Cyclizaticn of 3-formyl-2-acetylenylindole oximes

Conclusions 3-Formyl-2-acetylenyl-1-methylindole oximes readily undergo intramolecular heterocyclization with closure of a pyridine ring and formation of substituted-carboline N-oxides.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2602–2604, November, 1984.     

The addition of diazomethane to β-ethynylpyridines

The action of diazomethane on -ethynylpyridines substituted in the pyridine ring or analogous compounds with an alkyl group in place of the acetylenic hydrogen atom has given 3-(pyridin-3-yl)pyrazoles. When the acetylenic hydrogen atom is replaced by an electron-accepting carboxyl group, the polarization of the triple bond interferes with the reaction, which then leads to a mixture of 3- and 4-(pyridin-3-yl)pyrazoles with the simultaneous methylation of the nitrogen of the pyrazole ring.     

Pot,atom and step economic synthesis of fused three heterocyclic ring compounds under microwave irradiation in water

A new series of fused three heterocyclic ring compounds, consisting of a pyrazolo (ring A), a pyridine (ring B), and a pyrimidine (ring C) core, pyrazolo[4′,3′:5,6]pyrido[2,3‐d]pyrimidine derivatives were successfully synthesized by pot, atom and step economic (PASE) method under microwave irradiation in the presence of p‐toluene sulphonic acid in water.     

(He 1) photoelectron spectra of vinyl- and (1-dimethylaminovinyl)pyridines

The (He 1) photoelectron spectra of -, -, -vinyl, -, -, and -(1-dimethylvinyl)-pyridines, 1-dimethyl- and 1-diethylaminostyrenes were obtained and interpreted within the framework of the molecular orbital perturbation theory. In both pyridine derivative series, there is a regular increase in the ionization energy of the 1a ₂, C=C and n_en orbitals and decrease in the ionization energy of the 2b₁ orbitals in the order < < (inversion of orbitals 1a ₂ and 2b₁ is found for -vinylpyridine). The splitting of the energy levels of the heterocycle in dimethylaminovinylpyridines is less than in the corresponding vinyl derivatives, which indicates a weakening of the interaction between the aromatic (or heteroaromatic) ring and the enamine fragment extruding from the ring plane. The ionization energy of the unshared electron pair of the nitrogen atom of the pyridine ring for all the compounds except for -(1-dimethylaminovinyl)pyridine (which displays an ortho effect) is close to that for pyridine. The photoelectron spectral data are compared with the MO energies calculated by the MINDO/3 method.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 103–108, January, 1985.     

Synthesis of new derivatives of thieno[2,3‐b]pyridine fused with octyl ring

Derivatives of thiophene, thieno[2,3‐b]pyridine, thieno[5′,4′:4,5]pyrimido[3,2‐a]pyridine and thiepine fused with octyl ring have been synthesized and tested for antimicrobial and antifungal activities. The structure of the newly synthesized compounds have been established on the basis of their analytical and spectral data.     

Peculiarities in the Fischer cyclization of 2,6-dichloro-4-pyridylhydrazones

The peculiarities of the Fischer cyclization of 2,6-dichloro-4-pyridylhydrazones were examined. It is shown that the introduction of chlorine atoms into the , position of the pyridine ring in all cases reduces the deactivating effect of the electron-acceptor pyridine nitrogen in this reaction and the Arbuzov modification (catalytic method). During thermal indolization, the process is shifted to favor the primary formation of 2,6-dichloro-4-aminopyridine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1638–1641, December, 1972.     

Regioselective and Regiospecific Cycloaddition of Acetylenes to 2,4,6-Triazidopyridine

The cycloaddition of tert-butylacetylene to 2,4,6-triazido-3,5-dicyanopyridine and 2,4,6-triazido-3-chloro-5-cyanopyridine occurs regioselectively and regiospecifically at the azide group in position 4 of the pyridine ring leading to the formation of the corresponding 4-(4'-tert-butyl-1H-1,2,3-triazolyl)pyridines as the sole products. Analogous reactions with the less sterically hindered n-butylacetylene are characterized by less regiospecificity and give a mixture of the isomeric 4'- and 5'-n-butyl-substituted triazoles at ratios of 96 : 4 and 91 : 9 respectively for the two different triazides. The interaction energies of the pyridine - and -azide groups with the acetylene molecules, and the energies of the transition states for these reactions have been calculated by the PM3 method. It was established that the high reactivity of the -azide group of the triazidopyridines in relation to the! ace tylenes is caused by the anomalously low distribution of bonding orbital density on these groups, leading to substantially lower activation energies in 1,3-dipolar cycloaddition reactions.     

Synthesis of New Imidazo[4,5-b]pyridine Derivatives

New imidazo[4,5-b]pyridine derivatives with various substituents in the 2-position (,-unsaturated ketones, imines, ²-pyrazolines, pyrimidines, 1,2,3,4-tetrahydropyrimidines) and derivatives of the new pyrido[3',2':4,5]imidazo[1,2-d][1,2,4]triazine ring system were synthesized. Biological data for selected compounds are presented.     

Crystal structure of N-(β-acetoxyethyl)-4-methylpyridinium bromide

In continuation of previous studies [1] on structures of compounds differing from acetylcholine and choline by having a pyridine ring instead of the quaternary N atom, the x-ray structure of N-(-acetoxyethyl)-4-methylpyridinium bromide, which has cholinergic activity [2], is solved.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1813–1816, August, 1991.     

Synthesis of fused tetracycles from the nitration products of benzo[b]thieno[2,3-c]pyridines

The nitration products of benzo[b]thieno[2,3-c]pyridines were used in the synthesis of new fused tetracyclic heterocyclic systems, which are structural analogs of natural ellipticine and olivicine alkaloids. Closure of the pyridine ring gives products only with linear ring fusion. This behavior was explained using the steric strain-stability principle and complete optimization of the structure of these products with a PCMODEL program and MMX force field in conjunction with the -electron approximation.L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 340114 Donetsk, Ukraine. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 406–411, March, 1997.     

Chemical peculiarities and structure of 2-(indane-1′, 3′-dionid-2′-yl)pyridinium (α-pyrophthalone)

The fine structure of 2-(indane-1,3-dionid-2-yl)pyridinium (-pyrophthalone) was determined by PMR spectroscopy and x-ray diffraction analysis. The -pyrophthalone molecule is almost planar; the dihedral angle between the pyridine ring and the indanedione ring is 5°. The structure is stabilized by an intramolecular hydrogen bond with a length of 2.73 Å. The molecules are packed in the crystal at van der Waals distances similar to those in molecular self-complexes. The data obtained for -pyrophthalone confirm a dipolar ion structure.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1076–1080, August, 1978.     

Der Einfluß von methyl- und dimethylsubstituierten Pyridinen als Liganden auf die Struktur und den Elektronentransfer bei Thiocyanat-Kupfer(II)-Komplexen

Complexes of the type Cu(NCS)₂ L ₂ whereL are all isomeric picolines and lutidines, as well as those of the type Cu(NCS)₂ L ₃ forL=-, -picoline, 3,4-, and 3,5-lutidine were prepared. The complexes were studied by means of thermal decomposition, and by electronic andESR spectroscopy. The results obtained have been brought into correlation with the effect of the ligandsL being caused by the methyl groups on the pyridine ring. It has been found that the differences in the properties studied which appear between Cu(NCS)₂ L ₂ and Cu(NCS)₂(pyridine)₂ are conditioned especially by the steric effect of the ligandsL with the methyl group in -position. The other ligandsL, however, show also an influence on some properties of the respective complexes.

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Mit 2 Abbildungen     

Facile preparation and the crystal structure of N,N′‐dialkyl‐2,6‐pyridinedimethanaminium halide

A facile preparation and the crystal structures of N, N′‐dialkyl‐2,6‐ pyridinedimethanaminium halides were described. Direct substitution reactions were convenient to prepare specifically secondary diamines using 2,6‐bis(chloromethyl)‐ pyridine and 10 equivalents molar of primary alkylamines. Hydrogen halide salts were obtained in good yields and the crystal structures of three N, N′‐dialkyl‐2,6‐pyridinedimethanaminium salts were determined by the X‐ray diffraction method. A cancroid structure around the pyridine ring was observed commonly in the three salts. Acidity constants of the three salts were determined. Since the pKa values of the salts were slightly smaller than those of several common triamines previously reported, the acidities did not correlate with the cancroid structure directly. This is probably due to electrostatic interaction of the two protonated amino groups, furthermore the central pyridine nitrogen was not protonated in all the ligands.     

Ready access to 7,8‐dihydro‐ and 1,2,3,4‐tetrahydro‐1,6‐naphthyridine‐5(6H)‐ones from simple pyridine precursors

Short pathways are described for the synthesis of a representative example of each of the 7,8‐dihydro‐and 1,2,3,4‐tetrahydro‐1,6‐naphthyridine‐5(6H)‐one ring systems from simple pyridine precursors. An attempted synthesis of the related 4,6‐dihydro‐1,6‐naphthyridin‐5(1H)‐one ring system from a common intermediate was unsuccessful.     

Versatility in inclusion hosts. Unusual conformation in the crystal structure of thep-t-butylcalix[8]arene: Pyridine (1:8) clathrate

Crystal structure analysis proves that thep-t-butylcalix[8]arene host sits around a symmetry center in thePI crystal lattice. The triclinic cell parameters and calculated volume are:a = 10.034(2),b = 17.434(2),c = 18.321(2) Å, = 113.86(1)°, = 93.08(1)°, = 92.62(1)°,V = 2919(2) ų. ForZ = 1 and F.W. = 1834.6 the calculated density is 1.04 g/cm³. It is shown that the host macrocycle is in an open chairlike conformation and virtually leaves no cavity to be occupied by the guest molecule. Consequently the pyridine guest molecules are enclathrated through steric barriers into the crystal lattice, having only one of the guests in the asymmetric unit bound to the host. The open conformation of the host is facilitated by a break in the ring of O-O hydrogen bonds on the rim of the would-be calix. This structure also conveys essential information on the possible solution conformations of the host in pyridine.     

Interaction of 1-tert-perfluorobutyl-3,3-di(perfluoromethyl)-2-aziridinone with weak nucleophiles

The title perfluoro--lactam (1) was found to react with N,N-dimethylformamide to give initially a betaine (2) which undergoes ring enlargement to produce the isomeric 2-dimethylamino-3,4,4-tri(perfluoroalkyl)substituted 5-oxazolidone (3). Related betaines were also obtained on reaction of1 with pyridine, quinoline, benzalaniline, andp-dimethylaminobenzaldehyde.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 372–374, February, 1993.     

Long-range13C—19F NMR spin-spin coupling in some α-trifluoromethyl-substituted polychloropyridines

High resolution¹³C NMR spectra of a series of -trifluoromethyl-substituted polychloropyridines were studied. Long-range¹³C—¹⁹F NMR spin-spin coupling through four and five bonds involving carbon atoms of the pyridine ring and the fluorine atom of the CF₃ group was found.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1973–1974, October, 1995.     

Der Einflu? von methyl- und dimethylsubstituierten Pyridinen als Liganden auf die Struktur und den Elektronentransfer bei Thiocyanat-Kupfer(II)-Komplexen

Complexes of the type Cu(NCS)₂ L ₂ whereL are all isomeric picolines and lutidines, as well as those of the type Cu(NCS)₂ L ₃ forL=-, -picoline, 3,4-, and 3,5-lutidine were prepared. The complexes were studied by means of thermal decomposition, and by electronic andESR spectroscopy. The results obtained have been brought into correlation with the effect of the ligandsL being caused by the methyl groups on the pyridine ring. It has been found that the differences in the properties studied which appear between Cu(NCS)₂ L ₂ and Cu(NCS)₂(pyridine)₂ are conditioned especially by the steric effect of the ligandsL with the methyl group in -position. The other ligandsL, however, show also an influence on some properties of the respective complexes.     

Evidence for the direct isomerization of a platinocyclobutane to an olefin complex

Dichloro-2,3,3-trimethyl-1-platinocyclobutane,

, prepared by the metathetical reaction of Zeise's dimer and 1,1,2-trimethylcyclopropane, reacts with pyridine in chloroform to produce a platinum complex of 2,3-dimethyl-1-butene

. Reaction of I with pyridine at low temperatures (ca. ?40° C) leads to a pyridine addition compound (III) in which the platinocyclobutane ring remains intact. The thermal isomerization of III, which may be conveniently studied using NMR, produces a mixture of II and the free olefin.     

The question of the oxidation of α-hydroxypyridine and nicotinic acid by Fenton's reagent

The oxidation of nicotinic acid and -hydroxypyridine by Fenton's reagent (H₂O₂ + Fe⁺⁺) takes place with the decomposition of the pyridine ring to form oxalic acid. In this process, half the label from the -hydroxypyridine passes into one of the oxygen atoms of the oxalic acid and the other oxygen atoms are derived from the hydrogen peroxide. The oxalic acid isolated from the oxidation of the nicotinic acid contains oxygen from the oxidizing agent. The results obtained show that the hydroxylation of the pyridine ring, apparently preceding its decomposition, takes place with the addition of an OH group containing oxygen from the oxidizing agent to the nucleus.