Direct, easy, and scalable preparation of (diacetoxyiodo)arenes from arenes using potassium peroxodisulfate as the oxidant

The reaction of arenes with potassium peroxodisulfate, elemental iodine, and acetic acid in the presence of concd sulfuric acid, efficiently generates the corresponding (diacetoxyiodo)arenes in good yields, providing an easy, safe, and effective method for preparing (diacetoxyiodo)arenes from arenes and iodine.     

Total assignment of the (1)H- and (13)C-NMR spectra for TZT-1027 and related compounds

The total assignment of the (1)H- and (13)C-NMR spectra for TZT-1027 was carried out using various NMR methods (1D, 2D NMR). It was found that TZT-1027 exists in two different conformations resulting from the cis-trans isomerization of the amide bond at N-11 and C-12 in DMSO-d(6). The (1)H- and (13)C-NMR spectra of compound 1 and 2 comprised of the partial structure of TZT-1027 were also assigned to be TZT-1027. These assignments showed that compound 1 is in good agreement with TZT-1027 with regard to formation of the conformers.     

(1)H- and (13)C-NMR analysis of a series of 1,2-diaryl-1H-4,5-dihydroimidazoles

An analysis of the (1)H- and (13)C-NMR spectra of a series of 1,2-diaryl-1H-4,5-dihydroimidazoles and comparisons with 4,5-dihydroimidazoles having different substitution patterns are presented. The influence of different 1-aryl and 2-aryl group substituents on spectroscopic parameters of the heterocyclic ring and on the contributions of possible mesomeric structures in the system was determined. Spectroscopic features are coherent with the presence of two conjugated systems (Ar(1)-N and Ar(2)-C=N) which compete with the delocalization characteristics of the amidine system.     

Stereochemistry in cationic polymerization of alkenyl ethers. I. 1H- and 13C-NMR spectra of poly(propenyl ethers)

Benzyl, ethyl, and deuterated ethyl propenyl ethers (BzPE, EPE, and EPE-d₅, respectively) with different cis/trans isomer ratios were polymerized by BF₃O(C₂H₅)₂ at ?78°C in toluene, methylene chloride, and nitroethane solvents. Poly(propenyl alcohol) [poly(PA)] was also prepared by treating poly(BzPE) with HBr gas. The steric structure of these polymers was studied by ¹H- and ¹³C-NMR spectroscopy. The poly(EPE-d₅) obtained from a trans-rich monomer mixture was crystalline, while one from a cis-rich monomer mixture was amorphous. Poly(BzPE) was always amorphous. Poly(BzPE), poly(PA), and poly(EPE-d₅) gave ¹H-NMR spectra with two β-methine peaks, relative intensities of which depended on the geometric structure of the monomers. Their spectra of β-methyl protons decoupled from β-methine proton were also split into two peaks, relative intensities of which corresponded to those of the two α-methine peaks. ¹³C-NMR spectra of α-OCH₂ and β-CH₃ of poly(EPE), respectively, consisted of two peaks. These observations show that the poly(propenyl ethers) examined, whether crystalline or amorphous, have only two dyad structures (probably threo or erythro-meso and racemic), and that their α- and β-carbons have the same dyad structure, irrespective of the kind of the alkoxyl groups.     

1H- and 13C-NMR spectroscopic studies of tris(phenylthio)arsine and dimethyl(phenylthio)arsine

The proton and carbon-13 NMR spectra of solutions in CDCl₃ of dimethyl(phenylthio)arsine and tris(phenylthio)arsine where investigated. All resolved experimental resonances were assigned and the coupling constants determined by means of an iterative procedure employing the LAO-COON3 program. The spectra were simulated using Gaussian—Lorentzian lineshapes. The protons in the 2,6- and 3,5-positions were found to be equivalent. The resonances appear in the sequence δ_2,6 ⪢ δ_3,5 ⪢ δ₄ and δ_2,6 ⪢ δ₄ ⪢ δ_3,5 for dimethyl(phenylthio)arsine and tris(phenylthio)arsine, respectively. Whereas the protons in the 2,6-positions resonate at the same frequency (7.44 ppm) in the two compounds, the shifts for the 3,5- and 4-protons of tris(phenylthio)arsine are downfield from those of dimethyl(phenylthio)arsine. These differences are explained in terms of the hypothesis that the conformation of the rigid tris(phenylthio)arsine molecule does not allow overlap between the sulfur atomholding the lone electron pair and the π-ring orbital to the same extent as in dimethyl(phenylthio)arsine; in which the phenyl group can oscillate about an equilibrium position characterized by maximal p_s-π-ring overlap.     

Photocyclization of 2-(naphth-1-yl)-3-(thien-2-yl)propenoic acid and the total assignment of the 1H- and 13C-NMR spectra of the product

Photocyclization of the substituted 2-(naphth-1-yl)-3-(thien-2-yl)propenoic acid ( 3 ) in the presence of iodine and air in a benzene-cyclohexane mixture afforded a separable mixture of three compounds, phenanthro[2,1-b]thiophene-10-carboxylic acid ( 4 ), phenanthro[2,1-b]thiothene ( 5 ), and naphtho[1,8-cde]-thieno[3,2-g][2]benzopyran ( 6 )     

Investigation of the intramolecular structure of styrene–ethylmethacrylate copolymers by 1H- and 13C-NMR: Reassignment of 1H-NMR spectra

The compositions and sequence distributions of homogeneous styrene (S)–ethyl methacrylate (E) copolymers, obtained by low conversion solution polymerization have been studied by ¹H- and ¹³C-NMR. A new set of peak triad assignments was proposed for the δ 2.1–4.2 ppm region in the ¹H-NMR spectrum, whereby the reactivity ratios of r_S = 0.59 and r_E = 0.50 were used to establish this new assignment. The EEE and SSS blocks, present in these copolymers, have a high degree of syndiotacticity (σ_EE = 0.23, σ_SS = 0.39), whereas the ESE units are exhibiting a slight tendency toward isotacticity (σ_ES = 0.66).     

Differentiation and quantification of synthetic phosphatidylethanol (PEth) homologues by 1H- and 13C-NMR in polar organic solvents

Various phosphatidylethanol (PEth) derivatives, the corresponding reversed positional isomers (RPI-PEths), lyso-PEth-16:0, and penta-deuterium-labeled PEth analogs (d5-PEths), were synthesized by enzyme-independent synthetic routes. A general solvent system consisting of a mixture of acetone-d6 and methanol-d4 (97:3; v/v) was found to provide a good solubilizing capacity and excellent hydrogen-1 NMR (¹H-NMR) peak resolution of various PEth homologues. Analytical differentiation of PEth from the corresponding RPI-PEth by carbon-13 NMR (¹³C-NMR) was demonstrated by comparison of the ¹³C-NMR signals of the carbonyl groups, the allylic positions, and of the β-carbons. An exemplary stable long-term room temperature, DMSO-d6-based, and proton-sensitive quantitative nuclear magnetic resonance (¹H-qNMR) independently quantified calibrator comprising PEth-16:0/18:1 for liquid chromatography (tandem) mass spectrometry (LC-MS/MS) analytical applications were prepared by employment of sodium dodecyl sulfate (SDS) as a solubilizing additive. In summary, novel hypothetically occurring PEth derivatives, e.g., RPI-PEths, have been independently synthesized with regio- and stereochemical control. Use of polar organic solvents, e.g., mixtures of acetone-d6 and methanol-d4 or DMSO-d6, improves spectral line shapes as compared to traditional hydrophobic solvents and allow for analytical differentiation between closely related PEth derivatives, as well as LC-MS/MS-independent concentration determination of dissolved single species by employment of ¹H-qNMR.

A Study of N-Butyl-(all-trans-retinylidene)amine and Its Protonated Species by 1H- and 13C-NMR. Spectroscopy

The Schiff base of all-trans-retinal was investigated in organic solution by ¹H- and ¹³C-NMR. at high field. Complete assignment of the ¹H-NMR. peaks of N-butyl-(all-trans-retinylidene)amine ( 2 ) and the N-butyl-(all-trans-retinylidene)-ammonium ion ( 3 ) was achieved by INDOR (internuclear double resonance). The vicinal proton coupling constants of the polyene chain show that the π-bond orders remain unchanged in N-butyl-(all-trans-retinylidene)amine relative to all-trans-retinal ( 1 ), but change towards larger π-delocalization in the N-butyl-(all-trans-retinylidene)ammonium ion. At ?-61° only one isomer of N-butyl-(all-trans-retinylidene)ammonium was observed. This was shown to be trans at the imine linkage and independent of the solvent. The trifluoroacetic acid counter-ion can approach the positive charge of the N-atom in the weakly polar solvent dichloromethane but not in the leveling solvent methanol. In dichloromethane the nature of the 1:1 complex is a H-bonded (O^?…H-N⁺) ion-pair whose rate of breaking and forming is rapid at RT. Strong stabilization of the ion-pair resulted from homo-conjugation with a second molecule of trifluoroacetic acid. Excess of acid efficiently diminished the isomerization rate at the C,N-bond.     

(Butadiene)tricarbonylosmium synthesis and structural comparison with the Fe- and Ru-complexes based on 1H- and 13C-NMR. Spectroscopy

The photochemical synthesis of the title complex from 1,3-butadiene and dodecacarbonyltriosmium is described. The ¹H-NMR. and H-coupled ¹³C-NMR. spectra are analyzed completely and the H, H- and C,H-coupling constants compared with the data of the corresponding Fe- and Ru-complexes. One-bond ¹³C, ¹³C-coupling constants are reported for a series of complexed 1,3-dienes. All data are consistent with an increasing distortion from planarity of the C,H-skeleton at the terminal diene C-atoms in the sequence Fe → Ru → Os.     

Stereoregularity of poly(α-methylvinyl alkyl ether)s determined by 1H- and 13C-NMR spectroscopy

α-Methylvinyl methyl ether, ethyl ether, and isobutyl ether were polymerized under various polymerization conditions and the structure of the polymers was determined by ¹H- and ¹³C-NMR spectroscopy. α-Methyl and β-methylene carbon spectra of poly(α-methylvinyl isobutyl ether) showed splitting and were analyzed by triad and tetrad sequences. β-Methylene carbon spectra of poly(α-methylvinyl ethyl ether) also showed splitting. When Eu(fod)₃ was added, α-methyl and methoxy proton spectra in benzene of poly(α-methylvinyl methyl ether) showed splitting assigned to triad tacticities. All the polymers obtained in polar solvents exhibited an increase in syndiotacticity. The polymerization mechanism is discussed.     

An Au(III) complex of glycyl- S -serine: a linear polarized IR and 1H- and 13C-NMR investigation

The structure of a mononuclear Au(III) complex of the dipeptide glycyl-S-serine (Gly-Ser) has been predicted using solid-state linear dichroic IR (IR-LD) spectroscopy, based on an orientation technique in a nematic liquid crystal suspension. Results are compared with data from ¹H- and ¹³C-NMR, MS, elemental analysis, thermogravimetry and differential scanning calorimetry. The metal ion is coordinated as a tridentate through NH₂, N (from deprotonated amide) and O (COO^?) groups to form [Au(C₅H₉N₂O₄)Cl], with the fourth position of the square-planar coordination sphere being completed by a Cl^? ion.     

Studies of the thiadiazine, taurolidine-I. Identification of the molecular species present in aqueous solutions by (1)H- and (13)C-NMR spectroscopy

The equilibria in deuterium oxide solutions of the diamine, 4,4'-methylenebis(tetrahydro-1,2,4-thiadiazine-1,1-dioxide), were studied using highfield (1)H- and (13)C-NMR with the aid of solutions of tetrahydro-2H-1,2,4-thiadiazine-1,1-dioxide (taurultam), its two N-methyl detivatives and methylene glycol. Comparison of the (1)H-NMR spectrum of taurolidine with the one obtained from a mixture of taurultam and methylene glycol indicated that the same equilibria exists in both these solutions. It was concluded that taurolidine, taurultam and its 4-hydroxymethyl adduct and methylene glycol are the major components present. To facilitate the interpretation of the (13)C-spectra, (13)C-enriched methylene glycol was added to solutions of taurultam. The (13)C-studies confirmed the (1)H-NMR study.     

Assignment of the 1H- and 13C-NMR spectra of phenanthro[1,2-b]thiophene through the concerted application of two-dimensional NMR spectroscopic techniques

Two-dimensional nmr spectroscopy, by virtue of its second frequency domain which permits the segregation of spectral information along two frequency axes, considerably simplifies many assignment problems and facilitates others which may be impossible using conventional nmr methodology. A compound which falls into the latter category of assignment problem is phenanthro[1,2-b]thiophene. The assignment of the ¹H- and ¹³C-nmr spectra of phenanthro[1,2-b]thiophene are, however, reported through the concerted application of two-dimensional nmr techniques. Experiments utilized in making the assignments included: auto-correlated homonuclear (COSY) two-dimensional spectroscopy; heteronuclear two-dimensional J-resolved spectroscopy; proton-carbon chemical shift correlation two-dimensional spectroscopy; and two-dimensional ¹³C-¹³C double quantum coherence spectroscopy.     

Ultrahigh-resolution (1)H-(13)C HSQC spectra of metabolite mixtures using nonlinear sampling and forward maximum entropy reconstruction

To obtain a comprehensive assessment of metabolite levels from extracts of leukocytes, we have recorded ultrahigh-resolution 1H-13C HSQC NMR spectra of cell extracts, which exhibit spectral signatures of numerous small molecules. However, conventional acquisition of such spectra is time-consuming and hampers measurements on multiple samples, which would be needed for statistical analysis of metabolite concentrations. Here we show that the measurement time can be dramatically reduced without loss of spectral quality when using nonlinear sampling (NLS) and a new high-fidelity forward maximum-entropy (FM) reconstruction algorithm. This FM reconstruction conserves all measured time-domain data points and guesses the missing data points by an iterative process. This consists of discrete Fourier transformation of the sparse time-domain data set, computation of the spectral entropy, determination of a multidimensional entropy gradient, and calculation of new values for the missing time-domain data points with a conjugate gradient approach. Since this procedure does not alter measured data points, it reproduces signal intensities with high fidelity and does not suffer from a dynamic range problem. As an example we measured a natural abundance 1H-13C HSQC spectrum of metabolites from granulocyte cell extracts. We show that a high-resolution 1H-13C HSQC spectrum with 4k complex increments recorded linearly within 3.7 days can be reconstructed from one-seventh of the increments with nearly identical spectral appearance, indistinguishable signal intensities, and comparable or even lower root-mean-square (rms) and peak noise patterns measured in signal-free areas. Thus, this approach allows recording of ultrahigh resolution 1H-13C HSQC spectra in a fraction of the time needed for recording linearly sampled spectra.     

The elucidation of the 1H- and 13C-NMR spectra of bis[N,N-di(2,3-epoxypropyl)-4-aminophenyl]methane (TGMDA) and composite with bis(4-animophenyl)sulfone (DDS) using two-dimensional fourier transform techniques

The application of Fourier transform (FT) two-dimensional nuclear magnetic resonance spectroscopy to the study of the composite of bis[N,N-di(2,3-epoxypropyl)-4-aminophenyl] methane (TGMDA) and the curing agent bis(4-aminophenyl)sulfone (DDS) is discussed. The combination of 2D-J resolved and homonuclear (proton) shift correlated experiments permits the complex proton spectrum due to the glycidylamine moiety to be completely elucidated. The potential utility of this in the study of the aging of prepreg is briefly discussed.     

The trans-Influence in Platinum (II) Complexes. 1H- and 13C-NMR. and X-ray structural studies of tridentate Schiff's base complexes of platinum (II)

¹H- and ¹³C-NMR. data are reported for the complexes [Pt (1) L] and [Pt (2) L]; 1 = OC₆H₄CH ? NCH₂CH₂O, 2 = OC₆H₄CH ? NC₆H₄O; L = PR₃, AsR₃, C ? N (cyclohexyl), DMSO, pyridine, secondary amine. The molecular structures of [Pt (2) (NHEt₂)] (I) and [Pt (2) (PPh₃)] (II) have been determined by X-ray analysis. Relevant bond distances for I: Pt-N (amine) = 2.076 Å, Pt-N (imine) = 2.017 Å, Pt-O = 1.992 Å and 2.002 Å; for II: Pt-P = 2.248 Å, Pt-N = 2.064 Å, Pt-O = 1.964 and 2.005 Å. Both the solid and solution state data are interpreted in terms of differences in the trans influence of the ligand L. The question of metal-ligand d-p π back bonding to the imine is discussed.     

Long range optimized two-dimensional proton-carbon chemical shift correlation. Application in the total assignment of the 1H- and 13C-NMR spectra of 9-methylphenanthro[4,3-a]dibenzothiophene

The utilization of the long range optimized proton-carbon chemical shift correlation experiment in the total assignment of the proton and carbon nmr spectra of 9-methylphenanthro[4,3-a]dibenzothiophene is described. The experiment was employed in concert with conventional proton-carbon chemical shift correlation, heteronuclear relayed coherence transfer and broad band homonuclearly decoupled proton-carbon chemical shift correlation experiments. The experiments in combination offer a useful alternative to the ¹³C-¹³C double quantum coherence experiments, providing significantly better sensitivity and nearly the same capabilities.     

Fentanyl and its analogue N-(1-phenylpyrazol-3-yl)-N-[1-(2-phenylethyl)-4-piperidyl]propanamide: 1H- and 13C-NMR spectroscopy,X-ray crystallography,and theoretical calculations

The oxalate salts and free bases of fentanyl and N-[1-(2-phenylethyl)-4-piperidyl]-N-(1-phenyl-4-pyrazolyl)propanamide, a new lead compound for long-acting analgesia, have been characterized by (1)H- and (13)C-NMR spectroscopy. The crystal structure of the hydrochloride of N-[1-(2-phenylethyl)-4-piperidyl]-N-(1-phenyl-4-pyrazolyl)propanamide monohydrate has been determined. Two centrosymmetrically related cations, joined through C(phenyl)-H em leader pi contacts, encapsulate a large void that contains pairs of anions and bridged water molecules into a zero-dimensional (0D) supramolecular motif. The cations are linked to this framework via N(+)H em leader Cl(-) contacts. GIAO/B3LYP calculations have been carried out to compare the experimental (13)C chemical shifts with the absolute shieldings thus calculated. The protonation of both molecules takes place on the piperidine ring (axial protonation), as has been verified both in the solid state (X-ray) and in solution (NMR).