Optically active N-(α-phenylethyl) amides of isomeric 1-phenylpyrazolecarboxylic acids

The rotatory dispersion of the (–)-N-(-phenylethyl)amides of the isomeric 1-phenylpyrazolecarboxylic acids depends on the position of the amido group in the pyrazole ring. The difference in the spectropolarimetric behavior of the isomers can be used to determine the position of a substituent in the pyrazole ring. The phenylpyrazole group induces a pronounced Cotton effect in the region of its absorption if there is conjugation between the benzene and pyrazole rings. The analogy in the spectropolarimetric behavior of the (–)-N-(-phenylethyl)amides of 1-phenylpyrazole-4-carboxylic and benzoic acids attests to the aromatic character of the 4 position in the pyrazole ring, which is also well known from its chemical properties.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1569–1572, November, 1970.     

Structure and half-wave potential in anils of araldehydes

Substituent effects are considered, and it is shown that a given substituent has effects on the activity of the-CH=N- group dependent on the benzene ring to which it is attached. An electron-donor substituent shifts E_l/2 towards the negative side if it is introduced into the p position of the aniline phenyl group, because a substituent in that position has two forms of conjugation: with the double-bond electrons and with the electron pair on the N atom. A substituent in the same position in the benzylidene part does not have the latter form of conjugation and does not alter the molecular geometry, so it has less effect on E_1/2 for the-CH=N- group.     

Saturated nitrogen-containing heterocycles. 16. Catalytic synthesis of N-arylperhydroacridines

Catalytic hydroamination of methylene-2,2-dicyclohexanone in the presence of substituted anilines or nitrobenzenes involves the formation of N-arylperhydroacridines. The stereoisomeric composition and yields of the latter are determined by the nature and position of the substituent in the aromatic ring of the aminating agent. The structure of isomeric N-arylperhydroacridines was established from data of ¹³C NMR spectroscopy and x-ray diffraction analysis.For Communication 15, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1094–1100, August, 1993.     

Mass spectra of substituted 4-aminopiperidines with a shielded nitrogen atom

The principal fragmentation pathway of 4-aminopiperidines under the influence of electron impact are determined by charge localization on the nitrogen atom of the piperidine ring or on the nitrogen atom of the substituent in the 4 position. In the case of electron-donor substituents in the 4 position and in the absence of a substituent attached to the nitrogen atom of the polysubstituted piperidine ring the charge is primarily localized on the nitrogen atom of the substituent; this is expressed in the specific fragmentation pathways. The principles found in this research make it possible to establish the structures of nitrogen-containing compounds that are similar to the investigated compounds.Communication 10 in the series Application of mass spectrometry in structural and stereochemical studies. See [1] for Communication 9.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 72–77, January, 1981.     

Research on the chemistry of 2-hetarylbenzimidazoles

The condensation of 1-methyl-2-formylpyrrole with o-phenylenediamine gave 2-(1-methyl-2-pyrrolyl)benzimidazole, which was subjected to methylation. The alkylation product was subjected to electrophilic substitution. The substituent is incorporated in the 4 or 5 position of the hetaryl ring; however, bromination of 1-methyl-2-(1-methyl-2-pyrrolyl)benzimidazole leads to the formation of the mono-, di-, and tribromo derivatives, depending on the conditions. The acidophobic properties of the pyrrole ring are partially lost as a consequence of the effect of the benzimidazole ring.See [1] for Communication 1.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 71–73, January, 1980.     

Intramolecular rearrangement of N-alkyl-2-thio-2-(2′-chloroalkoxy)-1,3,2-azaoxaphosphorinanes

Conclusions The structure of the rearrangement products of the N-alkyI-2-thio-2-(2-chloroalkoxy)-1,3,2-azaoxaphosphorinanes depends on the substituent in the chloroalkoxyl group and the ring substituent in the 4 position.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2107–2110, September, 1976.     

Reaction of methiodides of 1,2,3,4-tetrahydro-γ-carbolines with nucleophilic agents

It is shown that C, N, and O nucleophiles smoothly cleave the hydrogenated ring of quaternized tetrahydro--carbolines to give isotryptamine derivatives with a CH₂Z substituent in the 3 position (Z = Me, Ph, CN, OEt, piperidino, and morpholino). The principles of the mass-spectral fragmentation of the synthesized compounds as a function of the character of the substituent attached to the methylene group in the 3 position were established.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1072–1078, August, 1981.     

Triple Equilibrium in N'-Aryl-N-tosyldiazomalonimidolates, 1-Tosyl-1,2,3-triazol-5-olates, and 1-Aryl-1,2,3-triazol-5-olates

A series of 1-tosyl-substituted 4-arylcarbamoyl-1,2,3-triazol-2-olates, which can undergo rearrangement to isomeric 1-aryl-4-tosylcarbamoyl-1,2,3-triazol-5-olates and N-tosyl-N'-aryldiazomalonimidolates, were synthesized. An equilibrium between these compounds is observed in solutions in DMSO. The introduction of an electron-withdrawing substituent into the aryl residue increases the stability of the 1-tosyl-1,2,3-triazoles but reduces the stability of the 1-aryl-1,2,3-triazoles. -Donating substituents increase the stability of the open-chain structure.     

Transmission of inductive effect and polar resonance effect through the benzene and the furan ring in PMR spectra

Assuming the independence and additivity of the inductive and polar resonance effects, experimental data for chemical shifts in proton magnetic resonance (PMR) spectra of mono and disubstituted benzene and furan derivatives are used to calculate transmission coefficients for the inductive and polar resonance effects due to any substituent for a proton in the 2, 3, or 4 position in the ring. Values of ^* and ^c are tabulated. With benzene compounds transmission of the polar resonance effect decreases on passing from the p and o to the m position. The coefficient of transmission of the inductive effect to a proton in the m or p position is negligible.With furan compounds the values of the coefficient ^c for 2, 5 and 2,4 ring positions are close to the corresponding values for benzene compounds. In the furan ring a considerable part of the polar resonance is transmitted through the heteroatom. The ^* coefficients are appreciably greater with furan than with benzene compounds, because the ring carbon atoms screen the proton less from the substituent. Most of the inductive effect from the 2 to the 5 position in the furan ring is direct (transmitted through space).     

Synthesis and spectral properties of shielded 1,2-disubstituted imidazolines

Shielded 1,2-disubstituted imidazolines were synthesized by condensation of diethylenetriamine with 2-ethylhexanoic acid. UV, IR and¹H and¹³C NMR spectral data were discussed. The effect was studied of branching in an alkyl substituent at the 2 position of the imidazoline ring on the spectral parameters of the synthesized compounds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 878–882, April, 1991.     

σ-Complexes in the pyrimidine series. 13. Reaction of 7- and 5-methoxyfuroxano-[3,4-d]pyrimidines with some C-nucleophiles

We have studied the reaction of isomeric 7-and 5-methoxyfuroxano[3,4-d]pyrimidines with carbanions of some CH acids. We have shown that regardless of the position of the substituent in the pyrimidine ring, nucleophilic attack occurs regioselectively at the C₍₇₎ atom. As a result, we have obtained the products of substitution at the methoxy group, and also anionic complexes and covalent adducts.For Communication 12 see [1].Institute of Bioorganic Chemistry and Petrochemistry, National Academy of Sciences of Ukraine, Kiev 253660. Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 34, No. 1, pp. 112–119, January, 1998.     

Photochemistry of 2-amino-2H-benzochromenes

Diabatic photoinduced ring opening of the chromene ring of 2-amino-5,6-benzo-2H-chromenes and 2-amino-6-methyl-7,8-benzo-2H-chromenes leads, in the same way as a thermally induced reaction, to the establishment of ring-chain tautomer equilibrium in the ground electronic state, the position of this equilibrium depending on the polarity of the solvent, the temperature, and structural factors. o-Quinoid tautomers exist as several stable isomeric forms: an acoplanar cis-S-cis-trans-form absorbing in the shortwave region, and S-trans-isomers absorbing in the longwave region of the spectrum. Photoexcitation of the o-quinoid forms in the temperature range 125–190 K initiates mutual conversions of these and the initial 2H-chromene structure. The relative stability of the conformers of the o-quinoid form depends on steric and electronic factors: benzanellation in positions 5,6 leads to stabilization of the cis-S-cis-trans-isomer and in positions 7,8 the S-trans-isomers are more preferred: -acceptor substituents on the amine component increase the stability of the cis-S-cis-trans isomer and electron-donor substituents stabilize the S-trans-isomer.Communication 20 from the series Photo- and thermochromic piranes. See [1] for Communication 19.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 453–458, April, 1991.     

Electrochemical oxidation of 3-imidazoline 3-oxides

Cyclic voltammetry was used to study the electrochemical oxidation of substituted 3-imidazoline 3-oxides. It was determined that the oxidation potentials (E _p/2) of the compounds depend on the nature of the substituents in the 1 and 4 positions of the ring. A correlation analysis ofE _p/2 of the the compounds and _I and _R of the substituent constants in the 4 position of the ring was carried out. The obtained results show that oxidation of 3-imidazoline 3-oxides can occur at the nitrone or amine fragment, depending on the nature of the substituent in the 1 position of the ring.Institute of Organic Chemistry, Russian Academy of Sciences, 630090 Novosibirsk. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2545–2550, November, 1992.     

Investigation of 2,5-disubstituted silylfurans by PMR spectroscopy

The¹H,¹³C, and²⁹Si NMR spectra of S-substituted furfurals and the corresponding diethyl acetals containing various alkylsilyl substituents at position S of the furan ring were studied in comparison with the carbon- and sulfur-containing analogs and also with a series of monosubstituted silylfurans. In cases where the substituent was conjugated with the residue of the furan molecule the effect of the substituent at position S of the furan was transmitted to C of the aldehyde group. The reverse effect was also observed. It was determined that the contribution from the aldehyde group and the substituents at position S of the furan to the screening of the carbon nuclei of the furan ring was not additive.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 449457, April, 1996.     

3-(4-Thiocarbamoyl-1,2,3-triazol-1-yl)benzo-15-crown-5: synthesis and properties

A reaction of 1,2,3-thiadiazole-4-carbaldehyde with 3-aminobenzo-15-crown-5 involves the Cornforth rearrangement of the 1,2,3-thiadiazole ring, which leads to 1,2,3-triazole-4-carbothioamide containing the benzocrown ether substituent in position 1 of the triazole ring. Reversible formation of the isomeric thiadiazole occurs in aprotic nonpolar solvents such as deuterated chloroform. These compounds are suitable for extraction of α-amino acids from an aqueous phase.     

Synthesis of new <Emphasis Type="Italic">N</Emphasis>-(pyridin-3-ylmethyl)-2-aminothiazoline derivatives possessing anticholinesterase and antiradical activity as potential multifunctional agents for the treatment of neurodegenerative diseases

New N-(pyridin-3-ylmethyl)-2-aminothiazolines containing various substituents at the 5 position of the thiazoline ring and the 4-tert-butylbenzyl, 4-isopropylbenzyl, or 4-fluorobenzyl moiety at the nitrogen atom of the amino group were synthesized. The inhibitory activity of the synthesized compounds against human erythrocyte acetylcholinesterase (AChE, EC 3.1.1.7), equine serum butyrylcholinesterase (BChE, EC 3.1.1.8), and porcine liver carboxylesterase (CaE, EC 3.1.1.1) was evaluated and their antioxidant properties were studied by ABTS assay. N-(Pyridin-3-ylmethyl)-2-aminothiazolines proveded to be very weak AChE inhibitors, while their inhibitory activity against BChE and CaE was structure-dependent. 2-Aminothiazolines containing the 4-tert-butylbenzyl moiety are more efficient BChE inhibitors compared to the derivatives containing the 4-isopropylbenzyl or 4-fluorobenzyl substituent. An analysis of the dependence of the esterase profile of N-(pyridin-3-ylmethyl)-2-aminothiazolines on the structure of the substituent at the 5 position of the thiazoline ring of these compounds demonstrated that the derivatives containing the iodomethyl substituent possess the highest anti-BChE activity, the compounds with R² = H and R³ = CH₂I have the optimal esterase profile. Regardless of the structure of the substituents in the benzyl moiety, all N-(pyridin-3-ylmethyl)-2-aminothiazolines containing the iodomethyl substituent at the 5 position of the thiazoline ring exhibited high radical scavenging activity comparable with that of the standard antioxidant Trolox. N-(Pyridin-3-ylmethyl)-2-aminothiazolines were shown to be a new promising class of compounds for the design of multifunctional agents for the treatment of neurodegenerative diseases.     

Research on the chemistry of 2-hetarylbenzimidazole. 3. Reaction of 1-methyl-2-(5′-methyl-2′-hetaryl) benzimidazoles with electrophilic reagents

A number of new derivatives of 1-methyl-2-(5-methyl-2-hetaryl)benzimidazole were synthesized by electrophilic substitution. The substituent enters the position of the 4-hetaryl ring. A furan ring that contains a methyl group in the 5 position undergoes profound destructive oxidation under the influence of acetyl nitrate. Depending on the conditions, bromination leads to the formation of bromo derivatives that are substituted in the benzene or hetaryl ring.See [7] for Communication 2.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 520–523, April, 1981.     

Investigation of perinone compounds

The electronic nature of the substituent in naphthalic anhydride has a substantial effect on the isomeric composition of the naphthaloperinones formed in reactions with 1,8-naphthylenediamine. An electron-accepting substituent in the 4 position of naphthalic anhydride promotes predominant retention of the carbonyl group in the 1 position, while an electrondonating substituent promotes retention of the carbonyl group in the 8 position of the naphthalene ring. 10-Amino- and 11-amino-14H-benzo[4,5]isoquinolino[2,1-a]perimidin-14-ones were synthesized.For Communication II see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1420–1422, October, 1970.     

Quantitation of isomeric ethyl pyridine mixtures by multivariate calibration applied to ion-molecule reaction/collision-induced dissociation triple-stage mass spectra

In reactions of the distonic ion ⁺CH₂OCH₂ with the three isomeric ethyl pyridines, ionized methylene transfer occurs readily yielding distonic N-methylene-ethylpyridinium ions. On-line mass selection and 10 eV collision-induced dissociation (CID) of the CH₂⁺ transfer products yields characteristic fragment ions, which are formed via processes greatly influenced by the ortho, meta or para location of the ethyl substituent in the pyridine ring. Quantitation of mixtures of isomeric 2-, 3-, and 4-ethyl pyridines of varying compositions was then performed by multivariate calibration in the form of the partial least square (PLS) model applied to both single-stage (MS) 70 eV electron ionization (EI) and pentaquadrupole triple-stage sequential ion-molecule reaction/CID product ion mass spectra. The results exemplify the superior ability of combined chemometric analysis and sequential mass spectrometric techniques, which benefits from both characteristic ion chemical reactivity and dissociation behavior, for rapid and accurate quantitation of complex isomeric mixtures.     

Stereochemistry of heterocycles

A number of previously undescribed alkyl-1,3,2-dioxaborinanes were synthesized by condensation of substituted 1,3-diols with alkylboron dichlorides or dibutyl isopropylborate. It was shown by PMR spectroscopy that the 2,5-dialkyl-1,3,2-dioxaborinane molecules are conformationally homogeneous and do not contain an axial substituent in the 5 position, whereas the 2-isopropyl-5,5-dimethyl-1,3,2-dioxaborinane molecules exist in a state of rapid ring inversion, and introduction of methyl substituents in the 4, 4, and 6 positions of the 1,3,2-dioxaborinane ring leads to distortion of the ring conformation and conformational heterogeneity of the investigated sample. The observed regularities are explained from the position of intensive oxygen-boron electron exchange in the heteroring. It is concluded that the 2,5-dialkyl-1,3,2-dioxaborinane molecules have primarily a conformation with a semiplanar form.See [1] for communication XLVIII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp, 26–30, January, 1978