Studies on furan derivatives IV. A simple preparation of α-substituted β-(5-nitro-2-furyl)ethynyls from α-substituted β-(5-nitro-2-furyl)vinylamines

α-Substituted β-(5-nitro-2-furyl)ethynyls were conveniently prepared by the deamination of α-substituted β-(5-nitro-2-furyl)vinylamines. Also the application of this reaction toward α,β-bis(p-nitrophenyl)vinylamine was examined and afforded α,β-bis(p-nitrophenyl)ethynyl as the main product.     

Synthesis and properties of 5-(5-nitro-2-furyl)thiazolines

The reactions of 2-amino-4-methyl-5-(5-nitro-2-furyl)thiazole with excess methyl iodide leads to 3,4-dimethyl-2-methylamino-5-(5-nitro-2-furyl)thiazolium iodide, which is converted to 2-imino-3,4-dimethyl-5-(5-nitro-2-furyl)thiazoline under the influence of bases. The iminothiazoline structure was proved by comparison of the spectral characteristics of its acetyl derivative and the isomeric 2-(N-acetyl-N-methyl) amino-4-methyl-5-(5-nitro-2-furyl)thiazole. The pKa values of 2-amino-4-methyl-5-(5-nitro-2-furyl)thiazole and 3,4-dimethyl-2-imino-5-(5-nitro-2-furyl)-thiazoline were determined, and the constant of the aminothiazole-iminothiazoline tautomeric equilibrium was calculated.Translated from Khimiya Geterosiklicheskikh Soedinenii, No. 10, pp. 1337–1340, October, 1985.     

Synthesis and properties of 2-amino-5-(5-nitro-2-furyl) thiazole derivatives

The hydrochlorides of the corresponding 2-aminothiazoles, which were converted to the free bases, were obtained by hydrolysis of 2-acylamino-5-(5-nitro-2-furyl) thiazoles. Reactions that take place at the amino group of 2-amino-5-(5-nitro-2-furyl)thiazoles are described.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1038–1041, August, 1985.     

Nitration of 2- and 4-[2-(2-furyl)vinyl]thiazole derivatives

Nitration of 4-methyl-2-[2-(nitro-2-furyl)vinyl]thiazole with a mixture of concentrated nitric and sulfuric acids leads to 4-methyl-5-nitro-2-[2-(3,5-dinitro-2-furyl)vinyl]thiazole. Under the same conditions 2-methyl- and 2-acetamido-4-[1-R-2-(5-nitro-2-furyl)vinyl]thiazoles (R=CH₃, Cl) are nitrated in the 3 position of the furan ring, 2-amino-4-[1-chloro-2-(5-nitro-2-furyl)vinyl]thiazole is nitrated in the 5 position of the thiazole ring and 2-acetamido-5-nitro-4-[2-(2-furyl)vinyl]thiazole undergoes profound changes. Under the influence of a mixture of of nitric acid and acetic anhydride the latter compound is converted quantitatively to the 5-nitro derivative (with respect to the furan ring), whereas 4-[2-(5-nitro-2-furyl)vinyl]thiazole derivatives do not undergo reaction.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 314–317, March, 1977.     

The application of levulinic acid and 5-nitro-2-furylmethylene diacetate in the total synthesis of some novel biologically active (5-nitro-2-furyl)azomethines

Summary The syntheses andin vitro antibacterial and antifungal evaluation of certain (5-nitro-2-furyl)azomethines with different heterocyclic nuclei are described.

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Die Anwendung von Lävulinsäure und 5-Nitro-2-furylmethylendiacetat in der Totalsynthese einiger neuer biologisch aktiver (5-Nitro-2-furyl)azomethine

Zusammenfassung Es wird die Synthese und diein-vitro-antibakterielle und antifungale Wirksamkeit für bestimmte (5-Nitro-2-furyl)azomethine mit verschiedenen heterocyclischen Kernen beschrieben.

     

Nitropyridines: IV. Synthesis of 3-(2-furyl)biphenyls by recyclization of nitropyridinium salts

The two-component Hantzsch synthesis using 3-(2-furyl)-2-nitro-1-phenylprop-2-en-1-one and various enamines gave the corresponding nitro-substituted dihydropyridines which were converted into nitropyridines and N-methylpyridinium salts. Recyclization of the latter by the action of aqueous-alcoholic alkali led to the formation of 3-(2-furyl)-2-nitrobiphenyl derivatives.     

Syntheses of substituted 2-(1-methyl-5-nitro-2-benzimidazolyl)quinolines

Reaction of N-methyl-2-amino-4-nitroaniline ( 1 ) with lactic acid afforded 2-(1-hydroxyethyl)-1-methyl-5-nitrobenzimidazole ( 2 ). Oxidation of compound 2 with chromic acid in acetic acid gave 2-acetyl-1-methyl-5-nitrobenzimidazole ( 3 ). Reaction of compound 3 with substituted 2-aminobenzaldehyde ( 4 ) under basic conditions yielded substituted 2-(1-methyl-5-nitro-2-benzimidazolyl)quinolines ( 5 ). Condensation and cyclization of o-aminoacetophenone (or substituted o-aminobenzophenones) with compound 3 under acetic condition afforded compound 7 . Condensation and cyclization of compound 1 with indole-3-carboxaldehyde ( 11 ) in ethanol in the presence of excess nitrobenzene gave 3-(1-methyl-5-nitro-2-benzimidazolyl)indole ( 12 ).     

Nitrofuranyl heterocycles. XIII N-methyl-3-methylthio-5-(5-nitro-2-furanyl)-1H-1,2,4-triazoles

A continuing search for new nitrofurans which might possess useful antimicrobial activity led to the synthesis of several 3-mercapto-5-(5-nitro-2-furanyl)-1H-1,2,4-triazoles and their methylated derivatives. This paper describes the preparation of these compounds together with proof of structure of the N-methylated products.     

Aminomethylation of 2-(2-furyl)imidazo-[1,2-a]pyridine

The aminomethylation (morpholino- and piperidinomethylation) of 2-(2-furyl)imidazo[1,2-a]-pyridine proceeds primarily at the 3 position of the imidazopyridine system at equimolecular ratios of the reagents, but also proceeds at the 5 position of the furan ring when there is a slight excess of formaldehyde and amine. The structure of the product of monomorpholinomethylation was proved by nitration to give a mononitro derivative that was identical to the 3-morpholinomethyl-2-(5-nitro-2-furyl)imidazo[1,2-a]pyridine prepared by the morpholinomethylation of 2-(5-nitro-2-furyl)imidazo[1,2-a]pyridine. Thin-layer chromatography and IR and UV spectroscopy were used to prove the structures.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 818–821, June, 1971.     

2-(5-Bromo-2-furyl)quinoxaline and 3-(5-bromo-2-furyl)-2-quinoxalone

2-(5-Bromo-2-furyl)quinoxaline and 3-(5-bromo-2-furyl)-2-quinoxalone were obtained by the action of bromine on the corresponding quinoxaline derivatives and also by condensation of o-phenylenediamine with, respectively, (5-bromo-2-furyl)glyoxal or (5-bromo-2-furyl)glyoxylic acid esters.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 404–406, March, 1973.     

Synthesis of 2-phenyl-3-(2-furyl) — and 2-phenyl-3-[β-(2-furyl)vinyl]-1,2-dihydro-naphtho[1,2-d]-1,2,4-triazines

The corresponding 2-phenyl-3-(2-furyl)- and 2-phenyl-3-[-(2-furyl)vinyl]-1,2-dihydronaphtho-[1,2-d]-1,2,4-triazines were obtained by heating Schiff bases [prepared by reaction of 1-(phenyl-azo)-2-aminonaphthalene with furfural, -(2-furyl)acrolein, and their 5-bromo and 5-nitro derivatives] in glacial acetic acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 158–160, February, 1973.     

Synthesis and alkylation of n<Subscript>(3)</Subscript>-aryl-n<Subscript>(5)</Subscript>-phenyl-6-amino-4-aryl(2-furyl)-2-thioxo-1,2,3,4-tetrahydropyridine-3,5-dicarboxamide

N₍₃₎-Aryl-N₍₅₎-phenyl-6-amino-4-aryl(2-furyl)-2-thioxo-1,2,3,4-tetrahydropyridine-3,5-dicarboxamides have been obtained by the interaction of N-phenyl-3-aryl(2-furyl)-2-cyanoacrylamides with 3-amino-3-thioxopropananilides under the conditions of the Michael reaction. N₍₃₎-Aryl-N₍₅₎-phenyl-2-alkylthio-6-amino-4-aryl(2-furyl)-3,4-dihydropyridine-3,5-dicarboxamides and N₍₃₎, N₍₅₎-diphenyl-6-benzylthio-4-(2-furyl)-2-oxo-1,2,3,4-tetrahydropyridine-3,5-dicarboxamides were synthesized by alkylation of the products. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1018–1023, July, 2008.     

1H-NMR,Ultraviolet and infrared spectra of some (Z)-α-(phenyl)-β-(2-furyl), -(2-pyrrolyl) and -(N-methyl-2-pyrrolyl)acrylonitriles

The ¹H-nmr data of some (Z)-α-(p-substituted-phenyl)-β-(2-furyl), -(2-pyrrolyl), and -(N-methyl-2-pyrrolyl)-acrylonitriles have been investigated to indicate the preferred conformation and to establish the conformational preferences of the β-heterocyclic ring. The ultraviolet spectra have been discussed in order to obtain information about the chromophores responsible for the absorption. The infrared spectra have been analyzed for the identification of the main absorption frequencies of cyano and ethylenic groups and to assign the characteristic absorption bands to specific normal vibrations of the heteroaromatic nuclei.     

4-Acetyl-1-(R-benzylidene)-3-(5-nitro-2-furfuryl)thiosemicarbazides — Carriers of synthones for obtaining thiazole and triazole rings

The corresponding thiosemicarbazonium salts, which form 4-acetyl- and 2,4-di-acetyl-1-benzylidene-3-(5-nitro-2-furfuryl)thiosemicarbazides with acetic anhydride, were obtained by the reaction of 5-nitrofurfuryl bromide with 1-benzyl-idenethiosemicarbazides. Under the influence of bases the monoacetylated derivatives undergo cyclization to the corresponding 2-benzylidenehydrazino-5-(5-nitro-2-furyl)thiazoles. Intramolecular cyclization of the monoacetylated products to 3-methyl-5-[(5-nitro-2-furfuryl)thio]-1,2,4-triazole, which is accompanied by the elimination of the corresponding benzaldehyde, occurs in the presence of hydrochloric acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 699–704, May, 1988.     

Synthesis of chiral 2-furyl and 3-nitro-7-oxabicyclo[2.2.1]heptane derivatives from sugars

Asymmetric Diels–Alder reactions between 2-methylfuran and chiral (E)-1,2-dideoxy-1-nitroalkenes derived from d-mannose and d-galactose were carried out at room temperature, under 13 kbar pressure. The processes were completely regioselective, and only the four adducts with penta-O-acetyl-1′-C-(4-methyl-3-nitro-7-oxabicyclo[2.2.1]hept-5-en-2-yl)pentitols structures were formed in each case. These adducts, as well as those arising from cycloadditions of the same nitroalkenes and furan, have been converted into chiral derivatives, such as 2-furyl substituted 1-nitrosugars, 2-glyco-4-methyl-3-nitro-7-oxabicyclo[2.2.1]heptanes, and 5,6-exo-epoxy-2-glyco-3-nitro-7-oxabicyclo[2.2.1]hept-5-enes.     

Furylcyclohexenones. 3. Synthesis and properties of 6-acetyl-3(5)-furylcyclohex-2-enones. Molecular and crystal structure of 6-acetyl-3-(2-furyl)-5-phenylcyclohex-2-enone

6-Acetyl-3(5)-furylcyclohex-2-enones were prepared by condensation of furan-containing chalcones with acetylacetone. Acetylcyclohex-2-enones were subjected to C-methylation. Studies by IR and ¹H NMR spectroscopy demonstrated that the resulting compounds occur predominantly in the enol form both in solutions and in the crystalline state. The molecular structure of 6-acetyl-3-(2-furyl)-5-phenylcyclohex-2-enone was established by X-ray diffraction analysis.     

Chemistry of the phenoxathiins and isosterically related heterocycles. XXIX The crystal and molecular structure of 5-(3′-hydroxypyridyl-2′-thio)-4-nitro-1-methylimidazole

Reaction of the dianion of 3-hydroxypyridine-2(1H)-thione with 5-chloro-4-nitro-1-methylimidazole in N,N-dimethylformamide led to the formation of 5-(3′-hydroxypyridyl-2′-thio)-4-nitro-1-methylimidazole, which failed to cyclize to the desired pyrid[1,4]oxathiinoimidazole derivative. In an effort to determine why the intermediate phenolate sulfide had failed to cyclize, the crystal structure of the isolated product was determined. The structure refined to R = 0.036.     

Synthesis and properties of 1-methyl-2-phenyl-5-(2-furyl)- and 1-methyl-2-phenyl-5-(2-thienyl)imidazoles

2-Phenyl-5-(2-furyl)- and 2-phenyl-5-(2-thienyl)imidazoles were synthesized by condensation of 2-furoylmethyl and 2-thenoylmethyl acetates with benzaldehyde under the conditions of Weidenhagen reaction. The products were converted to N-methyl derivatives in the KOH-acetone system. The electrophilic substitution reactions of the products (acylation, bromination, nitration, sulfonation, hydroxymethylation) were studied.     

Synthesis and Structural Features of 1-Acyl-1-nitro-2-furyl(thienyl)ethenes

A one-stage synthesis of 1-acyl-1-nitro-2-furyl(thienyl)ethenes was developed and structural assessment of the products was performed by means of ¹H, IR, and UV spectroscopy and dipole moment measurements. The acetyl derivatives have Z configuration, and the benzoyl derivatives, E configuration. The UV and IR spectra, as well as the rather high dipole moments ( 5-6 D) point to an essential contribution in the structures of dipolar forms.     

Thermal reactions of 2-(2-oxo-3-nitro-4-quinolinyl)malonates

Depending on the ester substituent, diethyl 2-(3-nitro-2-oxo-4-quinolinyl)malonates 2 give upon thermolysis ethyl 2-(3-nitro-2-oxo-4-quinolinyl)acetates 4, whereas dimethyl 2-(3-nitro-2-oxo-4-quinolinyl)-malonates 3 cyclize to give 1-methoxycarbonylisoxazolo[3,4-c]quinolin-4(5H)-ones 5. The necessary reaction conditions can be obtained easily with the help of differential scanning calorimetry.