Studies of imidazo[1,2-a]benzimidazole derivatives. 21. Synthesis of haloketones in the imidazo[1,2-a] benzimidazole series

Methods for the synthesis of imidazo[1,2-a]benzimidazole haloketone derivatives have been investigated. It has been found that -bromoketone derivatives of this heterocycle can be prepared either by bromination of 3-acylimidazo[1,2-a]benz-imidazoles with bromine in glacial acetic acid or by acylation of 3-unsubstituted imidazo[1,2-a]benzimidazoles with haloanhydride derivatives of -bromoalkanoic acids. Treatment of imidazo[1,2-a]benzimidazoles with 3-chloropropionyl chloride results in the formation of imidazo[1,2-a]benzimidazolyl-3-propionyl chloride and bis(imidazo[1,2-a]benzimidazolyl)propan-3-one derivatives as side products. Reaction of 2-phenylimidazo[1,2-a]benzimidazoles with 3-bromopropionic acid in polyphosphoric acid gives benzocyclohepten[5,6:4,5]imidazo[1,2-a]benzimidazole derivatives.For Communication 20, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 339–345, March, 1986.     

Research on imidazo[1,2-a]benzimidazole derivatives. 25. Reaction of 2,9-disubstituted imidazo[1,2-a]benzimidazoles with acrylic acids and their derivatives

The substitutive addition of acrylic acids and their esters, amides, and nitriles to 2,9-disubstituted imidazo[1,2-a]benzimidazoles, which leads to 3-(imidazo[1,2-a]benzimidazol-3-yl)propionic acids and their derivatives, was studied. The rate of addition depends on the structure of the unsaturated compound, the nature of the substituent in the 2 position, the magnitude of the charge on the carbon atom in the 3 position of the heteroring, and the reaction conditions. The addition proceeds most smoothly in polyphosphoric acid (PPA). In the case of acrylonitrile imidazo[1,2-a]benzimidazol-3-ylpropionic acid amides were isolated in PPA. In the reaction of - or -substituted acrylic acids with 2-phenylimidazo[1,2-a]benzimidazoles in PPA, in addition to the corresponding imidazo[1,2-a]benzimidazol-3-ylpropionic acids, products of their intramolecular cyclodehydration at the ortho position of the phenyl substituent are formed.See [1] for Communication 24.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1496–1502, November, 1987.     

Homodimerization of spiro{bicyclo[2.2.1]Hepta-2,5-Diene-7,1′-cyclopropane}, catalyzed by group VIII transition metal complexes

Conclusions The homodimerization of spiro{bicyclo[2.2.1]hepta-2,5-diene-7,1-cyclopropane} (I) has been investigated in the presence of Ni-, Fe-, Co-, Rh-, and Ir-based metal complex catalysts. Depending on the nature of the metal and its ligand environment cyclodimerization of (I) can take place via [2+2]-, [2+2+2]-, and [4+4]-cycloaddition schemes, to give high yields of hepta-, octa-, and nonacyclic strained hydrocarbons.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2592–2599, November, 1988.     

Electronic structure, 1H NMR spectra,and reactivity in certain tricyclic heteroaromatic systems

The simple MO LCAO method was used for calculations on 4H-imidazo[5,1-b]benzimidazole, imidazo[5,1-b]benzoxazole, imidazo[5,1-b]benzothiazole, and a number of their derivatives. Inclusion of the unshared pairs of the hetero atoms at positions 4 and 9 in the -electron system has a considerable effect on the stability of compounds of this type. The ¹H NMR spectra were recorded for 4-methyl-imidazo[5,1-b]benzimidazole and imidazo[5,1-b]benzoxazole derivatives, and a similarity was found between the chemical shifts of the imidazole ring protons and the -electron densities at the adjacent carbon atoms. Calculation of a series of models for the cations and measurements of the basicity constants show protonation of 4-methylimidazo[5,1-b]benzimidazole takes place at the nitrogen atom in position 2. The calculated values for the electronic structure and reactivity indices in the investigated series of tricyclic systems were compared with their chemical properties.     

Electron structures of azoloisoindoles with a nodal nitrogen atom. 1. Derivatives of isoindolobenzimidazole and imidazo- and pyrazoloisoindoles

N-Methyl-substituted 1H-imidazo[2,1-a]isoindole, 5H-isoindolo[2,1-a]benzimidazole, and 3H-pyrazolo[5,1-a]isoindole were calculated by the PPP and CNDO/2 methods. On the basis of the canonical and localized MO it was concluded that the examined compounds can, to a first approximation, be regarded as 1,2-disubstituted iso-indoles, i.e., 10-electron systems. The calculated data are in good agreement with the experimental UV spectra and the chemical properties of the investigated compounds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 646–652, May, 1987.     

Research on 1-aza two-ring systems

Reduction of 5-[2-(methoxycarbonyl)ethyl]-1,3-dihydropyrrolizines with lithium aluminum hydride gave 5-(-hydroxypropyl)-1,2-dihydropyrrolizines (in 70–90% yields), which have intramolecular -hydrogen bonds in dilute solutions. The parameters of the -hydrogen bonds were determined in the IR spectra, and their enthalpies were found. The data obtained (_OH 95–99 cm^–1, –H 3.05 kJ·mole^–1) show that among compounds with an aliphatic hydroxyl group and a system of electrons, 5-(-hydroxypropyl)-1,2-dihydropyrrolizines have some of the strongest intramolecular -hydrogen bonds.See [1] for communication XVI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 359–363, March, 1978.     

Research on imidazo[1,2-a] benzimidazole derivatives

,-Unsaturated ketones of the imidazo[1,2-a]benztmidazole series were synthesized from 3-formyl- and 3-acetyl-substituted imidazo[1,2-a]benzimidazoles by crotonic condensation in the presence of alkaline catalysts. The ,-unsaturated ketones can also be obtained by direct acylation of 3-unsubstituted imidazo[1,2-a]benzimidazoles with the chlorides of unsaturated acids. The properties and pharmacological activity of the ketones obtained were studied.See [1] for communication XIII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1660–1665, December, 1976.     

Investigations in the imidazole series

Cyclization of 2--oxoalkylthio- and 2--oxoaralkylthiobenzimidazoles and the reaction of 2-mercaptobenzimidazoles with -halogenoketones in the absence of bases has given a number of derivatives of thiazolo[3, 2-a]benzimidazole, cyclopentenothiazolo[3, 2-a]benzimidazole, and tetrahydrobenzothiazolo[3, 2-a]benzimidazole.For part XXXVI, see [6].     

Ab initio SCF and CI study of the electronic spectrum of pyridine N-oxide

Configuration interaction (CI) studies of ground, n *, * * electronically excited states are reported for pyridine N-oxide. The transition energy to the lowest * excited ¹ B ₂ state is calculated at 4.35 eV, compared to the experimental spectrum range of 3.67–4.0 eV. This state lies below the lowest n * excited ¹ A ₂ state calculated at 4.81 eV above the ground state. The only experimentally reported triplet state at 2.92 eV above the ground state is predicted to be the ³ A ₁ (*) state. The calculated energy lies at 3.27 eV. Numerous other high-lying singlet states as well as the triplet states have also been calculated. The intramolecular charge transfer character of the ground and the excited states have been studied in terms of the calculated dipole moment and other physical properties.     

Derivatives of 2-mercapto-6-methyluracil

The reaction of the sodium salt of 2-mercapto-6-methyluracil with , -dibromoalkanes Br(CH₂)Br (n=1,4,5,6) has given the corresponding , -bis(4-hydroxy-6-methyl-2-pyrimidinylthio) alkanes. The reaction of the same salt with 1,2-dibromoethane gave 7-methyl-5-oxo-2,3,4,5-tetrahydrothiazolo[3,2-a]pyrimidine and 5-methyl-7-oxo-2,3,4,7-tetrahydrothiazolo[3,2-a]pyrimidine, and its reaction with 1,3-dibromopropane led to 8-methyl-6-oxo-3,4,5,6-tetrahydro-2H-pyrimidino[2,1-b]-1,3-thiazine.     

Formation of bromo-substituted imidazo[1,2-a]pyridines and their aza and thia analogs when the chichibabin reaction is carried out in dimethyl sulfoxide

The reactions of bromomethyl ketones with 2-aminopyridine, 2-aminopyrimidine, 2-aminothiazole, and 2-aminobenzothiazole in dimethyl sulfoxide lead to bromo-substituted (with respect to the position of the imadozole ring) imidazo[1,2-a] pyridines, imidazo[1,2-a]pyrimidines, imidazo[2,1-b]thiazoles, and imidazo[2,1-b]-benzothiazoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 258–262, February, 1978.     

Dimerization of biradicaloid heterocyclic compounds. Nitro derivatives of pyrrolo[1, 2-a]benzimidazole

A new type of easily dimerized heterocyclic compound, viz., nitro derivatives of 2-phenylpyrrolo[1,2-a]benzimidazole, was discovered. The reaction proceeds by heating the latter in acetic acid. A radical mechanism for the dimerization that takes into account partial protonation of the starting compound is discussed on the basis of electrochemical data, the high -donor capacity of 2-phenyl-4-methylpyrrolo[1,2-a]benzimidazole, the coloration that is characteristic for selfcomplexes, and EPR spectroscopy.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 188–196, February, 1984.     

Investigation of the electronic effect of the diphenylphosphino group

We have synthesized meta-substituted derivatives of benzoic acid, determined their ionization constants in water-alcohol solutions of concentration 11 and 14 by volume, and calculated the Hammett constant _m of the diphenylphosphino (0.12), diphenylamino (–0.04), diphenylphosphinyl (0.40) and diphenylthiophosphinyl (0.32) groups. Unlike the diphenylamine group, the diphenylphosphino group is metaorienting, which is probably to be explained by the absence or the weak nature of p- conjugation of incomplete electron pairs on the phosphorus and the presence of an electron-acceptor effect (d-p conjugation).     

New form of effective potential to calculate polarization effects of theπ-electronic states of organic molecules

A new relation for the contribution of the most important polarization effects in the energy of the -electronic states of organic molecules is derived. For -electronic systems we suggest a correct form of the ejfective potential of the two-panicle polarization interaction of -electrons via the polarizable -core. This form approximates (by the Thomas-Fernti method) the exact contribution of the corresponding exchange polarization diagrams of the Rayleigh-Schrödinger perturbation theory. The potential may be flectively used in ab initio calculations of -electronic systems typically done in the frozen core approximation.Hydrometeorological Institute, Ukraine. Translated fromZhurnal Strukturnoi Khimii, Vol. 34, No. 5, pp. 12–19, September–October, 1993.Translated by L. Smolina     

Cooligomerization of 1,2-dienes with norbornadienes catalyzed by cobalt complexes

Conclusions Under the action of low-valency cobalt complexes [2 + 2 + 2] cycloaddition of allene, cyclopropylallene, phenylallene, and 1,2-cyclononadiene to norbornadiene and spirocyclo-[2.2.l]hepta-2,5-diene-7,1-cyclopropane takes place with the formation of derivatives of tetracyclo[4.3.0.0^2,4. 1.0^3,7] nonane in high yields.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1346–1356, June, 1988.     

Research in the imidazole series

The synthesis of 9-acyl- and 8-alkyl-9-acyl-substituted naphth[1,24,5]imidazo[2,1-b]thiazoles was accomplished by the reaction of 2-acylmethylthionaphth[1,2-d]imidazole with acylating agents and of 2-mercaptonaphth[1,2-d]imidazole with 3-chloro-2,4-pentanedione.See [1] for communication LXVII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 30–32, January, 1972.     

Polynuclear heterocyclic compounds based on the adduct of o-cinnamoylbenzoic acid and cyclohexanone

The product of addition of cyclohexanone to o-cinnamoylbenzoic acid, which has the 4-phenyl-8a-hydroxyperhydrochroman-2-spiro-3-phthalide structure, reacts with nitrogen-containing nucleophiles to give hydrogenated derivatives of oxa-(aza, thia)indolizinespirophthalide and pyrido[1,21,2]imidazo[2,3-a]-isoin-dole, as well as 4-R-1-phthalazones. An isoindolo[1,2-a]quinoline derivative and a compound with a 7,8-diaza-D-homosteroid skeleton were obtained from the latter.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1280–1285, September, 1986.     

Study of the effects of conjugation in alkenyl derivatives of silicon and germanium by infrared spectroscopy

Conclusions The effects of d-p and, conjugation in the vinyl and allyl derivatives of silicon and germanium depend on the nature of the other three substituents.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2074–2076, September, 1971.     

The influence of solvation on π *←n and π *←π transition energies in molecules containing Aza or carbonyl groups

The influence of solvation on ^*n and ^* transition energies of formaldehyde, acetaldehyde, acetone, pyridine and 1,2-, 1,3-, 1,4-diazabenzenes has been investigated through CNDO calculations.A static solvation model which distinguishes a) molecules directly involved in hydrogen bonding with solute, b) the layer of molecules in contact with the solute molecule and c) the main of molecules farther from solute, is presented.Blue and red shifts due to solvent effects are correctly predicted by calculations for each model.     

Study of reaction of 2,3,3-trimethyl-3H-indole with haloacetic acid amides. Synthesis of 1,2,3,9a-tetrahydro-9H-imidazo[1,2-a]indol-2-ones

In the reaction of 2,3,3-trimethyl-3H-indole with -chloro- and -iodoacetamides, 1-carbamoylmethyl-2,3,3-trimethyl-3H-indolium salts are formed, which by the action of bases convert into imidazo[1,2-a]indol-2-one and 1-carbamoyl-2-methylene-2,3-dihydroindole. The latter compound can by cyclized into imidazo[1,2-a]indol-2-one by the action of acetic acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 933–935, July, 1985.