PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “PYRAZINES”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2001

Dimetalation of pyrazines. a one-pot synthesis of multisubstituted pyrazine C-nucleosides.

As a part of our efforts to pursue direct, convergent, and concise methodologies for the synthesis of pyrazine C-nucleosides, we have successfully established a sequential dilithiation-addition method, which allows one to introduce two different functional groups to a pyrazine ring in a one-pot fashion. 2,6-Dichloropyrazine was dilithiated at -100 degrees C and then allowed to react with an electrophile, such as bromine, iodine, or disulfides, followed by a reaction with a protected ribonolactone to afford C-nucleosides. After reduction and deprotection, tetrasubstituted pyrazine C-nucleosides, including 2,6-dichloro-3-iodo-5-(beta-D-ribofuranosyl)pyrazine and 2-bromo-3,5-dichloro-6-(beta-D-ribofuranosyl)pyrazine, were obtained. A tandem reaction sequence occurred when disulfides were used, resulting in the formation of 5,6-bis-methylthio-2-chloro-3-(beta-D-ribofuranosyl)pyrazine and 6-(beta-D-ribofuranosyl)-2,3,5-tris-phenylthiopyrazine.

Antineoplastic Agents↗
PubMedDate not supplied

Studies on pyrazine derivatives. Part VII. Synthesis and tuberculostatic activity of some pyrazine amidines and amidoximes.

In the reaction of 2-cyano-6-alkylaminopyrazines with sec. amines in the presence of anhyd. AlCl3 amidines 1-13 were obtained. From pyrazine-2-imidoesters, 2-cyano-pyrazines and pyrazine-2-carbothioamides and hydroxylamine, amidoximes 14-49 were easily prepared. These new compounds were, however, of little tuberculostatic activity (MIC between 31.5-2000 mug/cm3).

Amidines↗
PubMed2004

Synthesis, antimalarial activity, and molecular modeling of new pyrrolo[1,2-a]quinoxalines, bispyrrolo[1,2-a]quinoxalines, bispyrido[3,2-e]pyrrolo[1,2-a]pyrazines, and bispyrrolo[1,2-a]thieno[3,2-e]pyrazines.

Three pyrrolo[1,2-a]quinoxalines, 15 bispyrrolo[1,2-a]quinoxalines, bispyrido[3,2-e]pyrrolo[1,2-a]pyrazines, and bispyrrolo[1,2-a]thieno[3,2-e]pyrazines were synthesized from various substituted nitroanilines or nitropyridines and tested for their in vitro activity upon the erythrocytic development of Plasmodium falciparum strains with different chloroquine-resistance status. Bispyrrolo[1,2-a]quinoxalines showed superior antimalarial activity with respect to monopyrrolo[1,2-a]quinoxalines. The best activity was observed with bispyrrolo[1,2-a]quinoxalines linked by a bis(3-aminopropyl)piperazine. Moreover, it was observed that the presence of a methoxy group on the pyrrolo[1,2-a]quinoxaline nucleus increased the pharmacological activity. Drug effects upon beta-hematin formation were assayed and showed similar or higher inhibitory activities than CQ. A possible mechanism of interaction implicating binding of pyrroloquinoxalines to beta-hematin was supported by molecular modeling.

Animals↗
PubMed2002

Novel routes to 1,2,3,4-tetrahydropyrrolo[1,2-a]pyrazines and 5,6,9,10,11,11a-hexahydro-8H-pyrido[1,2-a]pyrrolo[2,1-c]pyrazines.

Condensation reactions of benzotriazole and 2-(pyrrol-1-yl)-1-ethylamine (1) with formaldehyde and glutaric dialdehyde, respectively, afforded intermediates 2 and 6. Subsequent nucleophilic substitutions of the benzotriazole group in 2 and 6 with Grignard reagents, sodium cyanide, and sodium borohydride gave 1,2,3,4-tetrahydropyrrolo[1,2-a]pyrazines 3a-e, 4, 5 and 5,6,9,10,11,11a-hexahydro-8H-pyrido[1,2-a]pyrrolo[2,1-c]pyrazines 7a-c, 8, 9, respectively, in good yields.

Molecular Structure↗
PubMed2001

Hydrothermal syntheses, structures, and properties of [Cu3Cl2CN(pyrazine)] and copper(I) halide pyrazine polymers.

Crystals of copper halide and pseudohalide compounds with pyrazine are synthesized under hydrothermal conditions. The title compound, [Cu3Cl2CNPz] (1) (Pz = pyrazine), is a new copper compound exhibiting an unusual -(Cu3Cl2)- polymeric stair structural motif and three-coordinate cyanide. Compound 1 crystallizes in the monoclinic space group P2(1)/m, with a = 3.6530(7) A, b = 17.160(3) A, c = 6.9800(14) A, beta = 90.58(3) degrees, and Z = 2. In addition, the series of complexes [Cu2X2Pz] for X = Cl (2), Br (3), and I (4) are also crystallized under hydrothermal conditions. The inorganic polymer [Cu2Br2Pz] (3) belongs to the triclinic space group P1, with a = 6.9671(14) A, b = 7.849(2) A, c = 8.099(2) A, alpha = 71.69(3) degrees, beta = 70.71(3) degrees, gamma = 85.43(3) degrees, and Z = 2. The structure of 3, is similar to the recently reported structure for [Cu2Cl2Pz] (2) (Kawata, S.; Kitagawa, S.; Kumagai, H.; Iwabuchi, S.; Katada, M. Inorg. Chim. Acta 1998, 267, 143). The third member of the series, [Cu2I2Pz], is found to be isostructural on the basis of X-ray powder diffraction results. The lattice parameters are refined from indexed reflections to a = 7.115(10) A, b = 8.321(19) A, c = 8.378(17) A, alpha = 71.1(3) degrees, beta = 67.3(1) degrees, and gamma = 83.0(2) degrees. Electronic spectra show that compounds 1-4 have optical band gaps in the range 2.2-2.4 eV. The infrared and Raman spectra as well as the thermal properties of all compounds are presented.

Journal Article↗
PubMed2003

Long-range ferromagnetic ordering in two-dimensional coordination polymers Co[N(CN)2]2(L) [L = pyrazine dioxide (pzdo) and 2-methyl pyrazine dioxide (mpdo)] with dual mu- and mu3-[N(CN)2] bridges.

Two novel coordination polymers of Co(II) with dicyanamide (dca) were obtained by the addition of ancillary ligands of pyrazine dioxide (pzdo) and 2-methyl pyrazine dioxide (mpdo) into the Co-dca binary system, respectively. Co[N(CN)(2)](2)(pzdo) (1) crystallizes in the orthorhombic space group of Pnnm (No. 58) with a = 9.4699(5) A, b = 14.9984(3) A, c = 7.4313(7) A, and Z = 4, while Co[N(CN)(2)](2)(mpdo) (2) is in the monoclinic space group C2 (No. 5) with a = 16.5391(4) A, b = 9.6065(2) A, c = 7.5001(2) A, beta = 105.779(1) degrees, and Z = 4. Both complexes contain similar two-dimensional triangular Co-dca layers, which offer rare examples of mixed 1,5-mu- and mu(3)-dca bridging coordination polymers with long-range ferromagnetic ordering below ca. 2.5 K.

Journal Article↗
PubMed1975

[Hexahydroimidazo[1,5-a]pyrazine. I. Synthesis of 7-methyl-1,5,6,7,8a-hexahydroimidazo[1,5-a]pyrazin-3(2H)-one and derivatives].

The synthesis and pharmacological activity of a series of 2-aryl or alkyl substituted 7-methyl-1,5,6,7,8,8a-hexahydroimidaso[1,5-a]pyrazin-3(2H)-ones, are reported. The 2-aryl derivatives (VI) have been prepared by reaction of 3-(arylaminomethyl)-1-methylpiperazines (IV) have been prepared by reaction of 3-(arylaminomethyl)-1-methylpiperazines (IV) with N,N'-carbonyldiimidazole. Reaction of various anilines with 3-carbomethoxy-1-methylpiperazine (II) and subsequent reduction of the amides (III) afforded the bases (IV). The synthesis of the unsubstituted compound (XII) has been accomplished either by cyclization with sodium methoxide of methyl (1-me-thylpiperazin-3-yl)methylcarbamate (XI) or by reaction of 3-aminomethyl-1-methylpiperazine (XV) with N,N'-carbonyldiimidazole. Reduction of 1-benzyl-2-cyano-4-methylpiperazine (VII) followed by reaction with methyl chloroformate and debenzylation afforded the urethane (XI). The 2-alkyl and 2-alkenyl derivatives (XIII) have been prepared by alkylation of the sodium salt of (XII) in DMF. The compounds of these series have been tested for antiinflammatory, coronary dilator and C.N.S. depressant activities.

Animals↗
PubMed1984

[Hexahydroimidazo[1,5-a]-pyrazine. II. Synthesis of 7-phenyl-1,5,6,7,8,8a-hexahydroimidazo[,5-a]pyrazine-3(2H)-one and derivatives].

The synthesis and activity on the central nervous system of a series of 2-aryl or 2-alkyl-7-phenylhexahydroimidazo[1,5-a] pyrazin-3(2H)-ones (II a-f) are reported. The intermediate 3-carbomethoxy-1-phenylpiperazine (X) was prepared in six steps from aniline and methyl-2-chloroacrylate. Compared with that of derivatives of Zetidoline, the depressant activity of (II a-f) is markedly reduced.

Animals↗
PubMed1982

[Pyrazine-1,4-dioxides fused to heterocycles / 2nd comm.: Synthesis and antibacterial activity of substituted pyrido[2,3-b]pyrazine-1,4-dioxides (author's transl)].

The position selective synthesis of substituted pyrido[2,3-b]-pyrazine-1,4-dioxides is reported. Compound 3g was subjected to a series of screening-tests for antibacterial activity and compared to therapeutical standards. The range of antibacterial activity mainly comprises enterobacteriaceae, above all E. coli, Klebsiella, Proteus and Shigella strains. Activity against gram-positive organisms and Serratia is much weaker and completely lacking with Pseudomonas. Therapeutic activity in septicaemic infections of the mouse is very good, especially in the case of E. coli infection with an ED50 of 13 mg/kg mouse for s.c. application. With p.o. application 3g shows activity comparable to nalidixic acid and nitrofurantoin in the experimental acute pyelonephritis in the mouse. The activity of 3g, however, is clearly inferior to that of gentamicin.

Animals↗
PubMed1976

Studies on pyrazine derivatives. Part V. Synthesis and tuberculostatic activity of some 6-(beta-aminoethoxy)-pyrazine-2-carboxylic acids.

In the reaction of 2-cyano-6-chloropyrazine with sodium beta-aminoethanolates a mixture of nitriles 1 and imidoesters 2 is formed in relation depending on the reaction conditions. Compounds 1 and 2 with H2S and triethylamine give thioamides 3, which were converted into amides 4 and amidoximes 5. Alkaline hydrolysis of the derivatives of 6-(beta-aminoethoxy)-pyrazine-2-carboxylic acid of type 1,2,3 and 5 gave 6-ethoxypyrazine-2-carboxylic acid. The highest antituberculous activity (62-5-125 mug/cm3) showed thioamides 3a and 3b.

Antitubercular Agents↗
PubMedDate not supplied

Studies on pyrazine derivatives--XXXIV. Synthesis and tuberculostatic activity of alpha-oxo ketene dithioacetals pyrazine derivatives.

The alpha-oxo ketene dithioacetalic derivatives (2a-e) were obtained by the reaction of 2-acetylpyrazine (1) with CS2 and appropriate mono- or dihalogeno-compound. An action of the primary amines and diamines upon 3,3-di(methylsulphanyl)-1-(2-pyrazinyl)-2-propen-1-one (2a) yielded 3-(alkylamino)-3-(methylsulphanyl)-1-(2-pyrazinyl)-2-propen-1-on e (3a-g), 1-(2-pyrazinyl)-2-tetrahydro-1H-2-imidazolyliden-1-ethanone (3h) and the 2-hexahydro-2-pyrimidinyliden-1-(2-pyrazinyl)-1-ethanone derivatives (3i-j), respectively. Tuberculostatic activity of the studied compounds was found to be low except the compound 2b (MIC 192-62 micrograms/cm3; MIC 210-31 micrograms/cm3).

Antitubercular Agents↗