Acetals of lactams and amides. 44. Synthesis of derivatives of aminocyanopyridines from enamino amides and enamino nitriles

It has been established that in the reaction of a tertiary enamino amide with a primary amine a substantial influence is exerted by the basicity of the amine and the steric hindrance of its amino group. The secondary enamino amides obtained interact with the diethyl acetal of dimethylformamide to form enamino amides substituted at the amide nitrogen or 1-substituted pyramidin-4-ones, depending on the degree of steric hindrance of the NH group. Compounds of both these types, on being heated in an alkaline medium, are converted into derivatives of 4-amino-3-cyano-2-pyridone. An enamino dinitrile — -cyano--dimethylaminocrotonitrile — condenses with acetals of amides and lactams to form dienic diamines which can be converted into derivatives of 3-cyano-4-dimethylaminopyridine.For communication 43, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 646–649, May, 1985.     

Reaction of Β-oxonitrones — Imidazoline and pyrroline derivatives — With nucleophilic reagents

The reaction of -oxonitrones — imidazoline derivatives — with hydroxylamine, phenylhydrazine, and semicarbazide takes place at the carbonyl group with retention of the nitrone group. Stable nitroxyl radicals — spiroimidazoisoxazole derivatives — are formed in the oxidation of -hydroximinonitrones. The recyclization of the -oxonitrones, which takes place in an acidic medium, as well as by the action of hydrazine and thiosemicarbazide, leads, respectively, to pyrroline and pyrazole derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 912–919, July, 1991.     

Enthalpies of formation of methoxybenzoic acids and their dependence on structure

The energy of combustion of 2,5-dimethoxybenzoic acid has been determined using a static bomb calorimeter. The vapor pressures of the compound have been measured over a 18 K temperature interval by the Knudsen effusion technique. Heat capacity measurements betweenT=270 K andT=338 K were carried out by DSC. From these experimental results the standard molar enthalpies of combustion, sublimation, and formation in the crystalline and gaseous state at the temperature 298.15 K have been derived. With this compound, the series of mono- and dimethoxy-benzoic acids have been completed. Their_f H _m ^o values were expressed by an additive relationship, taking into account the number of methoxy groups and the number of all 1,2 interactions: an accuracy of 3.3 kJ·mol^–1 was achieved. In an alternative approach the substituent effect of the methoxy groups was evaluated within the framework of isodesmic reactions. The effect of disubstitution was referred to mono derivatives and the excess energy—the so-called buttressing effect—was evaluated (2–24 kJ· mol^–1 for individual bis derivatives). These values were explained in terms of the conformation of the methoxy group around the C_ar-O bond.     

New method of isolating N-substituted 3-aminomethylenethiol-4-en-2-ones

The methods for the synthesis of the little-studied N-substituted 3-aminomethylenethiol-4-en-2-ones (I) — thiophene analogs of aromatic o-hydroxyazomethines — are based on the application of the not readily accessible and labile hydroxy and methoxy derivatives of thiophene [1, 2].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 854–855, June, 1986.     

Substitution électrophile aromatique dans l'anhydride sulfureux liquide. Etude cinétique de la réaction de bromation d'anisoles monosubstitués. Transmission des effets électroniques et caractéristiques de l'état de transition

Reactivity-structure correlations for anisole and eleven of its substituted derivatives established from bromination rate constants in liquid SO₂, unlike observations in water, show the reaction to be highly sensitive to substituent effects, (ρ = ?7.1; ρ = ?10.51). This result is ascribed to the solvation of the methoxy group which decreases the conjugation of para-substituted (ρ = ?9.70) compared to that of ortho-substituted derivatives (ρ = ?8.86). The highly solvated transition state lies far from reactants on the reaction coordinate and the positive charge developed in this state is nearly unity.     

Research on 6- and 7-substituted 2-and 4-thioquinolones. Transmission of the electronic effects of substituents in the benzene ring of thioquinolones to the reaction center

The electronic effect of substituents on the acid-base properties of 6- and 7-substituted 2-thionolepidines and 4-thionoquinaldines were investigated. It is shown that the pK _a (–H⁺) values for 6- and 7-substituted 2- and 4-thioquinolones and the pK _a (+H⁺) values for 7-substituted 2-thionolepidines and 6-substituted 4-methylmercaptoquinaldines correlate with the _M substituent constants of Jaffe and Taft. The effect of a substituent is transmitted primarily via an inductive mechanism, regardless of its position.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 399–402, March, 1974.     

B—Z bond dissociation energies of <Emphasis Type="Italic">para</Emphasis>-substituted phenylboranes: a problem for Nau's definition of polar ground-state effects

UB3LYP/6-311++g(2df,p) and RMP2/6-311++g(d,p) methods were used to calculate B—Z bond dissociation energies (BDE) of para-substituted phenylboranes (X—C₆H₄—BH—Z). It was found that the slopes () of regressions between B—Z BDEs and substituent _p constants increase in the order B—Cl (between –0.24 and 0.21 kcal/mol) < B—H (0.06-0.33 kcal/mol) < B—F (0.48-0.78 kcal/mol) < B—CH₃ (0.83–1.28 kcal/mol) < B—Li (2.62-3.73 kcal/mol). Since all the homolysis reactions give the same boron radical, the large variation of indicates that the substituent effects on energies of the ground-state molecules are important for the substituent effects on BDEs. However, the ground-state stabilization energies, calculated using either Nau's method or our method, do not show any correlation with the polarization of the B—Z bond as defined by the electronegativity difference between the group X—C₆H₄—BH and Z. Therefore, the theory that the remote substituent effects on Y—Z BDEs are dependent on the Y—Z polarity should be discarded.     

Synthesis and properties of sym-triazine derivatives. 8. Synthesis of amino and alkoxy derivatives of sym-triazine containing fragments of a sterically-hindered phenol from 2,4-bis(trichloromethyl)-sym-triazines

The reactions of 2,4-bis(trichloromethyl)-6-substituted sym-triazines with several amino and hydroxy derivatives of 2,6-di-tert-butylphenol were studied. It is shown that, depending on the reaction conditions, one or both trichloromethyl groupings in the starting sym-triazines are replaced.See [1] for Communication 7.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 681–686, May, 1988.     

Transcyclization of benzoxazoles

The reaction of benzoxazoles with aromatic and aliphatic acids, which gives transcyclization products — 2-substituted benzoxazoles — was studied. The reaction of 2-hydroxyacetanilide with aliphatic acids gives a mixture of 2-substituted benzoxazoles. Under similar conditions, 2-methylbenzothiazole, 2-alkyl-²-oxazolines, and 2-alkyl-²-thiazolines do not undergo transcyclization, but ring opening is observed in the latter two cases.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1480–1482, November, 1972.     

AM1 study of photoelectronic spectra

Ionization energies of four model compounds with known conformations,i.e., benzo-1,3-dioxole, 2-methoxyphenol, benzo-1,3-dioxole-5-carbaldehyde (piperonal), and 4-hydroxy-3-methoxybenzaldehyde, have been calculated by theab initio AM1 method, using the formalized scheme of configuration interactions. It has been demonstrated that this method is adequate for the study of photoelectronic spectra of methoxy(hydroxy)-substituted benzenes. The ionization energies of 1,2-dimethoxybenzene, 3,4-dimethoxybenzaldehyde, and 4-hydroxy-3,5-dimethoxybenzaldehyde have been calculated for various orientations of theo-methoxy(hydroxy) groups. It has been revealed that three first ionization potentials corresponding to the states with vacancies on the -MO depend on the torsion angle. It has been established by comparison of calculated and experimental ionization potentials that in gas the compounds with adjacent methoxy groups have one O-Me bond parallel with the plane of the benzene ring, while another group is nearly perpendicular to this plane. Conformations of the heavy-atom framework are planar for gaseous molecules with adjacent methoxy and hydroxy groups.For Part 7, see Ref. 1.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2365–2368, December, 1995.     

Mass spectrometric study of 4-azafluorenes

The dissociative ionization of 4-azafluorene and its methyl and phenyl derivatives was investigated. The relative intensity of the [M — CH₃]⁺ ion peak depends on the position of the CH₃ group in the 4-azafluorene ring. It was established that the loss of an RCN particle (R=H, CH₃, and C₆H₅) for unsubstituted 4-azafluorene takes place from the M⁺ and [M — H]⁺ ion, exclusively from the [M — H]⁺ ion for the methyl-substituted compounds, and from the [M — H]⁺ and [H — 2H]⁺ fragments for the phenyl-substituted derivatives. Randomization of the deuterium ions in the 9,9-d₂-4-azafluorene molecular ion was observed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 246–250, February, 1978.     

Synthesis and spectroluminescent properties of 4-oxo-1,2,3,3a-tetrahydropyrimido[1,2,3-Z,m]-α-carbolines

The reaction of 1-acetyl-2-arylpyrazolidines with the DMF-POCl₃ complex and subsequent treatment of the iminium salts formed with the potassium enolates of -substituted acetate esters yielded a series of previously unknown -carboline derivatives. The spectroluminescent properties of these compounds were studied. Some of the -carbolines synthesized have a laser effect.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 82–83, January, 1985.     

Reaction of C19-diterpene alkaloids with sodium in liquid ammonia

The reaction of C₁₉-diterpene alkaloids with sodium and liquid ammonia in the presence and in the absence of a proton donor — an alcohol — has been investigated. In the absence of the proton donor the hydroxy group is converted into a carbonyl group, which is characteristic only for C-6-hydroxy or -acetoxy derivatives.Abu Ali Ibn Sina [Avicenna] Tadzhik State Medical Institute, Dushanbe. Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 372–375, May–June, 1989.     

Synthesis of some new arylindoles

New indole derivatives — 2-ethoxycarbonyl-5(p-acetylphenyl)indole andpara-substituted 2-diphenylindoles —key compounds for synthesis of new bisindoles, were synthesized from 4-acetyl-4-nitrodiphenyl.I. Dzhavakhishvili Tbilisi State University, Tbilisi 380028. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1351–1354, October, 1994. Original article submitted September 15, 1994.     

Investigation of nitrogen- and sulfur-containing heterocycles

A number of derivatives of a new heterocyclic system — pyrimido[5,4-b][1,4]-7-oxazinone- were obtained by the reaction of substituted 5-hydroxy-6-aminopyrimidines with ethyl esters of-halocarboxylic acids.See [1] for communication XXIII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1285–1288, September, 1972.     

Condensed isoquinolines. 9. Alkylation of 7,12-dihydro-5H-isoquino[2,3-a]quinazolin-5-ones

The alkylation of 7,12-dihydro-5H-isoquino[2,3-a]quinazolin-5-one proceeds at N₍₆₎ or C_(–) depending on the type of alkylating agent and reaction conditions. C_(–)-Alkylation occurs in the presence of base. The secondary alkylation of the 7-alkyl derivatives occurs at the same position under these conditions. Depending on the conditions, the reaction with o-xylylene dibromide leads to spiro[5H-isoquino[2,3-a]quinazolin-7(12H).2-indane]-5-one or 11-oxo-4b,5,10,16-tetrahydro-11H-10a-azonia-15b-azadibenz[a,e]pleiadene bromide, which are derivatives of new heterocyclic systems.Communication 8, see ref. [1].See also Letter to Editor [2].Taras Shevchenko Kiev University, 252017 Kiev, Ukraine. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 643–652, May, 2000.     

The structure of karakolidine

Summary As the result of a study of chemical transformations and spectral characteristics, for the new alkaloid karakolidine a lycoctonine skeleton with N-ethyl and C₄-methyl groups, hydroxy groups at C₁ (), C₈, C₁₀ (), and C₁₃, and a methoxy group at C₁₅ () has been established.Some peculiarities of the fragmentation of derivatives of karakoline and karakolidine under the action of electron impact have been found.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 481–486, July–August, 1975.     

Synthesis of β-(9-purinyl)alanines

The corresponding 1-(6-substituted-9-purinyl)-2,2-diethoxyethanes were obtained by alkylation of 6-substituted purines with 1-bromo-2,2-diethoxyethane. Subsequent transformations of a large portion of the acetals gave 2-(6-substituted-9-purinyl) acetaldehydes, from which -(6-substituted-9-purinyl)alanines were obtained by the cyanohydrin synthesis. The classification of the compounds as N(₉)-substituted purine derivatives was proved by means of UV spectroscopy.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1561–1566, November, 1972.     

Investigation of nitrogen- and sulfur-containing heterocycles

The synthesis of two-ring 1,4-thiazine systems was previously accomplished on the basis of the reaction of o-amino mercapto derivatives of pyridine and pyrimidine with dicarbonyl compounds — halo -keto esters and halo -diketones. In the present paper it is shown that the primary products of this reaction are S--keto-alkylmercapto derivatives, which are subsequently cyclized to the corresponding hydroxy amino compounds. The latter are converted to N-acylamino-S--carbethoxy (keto)alkylmercapto derivatives under the influence of an alkaline agent. The indicated compounds were isolated and characterized [2, 3].See [1] for communication 36.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 250–253, February, 1979.     

Reaction of 2-substituted 5,5-dimethyl-4-oxo-1-pyrroline-1-oxides with nucleophilic reagents and synthesis of nitroxyl radicals—derivatives of pyrrolidine

The reaction of -oxonitrones, derivatives of pyrroline, with nitrogeneous nucleophiles and NaBH₄ proceeds at the carbonyl group with the retention of the nitrone group. The reaction with organomagnesium and organolithium compounds takes place at the nitrone group with the retention of the carbonyl group, while the oxidation of the products formed proceeds to form nitroxyl radicals—Derivatives of pyrrolidin-4-one, which were used in the synthesis of spin-labeled dioximes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 390–395, February, 1990.