Quantitative1H and13C NMR spectroscopies of cottonplant dioxane lignin

A comparative analysis has been made of the dioxane lignins of the stems, seedling shoots, and seed coats of the cotton plant. The ratio of p-hydroxyaromatic, guaiacyl, and syringyl units in the macromolecules of the lignins has been determined, and so have the amounts of functional groups and bonds. It has been established that the main difference between the dioxane lignins from seedling shoots and seed coats of the cotton plant, on the one hand, and the lignin from the woody stems, on the other hand is a lower content of syringyl and guaiacyl units in the former.Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 798–808, November–December, 1994.     

Destruction of aspen wood by the fungusPhanerochaete sanguinea quantitative1H and13C NMR spectroscopies of biologically degraded lignin

The lignin of mechanically ground aspen wood and lignins isolated from aspen wood attacked by the fungusPhanerochaete sanguinea have been investigated by quantitative¹H and¹³C NMR spectroscopies. It has been shown that the biodestruction of the lignin takes place through the cleavage of alkyl-aryl and aryl-aryl bonds and is accompanied by demethylation (demethoxylation) reactions, and the oxidation of C_α and C_γ atoms. In addition to reactions in which the C—C bonds are cleaved, the formation of ether bonds has been observed. An interconnection has been shown between the variations in the amount of functional groups, fragments, and the bonds in biolignins and the loss in mass of the wood. A method is proposed for evaluating the carbohydrate content in lignin preparations using the NMR method.     

1H and13C NMR spectra of biologically active compounds

The¹H and¹³C NMR spectra of diols of the hexachlorobicycloheptene and-heptadiene series, and also of the diacetates and sulfites corresponding to them, have been investigated. Criteria for the stereochemical assignment of the compounds mentioned on the basis of chemical shifts and spin-spin coupling constants have been determined.Institute of Chemistry, Bashkir Branch, USSR Academy of Sciences, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 439–443, May–June, 1988.     

四萜Methyl Sartortuoate 的分离和NMR归属

从采自海南岛三亚的扭曲肉芝软珊瑚Sarcophyton tortuosum中分离得到3个新四萜和1个已知四萜methyl sar-tortuoate (1). 利用HMQC, ¹H-¹HCOSY, HMBC等二维NMR方法首次对methyl sartortuoate (1)的所有¹H, ¹³C NMR信号进行了完全的归属.     

Metabolites of the pathogenic fungusVerticillium dahliae. I.1H and13C NMR spectra of the extracellular lipids

Summary From the culture liquid of the fungusV. dahliae an extract has been isolated which contains paramagnetic centers and causes the symptoms of verticillium wilt of the cotton plant. By chromatography and¹H and¹³C nuclear magnetic resonance it has been shown that this extract includes triglycerides and fatty-acid residues of the oleic series with various degrees of unsaturation.V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 453–458, July–August, 1975.     

1H and13C NMR spectra and the structure of a new coumarin, C-glycoside dauroside D, fromHaplophyllum dauricum

On the basis of chemical transformations,¹H and¹³C NMR spectra, the structure of dauroside D isolated fromHaplophyllum dauricum has been established as 6-C--D-glucopyranosyl-5,7-dihydroxycoumarin. Some interesting features of the¹H NMR spectra of its acetate have been reported and an assignment of the signals in its¹H and¹³C NMR spectra has been made. Dauroside D is the first natural coumarin C-glycoside.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 441–445, July–August, 1983.     

Withasteroids ofPhysalis. V. A study of the1H and13C NMR spectra of the withasteroids visconolide and 28-hydroxywithaperuvin C

The PMR and¹³C NMR spectra of new withasteroids — visconolide and 28-hydroxywithaperuvin C, isolated fromPhysalis viscosa L. — have been investigated. A detailed analysis of the spectral characteristics obtained is given. For visconolide is proposed the structure of 4,12,17,28-pentahydroxy-1-oxo-5, 6-epoxy-22R-witha-2,24-dienolide, and for 28-hydroxywithaperuvin C that of 6,14,17,20R, 28-pentahydroxy-l-oxo-22R-witha-2, 4, 24-trienolide.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 657–663, September–October, 1985.     

Structural analysis of alkylated coal by 1H and 13C NMR spectroscopy

Summary A method is presented for derivation of a series of structural parameters describing the average molecule of soluble butylated coal. It is based on ¹H and ¹³C NMR spectral data, molecular mass measurement and ultimate analysis. Average structural models of coals can be constructed in this way.

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Strukturanalyse von alkylierter Kohle mit Hilfe der ¹H- und ¹³C-NMR-Spektroskopie

Zusammenfassung Ein Verfahren wird vorgestellt zur Ableitung einer Reihe von Strukturparametern, die das Durchschnittsmolekül von löslicher butylierter Kohle beschreiben können. Es beruht auf ¹H- und ¹³C-NMR-Spektraldaten, Messungen der Molekülmasse sowie der Elementaranalyse. Durchschnittliche Strukturmodelle von Kohlen können dadurch erstellt werden.

     

1H,13C and17O NMR studies of cumene hydroperoxide coordination to Cr(AA)3

It has been established that the outer sphere coordination of cumene hydroperoxide to Cr(AA)₃ is due to both the formation of hydrogen bonds between hydroxyl proton and chelate oxygen atoms and the --interactions between the aromatic ring and chelate -system.

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, - Cr(III) , --- - .

     

紫杉醇的核磁共振谱及其分子几何构型的从头算研究

应用规范不变原子轨道GIAO法在HF/6 31G水平计算了MM3、PM3和HF/STO 3G三种最优分子构型下紫杉醇的δ 1H NMR和δ 13C NMR.对NMR化学位移计算值与实验值的对比和误差的统计和分析表明,采用HF/STO 3G优化的几何构型计算得到的化学位移误差最小，因此这一构型与实际分子最为接近.从理论构型得到4 OAc与3′ H的距离为0.266 3 nm，4 OAc与3′ Ph的距离为0.310 4 nm，4 OAc与2 OCOPh的距离为0.370 7nm，支持了Williams等关于紫杉醇分子内存在NOE (nuclear overhauser effect)效应及Velde等关于在极性溶剂中4 OAc与3′ Ph、2 OCOPh形成分子内疏水簇的观点.     

Configuration and conformation of methyl 2,3-anhydro-4-deoxy-pyranosides by 1H and 13C NMR spectra

¹³C NMR spectra of 24 methyl 2,3-anhydro-4-deoxy-pento and hexopyranosides have been obtained. ¹H NMR spectra were also recorded for comparison purposes. The ¹³C NMR data can be used for differentiation of the stereo-isomeric epoxide configuration. ¹H and ¹³C NMR spectra give some insight, though still of qualitative nature, into conformation of epoxy compounds.     

NMR study (1H, 13C and 29Si) of the methylallylsilanes

¹H, ¹³C and ²⁹Si NMR data for the compounds (CH₃)_xSi(CH₂CHCH₂)_4-x are reported. The ¹H resonances from the π system are indicative of the electron-supplying inductive effect (+I) of the (CH₃SiCH₂, moiety but the corresponding ¹³C_π chemical shifts seem to be influenced by a sterically induced polarization of the C-H bonds. The ¹³C_All, ¹³C_Me and ²⁹Si chemical shift data reveal an important neighbour anisotropy contribution originating from the π system. Ultraviolet study of the compounds mentioned above gives indication of a σ—π conjugation in accordance with PES and ab initio results [1—5]. The trend observed in the various coupling constants is too small to be Interpreted.     

1H and 13C NMR spectral analysis of some necines of toxic pyrrolizidine alkaloids

Summary The total assignment of the ¹H and ¹³C NMR spectra of the necines of toxic pyrrolizidine alkaloids (retronecine, heliotridine, crotanecine, otonecine), their hydrochlorides and their N-oxides has been performed. The characteristic chemical shift differences between retronecine and heliotridine, as well as the protonation and N-oxidation shift effects in NMR studies of necines at the corresponding position are proposed to be an additional assignment aid. The assignment of the spectra was achieved by the concerted use of 2D correlation spectroscopy.Dedicated to Prof. Dr. Dr. Dres. h. c. Herbert Oelschläger, Frankfurt/Main, on the occasion of his 70th birthday     

A study of the properties and13C NMR spectra of pinifolic acid and its derivatives

The properties and¹³C NMR spectra of pinifolic acid (13S-labd-8,17-ene-15,18-dioic acid), its monomethyl ester, its dimethyl ester, its dicyclohexylammonium salt, dihydropinifolic acid, 18-hydroxy-13S-labd-8(17)-en-15-oic acid, the cyclohexylammonium salt of the monomethyl ester, the bis(diethylammonium) salt, pinifodiol (13S-labd-8(17)-ene-15,18-diol), the acetate of 18-hydroxy-13S-labd-8(17)-en-15-oic acid, and the diacetate of pinifodiol have been studied.Institute of Physical Organic Chemistry of the Academy of Sciences of the Belorussian SSR, Minsk. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 568–572, September–October, 1981.     

Study of the photolysis of arenetricarbonylchromium complexes by IR,UV and 1H and 13C NMR spectroscopy

The mechanism of photolysis of arenetricarbonylchromium complexes is investigated by a number of spectral techniques. Experimental data are obtained in favour of the formation during the ArCr(CO)₃ photolysis of a multicenter complex, photodecay of which leads to the formation of chromium hexacarbonyl. A mechanism for the photolysis of arenetricarbonylchromium complexes is proposed.     

NMR (1H, 13C, 29Si) study of some allylhalogenosilanes

¹H, ¹³C and ²⁹Si NMR spectra of the allylchlorosilanes (CH₂CH-CH₂-)_xSiCl_4?x and of triallylbromosilane have been analysed. Results are discussed in terms of inductive and steric effects and of contributions of diamagnetic anisotropy. There is no conclusive evidence for (p-d)π conjugation.     

13C and 1H NMR spectra of monosubstituted ferrocenes containing a chiral centre in the substituent

The ¹³C-{¹H} and ¹H NMR spectra of ferrocenyl chalkones (β-benzoylvinylferrocene add cinnamoylferrocene) and their iron carbonyl complexes were recorded. Splitting of the resonances of both α- and β-substituted cyclopentadienyl ring atoms was found in ¹³C-{¹H} NMR spectra of all complexes. In ¹H NMR spectra splitting of the resonances of the substituted cyclopentadienyl ring α-protons was detected only in the case of (cinnamoylferrocene)iron tricarbonyl. The splitting effect mentioned can be due to thesochsochronism (magnetic nonequivalence) of all carbon and hydrogen nuclei because of the iron carbonyl fragment coordination oauses the substituent to become the chiral group. The coordination of iron carbonyl group results in a reduction of the conjugation in the α,β-unsaturated ketone system. This phenomenon is discussed on the basis of ¹³C-{¹H} and ¹H NMR data.     

Substituent Effects on 13C NMR and 1H NMR Chemical Shifts of CH=N in Multi-substituted Benzylideneanilines

Fifty-three samples of multi-substituted benzylideneanilines XArCH=NArYs (abbreviated XBAYs) were synthesized and their NMR spectra were determined. An extensional study of substituent effects on the ¹H NMR chemical shifts (^δH(CH=N)) and ¹³C NMR chemical shifts (^δC(CH=N)) of the CH=N bridging group from di-substituted to multi-substituted XBAYs was made based on a total of 182 samples of XBAYs, together with the NMR data of other 129 samples of di-substituted XBAYs quoted from literatures. The results show that the substituent specific cross-interaction effect parameter \begin{document} $\left(\Delta\left(\displaystyle\sum\sigma\right)^2\right)$ \end{document} plays an important role in quantifying the ^δC(CH=N) values of XBAYs, but it is negligible for quantifying the ^δH(CH=N) values; the other substituent parameters also present different influences on the ^δC(CH=N) and ^δH(CH=N). On the whole, the contributions of X and Y to the ^δC(CH=N) of XBAYs are balanced, but the ^δH(CH=N) values of XBAYs mainly rely on the contributions of X.