane) copolymers were synthesized in solution from an ethylene monomer and an ω‐vinyl poly(dimethylsiloxane) (PDMS) macromonomer at 363 and 383 K with EtInd₂ZrCl₂/methylaluminoxane as a catalyst. The copolymers obtained were characterized with Fourier transform infrared spectroscopy, ¹H and ¹³C NMR, size exclusion chromatography, and differential scanning calorimetry. The rheological properties of the molten polymers were determined under dynamic shear flow tests at small‐amplitude oscillations, whereas the physical arrangement of the phase domains was analyzed with scanning electron microscopy (SEM)/energy dispersive X‐ray (EDX). The analysis of the catalyst activity and the resulting polymers supported the idea of PDMS blocks or chains grafted to polyethylene. The changes in the rheological behavior and the changes in the Fourier transform infrared and NMR spectra were in agreement with this proposal. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2462–2473, 2004     

13C Fourier transform NMR and partially relaxed Fourier transform NMR relaxation study on the ethanol–manganese(II) system

The paramagnetic contribution to the ¹³C and ¹H nuclear relaxation rates in the ethanol-Mn(II) system has been calculated. Both T₁ and T₂ experiments have been performed by means of Fourier transform and partially relaxed Fourier transform NMR spectroscopy. The correlation times for the dipolar and scalar parts have been discussed and evaluated. Calculations of distances and of hyperfine coupling constants have been carried out.     

Hochauflösungs-13C-NMR-Spektroskopie. II—Die Spektren von (2-Dimethylamino-1-propenyl)triazinen

Using the pulse Fourier transform technique, the undecoupled carbon-13 NMR spectra of the products obtained in the reaction of methyltriazines with 1-(dimethylamino)-1-ethoxyethylene have been recorded and completely assigned. A comparison of the observed ¹³C chemical shifts and ¹³C? H coupling constants with those in the starting triazines and in 2-dimethylamino-2-penten-4-one confirms the (2-dimethylamino-1-propenyl) triazine structure. The data are discussed in terms of steric effects and of the configuration and conformation of the sidechain.     

Synthesis of New Spiro[1,4,2-dioxazole-5,3′-indolin]-2′-one by 1,3-Dipolar Cycloaddition

Novel spiro[1,4,2-dioxazole-5,3′-indolin]-2′-one derivatives were synthesized by 1,3-dipolar cycloaddition reactions of the isatin derivative with aryl nitrile oxide. The cycloadducts were characterized by spectral data including ¹H NMR, ¹³C NMR, infrared, mass spectra, and elementary analysis.     

Synthesis and Characterization of New Chalcone Derivatives from cis-Bicyclo[3.2.0]hept-2-en-6-one

A series of chalcone derivatives (3a–k) were prepared via the reaction of cis-bicyclo[3.2.0]hept-2-en-6-one (1) with the respective arylaldehydes (2a–k) and were then characterized by Fourier transform infrared (FT-IR), ¹H NMR, ¹³C NMR, and elemental analyses.     

A Resin-Supported Formate Catalyst for the Transformative Reduction of Carbon Dioxide with Hydrosilanes

A heterogeneous formate anion catalyst for the transformative reduction of carbon dioxide (CO₂) based on a polystyrene and divinylbenzene copolymer modified with alkylammonium formate was prepared from a widely available anion exchange resin. The catalyst preparation was easy and the characterization was carried out by using elemental analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and solid-state ¹³C cross-polarization/magic-angle spinning nuclear magnetic resonance (¹³C CP/MAS NMR) spectroscopy. The catalyst displayed good catalytic activity for the direct reduction of CO₂ with hydrosilanes, tunably yielding silylformate or methoxysilane products depending on the hydrosilanes used. The catalyst was also active for the reductive insertion of CO₂ into both primary and secondary amines. The catalytic activity of the resin-supported formate can be predicted from the FTIR spectra of the catalyst, probably because of the difference in the ionic interaction strength between the supported alkylammonium cations and formate anions. The ion pair density is thought to influence the catalytic activity, as shown by the elemental and solid-state ¹³C NMR analyses.     

Synthesis, characterization, and polymerization of vinylmelamines

Abstract  

Vinyl functionalized melamine derivatives for cross-linking based on polymerization were synthesized as potential substitutes for harmful formaldehyde in melamine resins. Methylmelamines undergo direct vinylation with acetylene to the corresponding vinylmelamines in more than 95% conversion. Their chemical structures were fully characterized by mass spectrometry, Fourier transform infrared (FTIR) spectroscopy, elementary analysis, ¹H, ¹³C, and 2D correlation nuclear magnetic resonance (NMR) experiments. Linear and cross-linked polymers were prepared by free radical polymerization neat and in solution and characterized by size exclusion chromatography (SEC) and matrix-assisted laser desorption ionization time-of-flight (MALDI-ToF) mass spectrometry.     

CHLOROSULPHONATION OF 2-ANILINO-1,4-NAPHTHOQUINONE AND SYNTHESIS OF NEWER SULPHONYL DERIVATIVES

Synthesis of 2-anilino-1,4-napthoquinone-3-sulphonyl chloride (2) was achieved from the reaction of the title compound with chlorosulphonic acid. The interesting derivative 2 was used as a building block for synthesis of the sulphonyl derivatives 3–24. All these sulphonyl derivatives were characterized by the physical and spectral data (IR, Mass, ¹H- and ¹³C NMR spectra).     

13C NMR spectroscopy of cyclopropane derivatives. 1—monocyclic compounds

The ¹³C NMR data of an appreciable number of cyclopropane derivatives have been collected. Most of the spectra were recorded by ourselvesand some were taken from the Literature. With a view to furthering the useof ¹³C NMR spectroscopy as a diagnostic tool in this field, we havemeasured not only the chemical shifts,δ, but also the coupling constants ¹J(CH). It is shown that both embody valuable structural information.     

Synthesis and characterization of a novel Brönsted acidic dicationic ionic liquid based on piperazine and its application in the one-pot synthesis of various xanthenes under solvent-free conditions

In this paper, an interesting Brönsted acidic dicationic ionic liquid based on piperazine was prepared via two-step synthesis. The structure of the dicationic ionic liquid (DIL) was confirmed with various techniques including Fourier transform infrared spectroscopy (FT-IR), Proton NMR (¹H NMR), Carbon-13 NMR (¹³C NMR), mass spectroscopy (MS), acid–base titration as well as Hammett acidity function. Catalytic activity of this novel Brönsted acidic DIL was examined in the xanthene synthesis. High yield of product, short reaction time, easily recovery and reusing of the catalyst, and the absence of organic solvents are some of the merits of the developed procedure.