NMR investigation of alkaloids I.13C NMR spectra and stereochemistry of pentacyclic oxindole alkaloids of the heteroyohimbine group of the epiallo and allo series

The¹³C NMR spectra of pentacyclic oxindole alkaloids of the heteroyohimbine group of the allo and epiallo series have been studied and an assignment has been made of the CSs of the carbon atoms. Characteristic differences have been noted in the¹³C CSs of the C₂, C₃, C₇, C₁₄, C₁₅, and C₁₉ carbon atoms that may be useful for solving stereochemical problems in new bases of this series from their¹³C NMR spectra.Communicated at the All-Union Conference on Recent Advances in High-resolution NMR spectroscopy, Tashkent, September, 1979 [1].Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 217–224, March–April, 1980.     

Adduct of nonamethylferrocenecarbaldehyde with HBF4 and its transformations

Some reactions of the adduct of nonaniethylferrocenecarbaldehyde with HBF₄, [Me₅C₅FeC₅Me₄CH⁺(OH)]BF₄ ^–, and its transformation into the paramagnetic complex [Me₅C₅Fe^+-C₅Me₄CH=O]BF₄ ^– were studied. The structure of the complex was established from the chemical properties, the data from IR spectroscopy, mass spectrometry, and¹H,¹³C, and¹⁹F NMR spectroscopy and confirmed by independent synthesis.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp, 2979–2983, December, 1996.     

Electrophilic substitution of 1-methylindeno-1H-[2,1-b]pyridine

It is shown that electrophilic substitution of 1-methylindeno-1H-[2,1-b]pyridine takes place at the C₉ atom in the case of acylation (acetylation, benzoylation, and formylation), bromination, and nitration. Data from the ¹³C NMR spectrum of this pseudoazulene confirm sp² hybridization of the C₉ atom.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1238–1240, September, 1982.     

Structure of lilidine

The new alkaloid lilidine, isolated for the first time from the epigeal part ofLilium martagon has been studied by special methods. It has the composition B₅H₆NO₂, mp 118–110°C, []_D-26.3°. The¹H and¹³C NMR spectra were studied in detail. The values of the direct and long-range spin-spin coupling constants between the¹³C carbon nuclei and the¹H nuclei of the alkaloid molecule were measured with the aid of¹³C-[{su1}H] selective heteronuclear double resonance. The structure of 5-hydroxy-3-methyl-3-pyrrolin-2-one is suggested for lilidine.Institute of the Chemistry of Plant Substances of the Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 692–696, September–October, 1987.     

Copper(II) and Nickel(II) Alkylxanthate Complexes (R = C2H5, i-C3H7, i-C4H9, s-C4H9, and C5H11): EPR and Solid-State 13C CP/MAS NMR Studies

Alkylxanthate complexes of the general formula [M{S(S)COR}₂] (M = Ni, ⁶³Cu, and ⁶⁵Cu; R = C₂H₅, i-C₃H₇, i-C₄H₉, s-C₄H₉, and C₅H₁₁) were synthesized and studied by EPR and high-resolution solid-state ¹³C CP/MAS NMR. In the copper(II) complexes stabilized in the matrix of nickel(II) compounds, square planar chromophores [CuS₄] are characterized by rhombic distortion (EPR data). Experimental EPR spectra were simulated at the second order of perturbation theory. Nickel(II) complexes were characterized by ¹³C NMR spectra. In all cases, the –OC(S)S– groups were found to exhibit intramolecular structural equivalence.     

Topological incremental scheme for calculating13C NMR chemical shifts in polysubstituted benzenes with substituents of one kind

A new topological approach to predicting the¹³C NMR chemical shifts of polysubstituted benzenes has been proposed (in the example case of compounds with substituents of one kind of the type C₆H_6–nX_n). The collective interactions of several substituents X [X=CH₃, C₂H₅, iso-C₃H₇, CF₃, COOH, f, Cl, Br, Si(CH₃)₃] have been expressed in the framework of a regression treatment in terms of two-particle increments. The chemical shift of each carbon atom has been represented in the form of an equation containing 17 parameters. The calculation scheme can be transformed and expanded for use even in the calculation of the spectra of compounds not previously studied. The calculated shifts for some previously investigated compounds and some compounds not previously investigated have been presented. The error in reproducing chemical shifts is equal to 0.2–0.3 ppm (and may be as high as 0.8 ppm for only a few measurements).V. I. Vernadskii Institute of Geochemistry and Analytical Chemistry, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 2, pp. 62–71, March–April, 1991.     

Coordination Germanium(IV) Compounds with Nitrosubstituted Benzoylhydrazones of Salicylaldehyde

New germanium(IV) complexes with N-[X-benzoyl]hydrazones of salicylaldehyde (X-H₂L, where X = 2-, 3-, and 4-NO₂; H₂L = C₆H₄–CO–NH–NCH–C₆H₄OH) with the compositions [Ge(2-NO₂–L)₂], [Ge(3-NO₂–L)₂], and [Ge(4-NO₂–L)₂] were synthesized. The data of IR, UV, and ¹H, ¹³C NMR spectroscopy showed that the complexes had an octahedral structure and ligand coordination through the nitrogen atom of the azomethine group and two oxygen atoms of the doubly deprotonated form of the ligand. The thermal stability of the complexes was studied. The specific features of the mass spectrometric behavior of the substances in the gas phase under electron impact were considered.     

Carbon-13 kinetic isotope effects in the decarbonylation of lactic acid of natural isotopic composition in phosphoric acid medium

The¹³C kinetic isotope effect fractionation in the decarbonylation of lactic acid (LA) of natural isotopic composition by concentrated phosphpric acids (PA) and by 85% H₃PO₄ has been studied in the temperature interval of 60–150°C. The values of the¹³C₍₁₎ isotope effects in the decarbonylation of lactic acid in 100% H₃PO₄, in pyrophosphoric acid and in more concentrated phosphoric acids are intermediate between the values calculated assuming that the C₍₁₎–OH bond is broken in the rate-controllin gstep of dehydration and those calculated for rupture of the carbon-carbon bond in the transition state. In the temperature interval of 90–130°C the experimental¹³C fractionation factors determined in concentrated PA approach quite closely the¹³C fractionation corresponding to C₍₂₎–C₍₁₎ bond scission. the¹³C₍₁₎ kinetic isotope effects in the decarbonylation of LA in 85% orthophosphoric acid in the temperature range of 110–150°C coincide with the¹³C isotope effects calculated assuming that the frequency corresponding to the C₍₁₎–OH vibration is lost in the transition state of decarbonylation. A change of the mechanism of decarbonylation of LA in going from concentrated PA medium to 85% H₃PO₄ has been suggested. A possible secondary¹⁸O and a primary¹⁸O kinetic isotope effect in decarbonylation of lactic acid in phosphoric acids media have been discussed, too.     

Structure of aerugine from Pseudomonas aeruginosa

A new optically active phenolic alkaloid with the composition C₁₀H₁₁NO₂S, mp 85–88°C, []_D +28° (c 1.0; chloroform) (I) has been isolated from the microorganismPseudomonas aeruginosa (strain 590) and has been called aerugine. The action of diazomethane gave an O-methyl derivative (II). On the basis of the formation of ortho-cresol by the hydrogenolytic desulfuration reaction, a study of the IR, mass, and PMR spectra and (I) and its acetyl derivative (III), and also the¹³C NMR spectrum of (I), the structure of 4-hydroxymethyl-2-(o-hydroxyphenyl)-2-thiazoline has been established for aerugine. The spectral characteristics of the compounds mentioned are given.Institute of the Chemistry of Plant Substances of the Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 553–558, July–August, 1987.     

Silylotropy and the29Si NMR spectrum of 2-[dimethyl(pentafluorophenyl)siloxy]-2-penten-4-one

Conclusions ¹H,¹³C, and²⁹Si NMR spectroscopy was used to study the structure and silylotropy of 2-[dimethyl(pentafluorophenyl)siloxy]-2-penten-4-one. The temperature dependence of the²⁹Si NMR chemical shifts indicated the existence of an intermediate with pentacoordinated silicon.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1424–1425, June, 1986.     

Preparation of new dinuclear half-titanocene complexes with ortho- and meta-xylene linkages and investigation of styrene polymerization

Half-titanocene is well-known as an excellent catalyst for the preparation of SPS (syndiotactic polystyrene) when activated with methylaluminoxane (MAO). Dinuclear half-sandwich complexes of titanium bearing a xylene bridge, (TiCl₂L)₂{(μ-η⁵, η⁵-C₅H₄-ortho-(CH₂–C₆H₄–CH₂)C₅H₄}, (4 (L = Cl), 7 (L = O-2,6-iPr₂C₆H₃)) and (TiCl₂L)₂{(μ-η⁵, η⁵-C₅H₄-meta-(CH₂–C₆H₄–CH₂)C₅H₄} (5 (L = Cl), 8(L = O-2,6-iPr₂C₆H₃)), have been successfully synthesized and introduced for styrene polymerization. The catalysts were characterized by ¹H- and ¹³C NMR, and elemental analysis. These catalysts were found to be effective in forming SPS in combination with MAO. The activities of the catalysts with rigid ortho- and meta-xylene bridges were higher than those of catalysts with flexible pentamethylene bridges. The catalytic activity of four dinuclear half-titanocenes increased in the order of 4 < 5 < 7 < 8. This result displays that the meta-xylene bridged catalyst is more active than the ortho-xylene bridged and that the aryloxo group at the titanium center is more effective at promoting catalyst activity compared to the chloride group at the titanium center. Temperature and ratio of [Al]:[Ti] had significant effects on catalytic activity. Polymerizations were conducted at three different temperatures (25, 40, and 70 °C) with variation in the [Al]:[Ti] ratio from 2000 to 4000. It was observed that activity of the catalysts increased with increasing temperature, as well as higher [Al]:[Ti]. Different xylene linkage patterns (ortho and meta) were recognized to be a principal factor leading to the characteristics of the dinuclear catalyst due to its different spatial arrangement, causing dissimilar intramolecular interactions between the two active sites.     

Direct hydrogen-1, carbon-13, and nitrogen-15 NMR study of magnesium(II)-isothiocyanate complexing

A hydrogen-1, carbon-13, and nitrogen-15 NMR study of magnesium(II)-isothiocyanate complexation in aqueous mixtures has been completed. At temperatures low enough to slow proton and ligand exchange, separate¹H,¹³C, and¹⁵N NMR signals are observed for coordinated and bulk water molecules and anions. The¹H NMR spectra reveal signals for the hexahydrate and the mono-through triisothiocyanato complexes, as well as two small signals attributed to [Mg(H₂O)₅(OH)]¹⁺ and [Mg(H₂O)₄(OH)(NCS)]. Accurate hydration numbers were obtained from signal area integrations at each NCS^– concentration. In the¹⁵N NMR spectra, signals also were observed for the mono-through triisothiocyanato complexes, and a small signal believed to be due to [Mg(H₂O)₄(OH)(NCS)]. Coordination number contributions for NCS^– were measured from these spectra and when combined with the hydration numbers they totalled essentially six at each anion concentration. Signals for [Mg(H₂O)₅(NCS)]¹⁺ through [Mg(H₂O)₃(NCS)₃]^1– also were observed in the¹³C NMR spectra and the area evaluations were comparable to the¹⁵N NMR results. An analysis of the magnitude and sign of the coordinated NCS^– chemical shifts identified the nitrogen atom as the anion binding site. All spectra indicated [Mg(H₂O)₅(NCS)]¹⁺ and [Mg(H₂O)₄(NCS)₂] were the dominat isothiocyanato complexes over the entire range of anion concentrations. The inability to detect evidence for complexes higher than the triisothiocyanato reflects the competitive binding ability of water molecules and perhaps the decreased electrostatic interaction between NCS^– and negatively charged higher complexes.     

13C NMR spectra of bicyclo[3.3.1]nonanones and their derivatives

Conclusions An assignment was made of the lines in the¹³C NMR spectra of the mono- and diketones of the bicyclo[3.3.1]nonane series, and of the hydrolysis products of bicyclo[3.3.1]nonane-2,9-dione and its 7-benzoyloxy derivative.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2386–2389, October, 1979.     

Synthesis, characterizations and crystal structures of new organoantimony(V) complexes with various isomers of fluoromethylbenzoate ligands

Six new organoantimony(V) complexes containing various isomers of fluoromethylbenzoate ligands [RC₆H₃COO]₂SbPh₃ and [RC₆H₃COO]SbPh₄ [R = 3-F-4-(CH₃) (1, 4), 4-F-2-(CH₃) (2, 5), 5-F-2-(CH₃) (3, 6)] have been synthesized by the reactions of triphenylantimony(V) dichloride or tetraphenylantimony(V) bromide with various isomers of fluoromethylbenzoate ligands in 1:2 or 1:1 stoichiometries. All the complexes have been characterized by elemental analysis, IR and NMR [¹H, ¹³C and ¹⁹F] studies. The crystal structures of complexes 1, 3, 4, 5 and 6 have been determined by X-ray single crystal diffraction. The structure of complexes show that the five-coordinated antimony(V) atom adopts a distorted trigonal bipyramidal geometry. Furthermore, weak but significant intermolecular C–H···O, C–H···F hydrogen bonds, C–H···pi stacking lead to aggregation and assembly of these complexes into 1D and 2D supramolecular frameworks.     

Influence of the Structure of Nonionic Surfactants and the Length of Alkyl Substituents of Calix[4]resorcinarenes on Their Solubility, Acid–Base, and Complexation Properties

Regularities of solubilization of calix[4]resorcinarenes (H₈L) with the variable length of hydrophobic radicals (R = CH₃, C₃H₇, C₅H₁₁, C₇H₁₅, C₈H₁₇, C₉H₁₉, C₁₁H₂₃) by the micelles of nonionic surfactants Triton X-100 and Triton X-405 in aqueous solutions were studied using solubility measurements. It was found that the solubilization capacity of surfactant micelles with respect to H₈L and [H₄L]^4– depends on the extension (thickness) of their polar layers. It was shown by means of potentiometric titration that, in solutions of nonionic surfactants, the constants of the interaction between tetraanions [H₄L]^4– and tetrametylammonium ions depend on the structure and concentration of nonionic surfactants and the hydrophobicity of H₈L molecules. A change in the affinity of the [H₄L]^4– anions for protons and tetramethylammonium cations in nonionic surfactant solutions was revealed in relation to the length of substituents R and reagent concentrations.     

Regioselective aza-annulation to a heterocyclic ketene aminal: A new route to ethyl 1-oxo-2,3-dihydropyrido-[1,2-a]-(5H)-perimidine-4-carboxylates

Ethyl (1H-perimidin-2-yl)acetate 1 reacts with various acrylic acid chlorides 3 to afford new ethyl 1-oxo-2,3-dihydropyrido-[1,2-a]-(5H)-perimidine-4-carboxylates 4 by regioselective aza-annulation with the appropriate base. The ¹H, ¹³C NMR spectrum of some representative annulated perimidines 4 and C_β-acylated products 7 are discussed. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:523–528, 1998     

Conformation of monobenzyl ethers of piperidyl-containing acetylenic glycols,according to13C NMR spectroscopic data

In the¹³C NMR spectra of individual ()- and ()-epimers (through the C₄ carbon atom of the six-membered ring) of monobenzyl ethers of piperidyl-containing acetylenic glycols, it has been found that the chemical shifts of the epimers differ by as much as 3 ppm for the C₂, C₄, and C₆ carbon atoms. The most probable conformations of the epimers are suggested, including intramolecular hydrogen bonds between the proton of the OH group and the unshared electron pair of the nitrogen.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2780–2785, December, 1991.     

Isomerization in the partial ozonolysis of 1,4-cyclohexadiene

Conclusions The methyl ester of 6-oxo-4E-hexenoic acid is formed in the partial ozonolysis of 1,4-cyclohexadiene in MeOH-CH₂Cl₂ in the presence of NaHCO₃ at –70°C and the subsequent action of acetic anhydride and Et₃N.The authors thank L. M. Khalilov for assistance in interpreting the¹³C NMR spectrum.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1156–1157, May, 1989.