Synthesis and properties of ethyl esters of some 1,2-dihydropyridine-3,5-dicarboxylic acids

The oxidation of diethyl 1-methyl- or 1-aryl-2,6-dimethyl-4-aryl-1,4-dihydropyridine-3,5-dicarboxylates with hydrogen peroxide in the presence of perchloric acid gave the perchlorates of the corresponding pyridinium ions, the reduction of which with NaBH₄ is a preparative method for the synthesis of diethyl esters of 1-substituted 2,6-dimethyl-1,2-dihydropyridine-3,5-dicarboxylic acids. Derivatives of the 5-carboxylic acid of the corresponding 1,2-dihydropyridine are formed by alkaline hydrolysis of these esters.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1225–1228, September, 1982.     

Mass spectrometric study of 2-azafluorenes

The fragmentation of 2-azafluorene and its methyl and phenyl-substituted derivatives was studied. It is shown that ejection of an RCN fragment (R=CH₃, C₆H₅) by the molecular ions leads to a more intense peak if R is in the 3 position of the azafluorene ring. It was established that, in contrast to the dissociative ionization of fluorene, all of the ions of which are formed from the (M-H)⁺ fragment, the fragmentation of 2-azafluorene and its derivative also takes place from the molecular ion. Randomization of the deuterium atoms attached to C₉ with the remaining hydrogen atoms was observed.Translated from Khimiya Geterotisiklicheskikh Soedinenii, No. 1, pp. 101–105, January, 1977.     

Complexes of diethylboric esters of alkanenitronic acids with pyridine

Conclusions When the diethylboric esters of alkanenitronic acids of general formula RR'C=NOOBEt₂ (R=H or alkyl, and R'=alkyl or COOCH₃) are treated with pyridine the intramolecular coordination bond is cleaved to give the complexes of diethylboric esters of alkanenitronic acids with pyridine.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1172–1174, May, 1978.     

Synthesis and reduction of derivatives of aziridinemono- and-dicarboxylic acids

Amides and esters of aziridine-2-carboxylic acid were synthesized by the reaction of 1,1,1-trimethyl-2-(2-carboxyethyl)hydrazinium derivatives with an anion-exchange resin or with sodium hydride. Enamines were obtained from 1,1,1-trimethyl-2-[1,2-bis(alkoxycarbonyl)ethyl]hydrazinium salts and basic agents. Methods for the synthesis of amides of aziridine-2,2- and aziridine-2,3-dicarboxylic acids were developed. The stereochemistry of the esters and amides of aziridine-2,3-dicarboxylic acids was established. Dialkylcarbamoylaziridines were reduced with lithium aluminum hydride to 2-(N,N-dialkylaminomethyl)aziridines. The reduction of esters of aziridine-2-carboxylic acid and their functionally substituted derivatives leads to the formation of 2-hydroxymethylaziridines. An O-silylation product was obtained by silylation of 2-hydroxymethylaziridine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1227–1235, September, 1983.     

Chlorination of tetrahydrofuran-2-carboxylic acid esters

The photochemical chlorinatlon of tetrahydrofuran-2-carboxylic acid esters with chlorine at –15 to –20C leads primarily to the formation of 5-chlorotetrahydrofuran-2-carboxylic acid esters (70–80%). 4,5-Dihydrofuran-2-carboxylic acid and furan-2- carboxylic acid esters are formed as side products. The structures of the principal and side products were investigated by PMR and mass spectroscopy.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 166–168, February, 1979.     

Studies on the series of azoles and azines. 65. Mass spectra of 5-arylidene-, 5-ethoxycarbonylmethylene-hydantoins and their derivatives

The mass spectra of 5-m- and p-substituted benzylidenehydantoins, their thio analogs and 5-carbethoxymethylenehydantoins with a substituent at the -carbon atom of the side chain were studied. The fragmentation of the molecular ions of 5-arylidenehydantoins proceeds in one direction, splitting of the X=C-NR-C=O fragment, irrespective of the substituent in the benzene ring. The peak intensity of the fragmentary ions formed from the molecular ions is linearly dependent on the -constants of the substituent. The direction of the fragmentation of 5-ethoxycarbonylmethylenehydantoins markedly depends on the substituent at the -carbon atom in the side chain that determines the stability of the hydantoin ring and the carboethoxyl group. The fragmentation of these compounds under electron impact proceeds by five paths, related to splitting of fragments O=C₍₂₎NCH₍₄₎=O, C₂H₄, C₂H₅O, C₂H₅OH, and COOC₂H₅.See [1] for Communication 64.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 625–631, May, 1988.     

Mössbauer effect studies on sodium hexa/carboxylato/ ferrates/III/

Mössbauer spectra of a series of the complexes of the type Na₃[Fe/RCOO/₆]xH₂O /R=H, CH₃, C₂H₅, C₆H₅/ has been recorded at 298±2 K. All display a quadrupole doublet with isomer shift and quadrupole splitting values in agreement with high spin iron/III/ octahedral geometry. The quadrupole splitting show an increasing trend with increasing polarizability of the substituent anion /RCOO^–/. A linear correlation between quadrupole splitting values and the /Fe–O/ stretching frequencies has also been observed.     

Synthesis and lactonization of 1-(2-hydroxy-1,1-dimethylethyl)-aziridine-2-carboxylic acid esters

The reaction of 2,3-dibromopropanoates with 2-amino-2-methyl-1-propanol in the presence of triethylamine gave a number of 1-(2-hydroxy-1,1-dimethylethyl)aziridine-2-carboxylic acid esters, which, under the influence of basic catalysts, were converted to a bicyclic lactone — 2,2-dimethyl-4-oxa-1-azabicyclo[4.1.0]heptan-5-one. The effect of the structure of the substrate and the nature of the lactonizing agent on the rate of cyclization was studied. Two new catalysts for the cyclization of hydroxy esters to lactones, viz., CsF/Al₂O₃ and Cs₂CO₃/18-crown-6, are proposed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1340–1343, October, 1988.     

Synthesis and separation of diastereomers of thiomorpholine-carboxylic acid esters

It is shown that the reaction of methyl 2,3-dibromopropionate with aminoethanethiol and L-cysteine methyl ester leads to the formation of esters of thiomorpholine-3-carboxylic and thiomorpholine-3,5-dicarboxylic acids; the latter ester was separated into individual diastereomers.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1357–1358, October, 1983.     

Spectroscopic and quantum-chemical study of 5-alkoxypyridine-2- and 6-alkoxypyridine-3-carboxylic acids

The peculiarities of the structures of 5-alkoxypyridine-2- and 6-alkoxypyridine-3-carboxylic acids were studyed by experimental (IR, UV, and PMR spectroscopy) and quantum-chemical methods. It was established that both types of compounds exist in the form of dimers in the crystalline state, whereas in CC1₄, the first type exist in the form of monomers, while the second type exist in the form of dimers and monomers in dynamic equilibrium. The ability to form an intramolecular hydrogen bond and the interaction of the unshared pairs of electrons of the ring nitrogen atom and the oxygen atom of the C=0 group are among the reasons for the absence of liquid-crystal properties in 5-alkoxypyridine-2-carboxylic acids as compared with 6-alkoxypyridine-3-carboxylic acids, which have such properties. From the point of view of the electronic structures, 6-alkoxypyridine-3-carboxylic acids differ from 5-alkoxypyridine-2-carboxylic acids in that in the former the ring nitrogen atom and the COOH and OAlk groups have an identical effect on the sign of the -electron charges of the ring carbon atoms, and their -dipole moments are directed virtually along the longitudinal axis of the molecule.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 228–234, February, 1978.     

Octaorganylsilasesquioxanes with chloromethyl substituents at the silicon atom

The combined heterofunctional hydrolytic polycondensation of organyltriethoxysilanes with chloromethyltrichlorosilane gives chloromethyl derivatives of octaorganylsilasesquioxanes, (ClCH₂)_n(R)_8–n[SiO_1.5]₈, where R=CH₃, C₂H₃, and C₂H₅. The dissociative ionization of these products occurs through a pathway different from that for the fragmentation of R- T₈ with hydrocarbon substituants at the silicon atom.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 441–445, February, 1990.     

Reaction of α,α,ω-trichloro- and α,α,α,ω-tetrachloroalkanes with alkali metal acylates in aprotic solvents

Polychloroalkanes and -alkenes R(CH₂)_nCl (R=CHCl₂CH₂, CCl₂=CH, n=1, 3) in dipolar aprotic solvents — dimethylformamide (DMF), dimethylsulfoxide (DMSO), hexamethylphosphoramide (HMPA) — at 130–150°C react selectively at the CH₂Cl group with salts of carboxylic acids RCO₂K(Na) to form dichloroesters RCO₂· (CH₂)_nR (R=CHCl₂CH₂, CCl₂=CH). In tetrachloroalkanes CCl₃CH₂(CH₂)_nCl (n = 1, 3, 5) under the same conditions the selectivity of the CCl₃ and CH₂Cl groups relative to the nucleophile RCO₂K(Na) is altered — unsaturated esters RCO₂(CH₂)_nCH=CCl₂ are formed in one stage with yields of 75–90%. Under the selected conditions, high conversion of polychloroalkanes to esters is attained 3 to 5 times more rapidly than in acid media. The structure of the ester obtained has been confirmed by their PMR spectra.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2790–2793, December, 1990.     

Transformations of Acylation Products of Functionally 4-Substituted 2-Alkyl(aryl)-5-hydrazino-1,3-oxazoles into 1,3,4-Oxadiazole Derivatives

Acylation products of 2-aryl-5-hydrazino-4-X-1,3-oxazoles [X = C(O)OAlk, P(O)(OAlk)²], when heated in acetic acid or ethanol, undergo recyclization and transform into the derivatives of 1,3,4-oxadiazol-2-ylglycine or its phosphonyl analog. A similar rearrangement also occurs in the reactions of 2-alkyl(aryl)-5-hydrazino-1,3-oxazole-4-carbonitriles with carboxylic acid chlorides in pyridine, but it is accompanied by additional cyclization involving the amide residue and nitrile group, yielding 2-(5-amino-1,3-oxazol-4-yl)-1,3,4-oxadiazole derivatives.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 3, 2005, pp. 461–467.Original Russian Text Copyright © 2005 by Golovchenko, Pil’o, Brovarets, Chernega, Drach.     

Adamantane and its derivatives. 1. Hydrazones and pyrazolones of adamantane

The dihydrazones, bis(diphenylhydrazones), and bis (2,4-dinitrophenylhydrazones) of adamantanone-2-carboxylic acid, dimethyl adamantane-2,6-dione-1,5-dicarboxylate, and tetramethyl adamantane-2,6-dione-1,3,5,7-tetracarboxylate and the pyrazolones of the corresponding acids were synthesized. It is shown that the methyl esters of adamantane-2,6-dione-1,5-dicarboxylic and -1,3,5,7-tetracarboxylic acids and their hydrazones cannot be converted to adamantane-1,5-dicarboxylic and -1,3,5,7-tetracarboxylic acids under the conditions of the Huang-Minlon and Locke reactions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 528–531, April, 1982.     

Mass-spectrometric and quantum-chemical study of fragmentation of diallyl esters of dicarboxylic acids

In a mechanistic study of thermal breakdown of diallyl polymers, six diallyl esters of dicarboxylic acids have been investigated by means of mass spectrometry. A characteristic feature of the fragmentation of these compounds is the low stability of the molecular ions and detachment of the allyl cation, the peak of which is usually the highest in the mass spectrum. In interpreting such an unusual path of fragmentation of esters, quantum-chemical calculations have been carried out in the MINDO/3 approximation; the preferred conformation of the diallyl maleate molecule and the distribution of electron density in this conformation have been determined, and the most stable cyclic structure of the intermediate cation [CH=CH(CO)₂OH]⁺ has been established. The nature of the bridge between the carboxyl groups in diallyl esters of dicarboxylic acids has practically no influence on the direction of fragmentation. The decisive factor in the fragmentation is the electrostatic interaction of charges on the atoms of carbonyl carbon and ester oxygen of the second carboxyl group. A fragmentation scheme with the formation of intermediate cyclic cations is proposed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 3, pp. 300–307, May–June, 1990.     

Carboxyimidazoles in the mannich reaction

Depending on the reagent ratio, 5-dimethylaminomethyl-4-imidazole-4-carboxylic acid and 2,4,5-tris(dimethylaminomethyl)imidazole were obtained in the aminomethylation of imidazole-4-carboxylic and imidazole-4,5-dicarboxylic acids. The oxidation of these compounds with nitric acid leads to imidazole-4,5-dicarboxylic acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 206–208, February, 1989.     

Fluorolactonization of norbornenecarboxylic acids and their methyl esters with F-TEDA-BF4 and XeF2

The selective fluorolactonization was achieved by treatment of cis-5-norbornene-2,3-endo-dicarboxylic acid or its monomethyl and dimethyl esters with F-TEDA-BF₄ or XeF₂. The reactions of 5-norbornene-endo-2-carboxylic acid and its monomethyl ester with F-TEDA-BF₄ or XeF₂ proceed in a non-selective manner to give fluorolactonization, addition and rearrangement products. The basic factor responsible for selectivity of the fluorolactonization is the presence of two endo-oriented carboxyl groups in the substrate molecule. The electrophilicity and type of the fluorinating agent is of secondary importance in this regard. It is postulated that the fluorolactonization of norbornenecarboxylic acids and their methyl esters with F-TEDA-BF₄ or XeF₂ is realized mainly via “open” fluoronorbornyl carbocation intermediates which in the reaction with XeF₂ are postulated as the tight ion pairs.     

Mass-spectrometric investigation of coordination compounds of nickel(II) with radical anions of S-alkyl-1-phenylisothiosemicarbazides

The electron-impact mass spectra of coordination compounds of nickel(II) with the general formula NiL₂, in which the radical anions [C₆H₅N -N-C(SR)=NR¹]^–, where R=CH₃ and R=H(I), R=CD₃ and R=H(II), R=C₂H₅ and R=H(III), and R=CH₃ and R=C₆H₅(IV), serve as the ligands, have been studied. In the mass spectra of compounds I–IV the peaks of the molecular ions have the highest intensity among the organometallic fragments. The initial stage of the fragmentation of [M]^+. is associated with the formation of the rearrangement ions [NiL + H]⁺, [NiL + C₆H₅]⁺, and [NiL + SR]⁺, ions, whose appearance becomes understood, if it is taken into account that the removal of one ligand is accompanied by the impairing of spins and the mass spectra of compounds I–IV is the presence of lines for the [NiL]⁺ ion in them. The dissociative ionization of compounds I–IV is strongly reminiscent of the behavior of ordinary complexes of metals with ligands of the nonradical type. The fragmentation scheme of the molecular ions under the effects of electron impact has been presented and discussed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 3, pp. 368–371, May–June, 1990.     

Silicon-containing esters of α-cyanoacrylic acid: synthesis and properties

A number of cyanoacetates have been synthesized: cyanoacetoxymethyitrimethylsilane (1), cyanoacetoxymethylpentamethyldisiloxane (2), cyanoacetoxyetoxymethylpentamethyldisiloxane (3). They were converted by the Knoevenagel reaction to novel esters of a-cyanoacrylic acid (4–13) containing silicon atoms in the ester groups and having the general formula RCH=C(CN)COOCH₂X (where R=H, 4-MeOC₆H₄, MeCH=CH, 2-furyl; X=SiMe₃, SiMe₂OSiMe₃, CH₂OCH₂SiMe₂OSiMe₃). These compounds are capable of copolymerization with esters of cyanoacrylic acid which are the precursors to adhesives for cold curing.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 949–952, May, 1993.