Amino esters of heterocyclic dicarboxylic acids

The corresponding amino esters and their complexes with 7,7,8,8-tetracyanoquinodimethane were obtained by the condensation of the acid dichlorides of furan-2,5-dicarboxylic acid and tetrahydrothiophene-2,5-dicarboxylic acid with 8-hydroxy- and 5,7-dibromo-8-hydroxyquinolines. Almost all of the compounds obtained have antimicrobial activity.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 538–540, April, 1972.     

An improved synthesis and some reactions of diethyl 4-oxo-4H-pyran-2,5-dicarboxylate

The reaction of ethyl 2-(dimethylamino)methylene-3-oxobutanoate with diethyl oxalate in the presence of sodium hydride in THF gave diethyl 4-oxo-4H-pyran-2,5-dicarboxylate, from which 4-oxo-4H-pyran-2,5-dicarboxylic and 4-oxo-1-phenyl-1,4-dihydropyridine-2,5-dicarboxylic acids and their derivatives were obtained in good yields.     

2,5-Diamidofuran anion receptors

3,4-Diphenylfuran-2,5-dicarboxylic acid bis-N-phenylamide 1 and 3,4-biphenyl-furan-2,5-dicarboxylic acid bis-N-butylamide 2 have been synthesised and shown to act as fluoride selective anion receptors in DMSO-d₆/0.5% water solution.     

Synthesis and properties of polyurethanes and polyureas containing 2,5-thiophenylene linkage

A novel diisocyanate monomer, thiophene-2,5-diisocyanate (ThDI) was prepared from readily available adipic acid via the intermediate formation of thiophene-2,5-dicarboxylic acid chloride (ThDAC) and thiophene-2,5-dicarboxylic acid azide (ThDAA) which was subjected to a Curtius rearrangement. Polyurethanes and polyureas containing 2,5-thiophenylene linkage were synthesized by the polycondensation of thiophene-2,5-diisocyanate with various diols and diamines, respectively, in N,N-dimethylformamide. Polymerization conditions were optimized and the high yields of polymers were obtained. The identity of ThDI, model compounds, and the resulting polymers was confirmed by elemental analysis and spectroscopic methods. These polyurethanes and polyureas were found to have inherent viscosities in the range of 0.33–0.68 dL/g. Some physical properties of these polymers were also investigated.     

Synthesis of unsaturated esters of pyridine- and quinolinedicarboxylic acids

The divinyl, diallyl, and dipropargyl esters of pyridine-2,4-, pyridine-2,6-, and quinoline-2,4-dicarboxylic acids and the divinyl and dipropargyl esters of pyridine-2,5-dicarboxylic acid have been synthesized.     

Synthesis of selenophene-2,5-dicarboxylic acid

Selenophene-2,5-dicarboxylic acid was obtained by liquid-phase oxidation of 2,5-dimethylselenophene with molecular oxygen.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, p. 1605, December, 1972.     

Solution and solid-state studies of 3,4-dichloro-2,5-diamidopyrroles: formation of an unusual anionic narcissistic dimer

3,4-Dichoro-1H-pyrrole-2,5-dicarboxylic acid bis-phenylamide 3 and 3,4-dichoro-1H-pyrrole-2,5-dicarboxylic acid bis-butylamide 4 have been prepared and shown to deprotonate in the presence of basic anions: the X-ray crystal structure of the tetrabutylammonium salt of 3-H+ reveals the formation of a dimer in the solid state.     

Synthesis of novel 2,5-bis(5-aryl-1,3,4-oxadiazol-2-yl)furans from furan-2,5-dicarboxylic acid dihydrazide and trichloromethylarenes

2,5-Bis(5-aryl-1,3,4-oxadiazol-2-yl)furans are synthesized via the reaction of trichloromethylarenes with furan-2,5-dicarboxylic acid dihydrazide. The structures of the products are confirmed by IR and mass spectra.N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, Moscow 117913, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 993–996, July, 1999.     

Synthesis and configuration of diastereomeric 2,4-, 2,5-, and 2,6-piperidinedicarboxylic acids and their dimethyl esters

The reduction in an acidic medium over a platinum catalysts of 2,4-, 2,5-, and 2.6-pyridinedicarboxylic acids gave cis-2,4-, -2,5-, and -2,6-piperidinedicarboxylic acids, heating of which in an alkaline medium led to thermodynamically equilibrium mixtures of diastereomers. Individual trans-2,5-piperidinecarboxylic acid was isolated. The configurations of the 2,4-, 2,5-, and 2,6-piperidinedicarboxylic acids and their methyl esters were established by means of the PMR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 367–371, March, 1985.     

The thermodynamic properties and thermolysis characteristics of 2,5-dimethyl-2,5-di-(m-carboranoylperoxy)-3-hexine and 1,1-dimethyl-2-propine-1-yl diperoxy ester of m-carborane-1,7-dicarboxylic acid

The standard enthalpies of combustion Δ_c H°_298.15 and formation Δ_f H°_298.15 of 2,5-dimethyl-2,5-di-(m-carboranoylperoxy)-3-hexine and 1,1-dimethyl-2-propine-1-yl diperoxy ester of m-carborane-1,7-dicarboxylic acid and the effective activation energy E _eff of their thermolysis were determined for the first time.     

Synthesis,characterization and crystal structure of a novel three-dimensional supramolecular architecture formed by manganese(II) and pyridine-2,5-dicarboxylic acid

A novel three-dimensional supramolecular compound formed by Mn(II) and pyridine-2,5-dicarboxylic acid of formula [Mn(Pydc)₂(H₂O)₂] (Pydc?=?pyridine-2,5-dicarboxylic acid) has been synthesized and characterized by elemental analyses, IR, electronic spectra, thermogravimetric analysis and X-ray diffraction techniques. The X-ray structure shows that the central Mn(II) ion is coordinated by two water molecules and two chelated Pydc ligands. Water molecules coordinate with Mn(II) ions in the cis mode. Intermolecular hydrogen bonds play an important role in stabilization of the lattice and construction of the supramolecular network.     

Oxidation of 2,5-dimethylpyrazine with oxygen in the vapor phase on oxide catalysts and in the liquid phase in the presence of bases

The vapor-phase oxidation of 2,5-dimethylpyrazine with oxygen on vanadium-molybdenum oxide catalysts modified with silver oxide gives 5-methyl-2-formylpyrazine and 2,5-diformylpyrazine in 37% and 35% yields, respectively. Pyrazine-2,5-dicarboxylic acid was obtained in 53% yield by the liquid-phase oxidation of 2,5-dimethylpyrazine with oxygen in the presence of a strong base and an interphase catalyst.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 532–537, April, 1990.     

Synthesis of 2,5-Dimethylpyrazine-3,6-Dicarboxylic Acid Derivatives

The general synthetic method of pyrazines¹ has been established. The method for synthesizing symmetrically substituted pyrazine derivatives, however, has not been well-studied.² Especially for synthesis of the title pyrazines, it is only described in a few words by Adkins³ and co-workers that ethyl 2-aminoacetoacetate employed in process to preparing of the threonine synthesis is spontaneously autoxidized to give 2,5-dimethyl-3,6-dicarbetoxy pyrazine as a byproduct. On the basis of this finding of Adkins, we have established a convenient method for the synthesis of 2,5-di-methylpyrazine-3,6-dicarboxylic acid derivatives (D_1–5) using the corresponding acetoacetic acid derivatives (A_1–4) as the starting materials (Scheme).     

Synthesis of 3,4-di(methylene)tetrahydrothiophene-1,1-dioxide and its use in organic synthesis

A convenient reaction scheme has been developed for obtaining 3,4-di(methylene)tetrahydrothiophene-1,2-dioxide from the readily available 3,4-dimethyl-2,4-dihydrothiophene-1,1-dioxide through 3,4-di(bromomethyl)-2,5-dihydrothiophene-1,1-dioxide. A feasibility study has been made of the use of the butadiene fragment of the heterocycle in a Dieb—Alder reaction with maleic acid derivatives, and the corresponding adducts have been obtained.DeceasedTranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 173–175, February, 1992.     

Nojirimycin Based 2,5-Diketopiperazines

2,5-Diketopiperazines were prepared and characterized where one of the amino acids is (2S,3R,4R,5S)-3,4,5-trihydroxypipecolic acid. The protected pipecolic acid was synthesized from a selectively protected deoxynojirimycin derivative. The ring closure to give the diketopiperazines, from the dipeptides, was performed by nucleophilic attack of the amino function of the pipecolic acid moiety onto the carbonyl group of the methyl esters.     

Synthesis of two naturally occurring 3-methyl-2,5-dihydro-1-benzoxepin carboxylic acids

[structures: see text] Two naturally occurring 3-methyl-2,5-dihydro-1-benzoxepin carboxylic acids, 6-hydroxy-3-methyl-8-(phenylethyl)-2,5-dihydro-1-benzoxepin-9-carboxylic acid (radulanin E) (1) and 9-hydroxy-3-methyl-2,5-dihydro-1-benzoxepin-7-carboxylic acid (2), were synthesized using Stille coupling followed by Mitsunobu cyclization.     

Photochromism of fulgides and stereoelectronic factors: Synthesis of (E)-4(3)-adamantyhdene-(5)-dicyanomethylene-3(4)-[1-(2,5-dimethylfuryl)ethylidene]tetrahydrofuran-2-one 4 and 4a and (E)-4-adamantylidene-3-[2,6-dimethyl-3,5-bis(p-diethyl-aminostyryl)benzylidene]tetrahydrofuran-2,5-dione 10

In the search for fulgides with potential semiconductor laser compatibility, 4-adamantylidene-5-dicyanomemylene-3-[1-(2,5-dimethyl-3-furyl)ethylidene]tetrahydrofuran-2-one ( 4 ), along with its regioisomer 4a , have been synthesized from the corresponding fulgide 6 containing a succinic anhydride ring by reaction with malononitrile in the presence of diethylamine. Upon irradiation with a uv light at λ_max 350 run, a mixture of 4 and 4a revealed a considerably enhanced bathochromic shift to the visible region, λ_max 605 nm as compared with the starting fulgide 6 which, upon analogous uv irradiation, absorbed at λ_max 515 nm. In the search for semiconductor-laser-compatible fulgides with increased efficiency for the reverse bleaching reaction, another fulgide (E)–adamantylidene-3-[2,6-dimethyl-3,5-bis(p-diethylaminostyryl)-benzylidene]tetrahydrofuran-2,5-dione ( 10 ) was synthesized in seven steps starting from 2-bromo-m-xylene. However, 10 failed to undergo electrocyclic ring-closure upon irradiation with a uv light at λ_max 350 nm. The analogous fulgide 8 , which contains an isopropylidene functionality in place of the adamantyl group of 10 , was resynthesized for comparison, and showed two absorption maxima, one at 545 nm and the other at 620 nm. The missing physico-chemical data for 8 have also been provided.     

Thermal and spectroscopic properties of light lanthanides (III) and sodium complexes of 2,5-pyridinedicarboxylic acid

Pyridine-2,5-dicarboxylic acid, known as isocinchomeric acid is one of six isomers containing two carboxylic groups. Light lanthanide (III) complexes with pyridine-2,5-dicarboxylic acid with general formula Ln₂L₃·nH₂O, where n = 8, 9, were obtained. Their thermal and spectroscopic properties were studied. Sodium salt was obtained as Na₂L·H₂O. Hydrated complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III) and Gd(III) are stable to 313–333 K, whereas Na₂L·H₂O is stable to about 333 K. Dehydration process for all compounds runs in one stage, next they decompose into appropriate lanthanide oxalates, oxocarbonates carbonates and finally to metal oxides. Bands of νCOOH vibrations at 1736 and 1728 cm⁻¹ disappear on complex spectra and ν_as and ν_s of COO⁻ groups appear thus indicating that complexation process took place.     

(2S,5S)-Pyrrolidine-2,5-dicarboxylic acid,an efficient chiral organocatalyst for direct aldol reactions

Enantioselective aldol reaction of ketones with aldehydes catalyzed by (2S,5S)-pyrrolidine-2,5-dicarboxylic acid in the presence of an equal molar amount of Et₃N was described. By using the new chiral organocatalyst, the direct aldol condensation products were obtained in reasonable yields and up to 90% ee.     

Synthesis of 7-azabicyclo[2.2.1]heptane-1,4-dicarboxylic acid, a rigid non-chiral analogue of 2-aminoadipic acid

A non-chiral, rigid 7-azabicyclo[2.2.1]heptane-1,4-dicarboxylic acid, an analogue of 2-aminoadipic acid, has been synthesized in six steps from dimethyl-meso-2,5-dibromohexanedioate in 28% total yield. A key step in the synthesis is double alkylation of a dimethyl pyrrolidine-2,5-dicarboxylate by 1-bromo-2-chloroethane.