Specific intramolecular C-H...O interactions in 1-vinyl-2-formylimidazole and 1-vinyl-2-formylbenzimidazole studied by1H and13C NMR spectral data

According to the¹H and¹³C NMR spectral data, the vinyl group in 1-vinyl-2-formylimidazole and 1-vinyl-2-formylbenzimidazole istrans-oriented with respect to the formyl fragment, while the carbonyl group occupies theanti-position with respect to the N atom of pyridine cycle. A specific intramolecular C—H...O interaction of a weak hydrogen bond type is realized between the -H atom of the vinyl group and O atom of the carbonyl group.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1197–1201, May, 1996.     

Spectroscopic effects and intramolecular interactions in the1H and13C NMR spectra of five-membered N-vinyllactams

In 1-vinylpyrrolidone, 1-vinyl-1,2,4-triazole-5-ones, 1,3-divinylimidazolidine-2-thione, and 1-vinylbenzimidazole-1-thione the vinyl groups exist predominantly in the s-trans-, but in 1-vinyl-4,5-diphenylimidazole-2-ones in the s-cis(0)-conformations relative to the exocyclic heteroatom. In 1-vinylbenzimidazole-2-ones, 3-vinylbenzoxazole-2-one, and 1-vinylindole-2,3-diones the vinyl group is present as a mixture of the s-cis(0)- and s-trans(0)-conformations. According to¹H and¹³C NMR results there are specific intramolecular interactions in 1-vinylpyrrolidone and in 1,3-divinylimidazolidine-2-thione resembling weak hydrogen bonding between the -hydrogen atoms of the vinyl group and the oxygen or the sulfur atom. In 1-vinylsuccinimide, 2-vinylphthalimide, and 1,3-divinyl-4,5-diphenylimidazole-2-one there is the same type of interaction with the -cis-hydrogen atom of the vinyl group, while in 1,3-divinyl-1,2,4-triazole-5-one there is interaction between the same hydrogen atom and the nitrogen atom.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1983–1990, September, 1990.     

Specific C-H...N intramolecular interaction in 1-vinyl-2-cyanoethylthiobenzimidazole with the formation of a nine-membered intramolecular ring,according to1H and13C NMR data

In the¹H NMR spectrum of 1-vinyl-2-cyanoethylthiobenzimidazole, an abnormal downfield shift has been found in the signal of the -hydrogen atom of the vinyl group, and also an increase in the corresponding direct¹³C-¹H spin-spin coupling constant, in comparison with other 2-substituted benzimidazoles. This indicates a specific C-H...N intramolecular interaction in this molecule between the -hydrogen atom and the cyano nitrogen atom, forming a nine-membered intramolecular ring.Translated from Translated from Izvestiya Akademii Nauk SSSR No. 10, pp. 2285–2288, October, 1991.     

Study of internal rotation of the vinyl group in 1-, vinylpyridones by the AM-1 method

By the AM-1 method in the semirigid model approximation, the potential energy of internal rotation of the vinyl group has been calculated for 1-vinyl-2-pyridone, 1-vinyl-6-methyl-2-pyridone, and 1-vinyl-4-pyridone. The potential energy of internal rotation in the first and third of these molecules has two minima corresponding to torsion angles around the N-C bond approximately 0 and 180°, separated by barriers to internal rotation 3.99 and 2.94 kcal/mole, respectively. For the 1-vinyl-2-pyridone, the energy minimum at =180°, the s-cis(O) conformation, is 1.83 kcal/mole above the first minimum. For the 1-vinyl-6-methyl-2-pyridone, the torsion angles 0 and 180° correspond to energy maxima; the energy minima occur at 35° and 140°. In the harmonic oscillator approximation, the intervals of torsional vibrations of the vinyl group in these comopunds have been estimated. Data from the AM-1 calculation are in qualitative agreement with the available¹H and¹³C NMR data on the structure of 1-vinyl-2-pyridone, 1-vinyl-5-methyl-2-pyridone, and 1-vinyl-4-pyridone.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1367–1372, June, 1991.     

Structure of vinyl ethers of a number of azoles according to1H and13C NMR data and quantum-chemical calculations

NMR¹H and¹³C spectra have been used to establish the conformational states of a number of azole vinyl ethers and to study the nature of the conjugation of the unshared pair of electrons of the oxygen atom with the azole and vinyl moieties. The H¹ NMR spectra of the vinyl ethers of indazole, 4,5-diphenylimidazole, benzimidazole, and 1,2,4-triazole revealed anomalous downfield shifts of the signal of the proton of the vinyl group, which are attributed to specific interactions, resembling weak hydrogen bonds, between these hydrogen atoms and the pyridine nitrogen. This conclusion agrees with the results of quantum-chemical calculations for the vinyl ether of indazole.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1031–1036, May, 1990.     

Conformation of S-vinyl-N,N-diethyldithiocarbamate and C-H...S intramolecular interaction between atoms of olefinic hydrogen and sulfur of thiocarbonyl group according to1H and13C NMR data

According to¹H and¹³C NMR data, in S-vinyl-N,N-diethyldithiocarbamate, which exists primarily in the s-trans conformation with a syn-position of the thiocarbonyl and vinyl groups, a specific interaction C-H...S apparently takes place between the -hydrogen atoms of the vinyl group and the thiono sulfur.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1978–1982, September, 1990.     

Study of specific C-H...N intramolecular interactions in heteroaryl vinyl ethers,on the basis of factor analysis of1H and13C NMR spectral parameters

On the basis of a factor analysis of the¹H and¹³C NMR spectral parameters of the vinyloxy group in a broad series of aryl and heteroaryl vinyl ethers, it has been established that these parameters change mainly under the influence of the electronic effect of the aromatic fragment and specific C-H...N intramolecular interaction of the -hydrogen atoms of the vinyl group with an endocyclic nitrogen atom. It has been shown that the parameters most sensitive to the specific C-H...N. interaction are the chemical shifts of the -proton and -carbon of the vinyl group, and also the spin-spin coupling constant between these atoms.Translated from Izvestiya Akademii Nauk SSSR, No. 10, pp. 2289–2297, October, 1991.     

9-alkenylcarbazoles

The¹H and¹³C NMR spectra of 9-vinylcarbazole and its 3-chloro, 3,6-dichloro, and 3-nitro derivatives were recorded and studied. It is shown that electron-acceptor substituents reduce the shielding of the -carbon atom and the trans proton of the vinyl group. A good linear correlation between the chemical shifts of these nuclei and the Hammett _para ^– constants with the values (3.78 for¹³C and 0.28 for¹H_trans) is observed. It was established by comparison of the results with the¹H and¹³C NMR spectral parameters for some of the vinyl compounds that the degree of conjugation of the p electrons of nitrogen with the electrons of the double bond in 9-vinylcarbazoles is lower than in simple vinyl and vinyl phenyl ethers and vinyl acetate.See [25] for communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1368–1371, October, 1976.     

Study of C-H...N specific intramolecular interactions in heteroaryl vinyl ethers,by means of regression and cluster analysis of parameters of1H and13C NMR parameters

By means of regression and cluster analysis of the parameters of the¹ and¹³C NMR spectra of the vinyloxy group in a broad series of aryl and heteroaryl vinyl ethers, it has been proven statistically that these parameters are abnormal for ethers in which the vinyloxy group occupies a position adjacent to an endocyclic nitrogen atom; this is evidence for the existence of a C-H...N specific intramolecular interaction between the -hydrogen atoms of the vinyl group and the endocyclic nitrogen.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1344–1351, June, 1991.     

1-Methyl-2(3,4)-(1-vinylpyrrol-2-yl)pyridinium iodides: some structural features revealed by 1H and 13C NMR spectroscopy

The reactions of 2-, 3-, and 4-(1-vinylpyrrol-2-yl)pyridines with methyl iodide afford the corresponding quaternary salts. Analysis of their ¹H and ¹³C NMR spectra showed that the quaternization of the nitrogen atom considerably enhances the -acceptor effect of the pyridine ring on the pyrrole ring and on the vinyl group. 1-Methyl-2-(1-vinylpyrrol-2-yl)pyridinium iodide contains no weak intramolecular C--H...N hydrogen bond present in the starting compound.     

Specific C-H⋯N intramolecular interactions in the vinyloxy- and vinylthiopyridine series

A weak hydrogen bond with the participation of the vinyl group -hydrogen atom arises in 2-vinyloxypyridine and 2-vinylthiopyridine, which primarily exist in the s-trans-conformation, according to the ¹H and ¹³C NMR data. This interaction does not take place in 2-vinyloxymethyl- and 2-vinyloxyethylpyridines, which primarily exist in the s-cis-conformation. The C-H...N intramolecular interaction also does not occur in o-vinyloxyaniline due to the specific features of the stereoelectronic state of the amino group nitrogen atom.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1077–1081, August, 1991.     

Photodimers of 1-vinyl-2-pyridones; synthesis and study of the structure by the method of 1H and 13C NMR

The action of natural light on 1-vinyl-2-pyridone and a series of its substituted compounds gave the corresponding photodimers with the retention of the vinyl group. The steric and electronic structure of the substances obtained was studied by the method of ¹H and ¹³C NMR by comparison with the structure of the initial monomers. It was established that the stereoorientation of the vinyl group depends on the position of the substituent in the ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 942–946, July, 1990.     

Determination of the structure of 7-diethylamino-4-(1,2,3-triazol-1-yl)-2H-1-benzopyran-2-one derivatives using two-dimensional heteronuclear chemical-shift correlated NMR techniques

¹H and¹³C NMR spectra of 7-diethylamino-4-(1,2,3-triazol-1-yl)-2H-1-benzopyran-2-one derivatives have been studied. The location of the substituent in the 1,2,3-triazole ring was determined by the 2D COLOC method. It was established that the H(3) and H(5) protons in the coumarin moiety experience anisotropic influence of the phenyl subsituent at the C(5) atom in the triazole ring.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1330–1332, July, 1994.     

Structural examination of 1-vinylphenothiazine, 10-vinylphenothiazine S-oxide, 10-vinylcarbazole, 9-vinylcarbazole,and 9-vinyl-β-carboline by 1H and 13C NMR

According to ¹H and ¹³C NMR, the vinyl group in 10-vinylphenothiazine is coplanar with the plane orthogonal to the axis of the lone pair on nitrogen, as a result of bending of the ring along the S-N axis. In 10-vinylphenothiazine S-oxide, this bending does not occur, and as a result of the steric influence of the heterocycle the vinyl group is located nearly orthogonally to the heterocycle, and is analogous to the spatial structure of 10-vinylacridone. In 9-vinylcarbazole, the N-C torsion angle is 60°, increasing to 75° in 9-vinyl-1-methyl--carboline.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 408–415, March, 1992.     

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.     

13C NMR Study of the Structure of Vinyl Chloride-1-Vinyl-1,2,4-triazole Copolymer

The structure of the copolymer prepared by radical copolymerization of vinyl chloride with 1-vinyl-1,2,4-triazole was studied by quantitative ¹³C NMR spectroscopy. The structural unit of the copolymer consists of the units of vinyltriazole and quaternized vinyltriazole, vinyl group, and four vinyl chloride units.     

Pyrroles from ketoximes and acetylene

On the basis of a comparative study and analysis of the chemical shifts in the ¹³C NMR spectra of 1-vinyl-2-arylpyrroles and 3-alkyl-1-vinyl-2-phenylpyrroles, as well as 2-phenyl- and 1-ethyl-2-phenylpyrroles, it was established that the effects of substituents in the investigated series are transmitted via a mechanism involving conjugation and induction; the conductivity and polarizability of the 2-arylpyrrole system increase when a vinyl group is introduced in the 1 position or, in the case of the 1-vinylpyrrole system, when a phenyl group is introduced in the 2 position; this is due to the increase in the degree of overall conjugation.See [1] for communication IV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 768–772, June, 1978.     

Pyrroles from ketoximes and acetylene

The ¹³C NMR spectra of eight 2-alkyl- and 2,3-dialkyl-1-vinylpyrroles were studied. The ¹³C chemical shifts of all of the carbon atoms of the ring and the vinyl group depend substantially on the position and structure of the alkyl substituent. As the branched character of the alkyl group in the 2 position increases, the signal of the -carbon atom of the vinyl group is shifted to weak field due to weakening of the p- conjugation in the N-vinyl group because of disruption of its coplanarity with the pyrrole ring. The conjugation between the double bond and the pyrrole system involves competition for possession of the p electrons of the nitrogen atom.See [16] for communication II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 350–354, March, 1978.     

Conformational energy of the methy group at the C(5) atom in 1,3,2-oxazaborinates

The method of³H and¹³C NMR spectroscopy was utilized to determine the conformational energy of the methyl group at the C₍₅₎ atom in molecules of 2,3,5-substituted 1, 3, 2-oxazaborinanes. The resulting value of G⁰ (1 kcal/mole) is half the value of 1, 3, 2-dioxaborinanes and is close to the analogous value in tetrahydro-I, 3-oxazines (1.2 kcal/mole). The differences observed are associated with features of the p--electronic interactions in the heteroatomic fragment of the organoboron ring.     

Reactions of cis-2-Boryl-1-stannylalkenes with Carbodiimides, Thiocyanates, Isothiocyanates, and Isocyanates

The reactions of (E)-2-diethylboryl-1-trimethylstannylbut-1-ene and (Z)-3-diethylboryl-2-trimethylstannylpent-2-ene with carbodiimides, methyl thiocyanate, thioisocyanates, and isocyanates were studied, and the products were characterized by multinuclear magnetic resonance spectroscopy (¹H, ¹¹B, ¹³C and ¹¹⁹Sn NMR). It was found that carbodiimides bearing tert-butyl or trimethylsilyl groups at the nitrogen atoms do not react with (E)-2-boryl-1-stannylalkenes, in contrast to dicyclohexylcarbodiimide. There was also no reaction in the case of MeSCN. All other reactions proceed via a weak NB adduct formation in the initial step, followed by different rearrangements, depending on the structure of reagents as well as on the substitution pattern at the C=C bond in alkenes. New heterocycles are formed, in which the boron atom is either tricoordinated (1,2-azaborolenes, 1,2-azaborolan! es), a nd one ethyl group has been transferred to the neighbor olefinic carbon atom, or the boron atom is tetracoordinated (1,2-azaboratoles, 1,2-oxoniaboratoles), and the trimethylstannyl group has migrated to one of the heteroatoms of the heterocumulenes.