- Novel thiosemicarbazones derived from formyl- and acyldiazines: Synthesis, effects on cell proliferation, and synergism with antiviral agents
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The synthesis of a series of novel thiosemicarbazones (TSC's) derived from various alkyl diazinyl (3-pyridazinyl, 4-pyrimidinyl, 2-pyrazinyl) ketones and 3-pyridazinecarbaldehyde and their evaluation against herpes simplex virus (HSV) and human immunodeficiency virus (HIV) as well as the determination of their cytotoxicity are described. In addition, the effects of combination of such TSC's with the well-known antiviral drugs acyclovir (ACV) and 3'-azido-3'-deoxythymidine (AZT) were studied. Under our experimental conditions, i.e. determination of virus-induced cytopathic effect upon infection of HUT78 cells with HSV-1 and upon infection of MT4 cells with HIV-1, no antiviral activity could be detected with any of the TSC's. However, pronounced effects on proliferation of these rapidly growing T4 lymphocyte cell lines were observed. Clear structure-activity relationships with regard to these cytotoxic effects could be established: compared to pyridine, pyrazine, or pyrimidine-derived TSC's most of the 3- pyridazinyl congeners investigated are less cytotoxic: introduction of a methyl group into C-6 of the pyridazine system or prolongation of the acyl moiety in these compounds has essentially no influence; all compounds bearing an N,N-dimethylamino or a cycloamino substituent are much more toxic than those with an NH2 or NHR substituent; the nature of R in the latter type of compounds has only moderate influence. It has been reported that combination of TSC's with the antiviral agent acyclovir (ACV) results in potentiation of this well-known drug. We evaluated the potential of our series of novel TSC's in combination with ACV for inhibition of HSV-1-induced cytopathic effect in HUT78 cells and in combination with 3'-azido-3'-deoxythymidine (AZT) for inhibition of HIV-1-induced cytopathic effect in MT4 cells. Only four compounds out of this series, all characterized by an unsubstituted NH2 group, exhibited moderate synergism with the above mentioned antiviral drugs. Our results do not support the previously expressed opinion that TSC's are selective antiviral agents. In our test systems no evidence for inhibition of virus-induced cytopathic effect was obtained. The TSC derivatives exhibited a broad range of cytotoxic effects, some at concentrations considerably below those reported to have antiviral efficacy. Several of our novel diazine- derived compounds proved advantageous over the previously described pyridine analogues with regard to cytotoxicity. Moderate synergism could be detected for relatively noncytotoxic TSC's with the antiviral drugs ACV (antiherpes) and AZT (anti-HIV).
- Easmon,Heinisch,Holzer,Rosenwirth
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- Comparison of pyrazines formation in methionine/glucose and corresponding Amadori rearrangement product model
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The generation of pyrazines in a binary methionine/glucose (Met/Glc) mixture and corresponding methionine/glucose-derived Amadori rearrangement product (MG-ARP) was studied. Quantitative analyses of pyrazines and methional revealed that MG-ARP generated more methional compared to Met/Glc, whereas lower content and fewer species of pyrazines were observed in the MG-ARP model. Comparing the availability of α-dicarbonyl compounds generated from the Met/Glc model, methylglyoxal (MGO) was a considerably effective α-dicarbonyl compound for the formation of pyrazines during MG-ARP degradation, but glyoxal (GO) produced from MG-ARP did not effectively participate in the corresponding formation of pyrazines due to the asynchrony on the formation of GO and recovered Met. Diacetyl (DA) content was not high enough to form corresponding pyrazines in the MG-ARP model. The insufficient interaction of precursors and rapid drops in pH limited the formation of pyrazines during MG-ARP degradation. Increasing reaction temperature could reduce the negative inhibitory effect by promoting the content of precursors.
- Cui, Heping,Deng, Shibin,Hayat, Khizar,Ho, Chi-Tang,Zhai, Yun,Zhang, Qiang,Zhang, Xiaoming
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- Highly chemoselective deoxygenation of N-heterocyclic: N -oxides under transition metal-free conditions
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Because their site-selective C-H functionalizations are now considered one of the most useful tools for synthesizing various N-heterocyclic compounds, the highly chemoselective deoxygenation of densely functionalized N-heterocyclic N-oxides has received much attention from the synthetic chemistry community. Here, we provide a protocol for the highly chemoselective deoxygenation of various functionalized N-oxides under visible light-mediated photoredox conditions with Na2-eosin Y as an organophotocatalyst. Mechanistic studies imply that the excited state of the organophotocatalyst is reductively quenched by Hantzsch esters. This operationally simple technique tolerates a wide range of functional groups and allows high-yield, multigram-scale deoxygenation. This journal is
- Kim, Se Hyun,An, Ju Hyeon,Lee, Jun Hee
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supporting information
p. 3735 - 3742
(2021/05/04)
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- Iron-catalyzed Minisci acylation of N-heteroarenes with α-keto acids
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An efficient and mild protocol has been developed for the Minisci acylation reactions of nitrogen-containing heteroarenes with α-keto acids. Distinct from the conventional Minisci acylation conditions, the chemistry was performed using non-noble metal Fe(II), instead of expensive Ag(I) salt, as catalyst. A wide range of substrates, including aliphatic or aromatic α-keto acids, as well as various N-heteroarenes, proved to be compatible with the protocol. Scale-up experiment also demonstrates the practicality of the approach.
- Wang, Xiu-Zhi,Zeng, Cheng-Chu
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supporting information
p. 1425 - 1430
(2019/02/01)
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- Method for synthesizing 2-acetyl pyrazine
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The invention relates to the field of chemical organic synthesis, in particular to a method for synthesizing 2-acetyl pyrazine. The method comprises the following steps: (1) preparation of a Grignardreagent: adding metallic magnesium, an anhydrous polar solvent, elemental iodine and methyl chloride into a pressure vessel, and stirring to prepare the Grignard reagent; (2) adding reaction: adding 2-cyanopyrazine, tetrahydrofuran, a catalyst and the Grignard reagent into a reactor, and refluxing and condensing to obtain an intermediate product; (3) hydrolyzing: adding water into the intermediateproduct, adjusting the pH value by using dilute acid, stirring and refluxing, and then adjusting to be neutral; and finally, extracting with toluene; and (4) aftertreatment: desolventizing a tolueneextracting solution, dissolving desolventized solid with ethanol, adding activated carbon, filtering, and cooling to obtain a white solid P1; and recrystallizing with the ethanol to obtain the 2-acetylpyrazine. According to the method, a monovalent copper salt is adopted as a catalyst, the yield of 2-acetylpyrazine is increased to be 69%, meanwhile, the reaction speed is increased, and the synthesis reaction temperature is also reduced.
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Paragraph 0022-0029
(2019/06/27)
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- Synthetic method of natural 2-acetylpyrazine
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The invention discloses a synthetic method of 2-acetylpyrazine. According to the invention, an intermediate is obtained by adopting 2-ethylpyrazine and chlorine as reactive materials for a substitution reaction, and the intermediate is subjected to a hydrolysis reaction to obtain the 2-acetylpyridyl, wherein a catalyst adopted in the substitution reaction is benzoyl peroxide, the reaction temperature is 50 to 95 DEG C, a solvent in the hydrolysis reaction is a saturated aqueous solution of sodium hydrogen carbonate and an organic solvent, and the organic solvent is a liquid organic compound that can be mutually soluble with water; and a structural formula of the intermediate is shown in the specification. The synthetic method provided by the invention has low requirements on reaction conditions, and is simple in steps and good in operability.
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Paragraph 0043; 0044; 0051; 0053; 0055; 0057; 0059
(2018/11/27)
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- Direct oxidation of the Csp3–H bonds of N-heterocyclic compounds to give the corresponding ketones using a reusable heterogeneous MnOx-N@C catalyst
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Novel reusable MnOx-N@C catalyst has been developed for the direct oxidation of N-heterocycles under solvent-free conditions using TBHP as benign oxidant to give the corresponding N-heterocyclic ketones. The catalytic system exhibited a broad substrate scope and excellent regioselectivity, as well as being amenable to gram-scale synthesis. This MnOx-N@C catalyst also showed good reusability and was successfully recycled six times without any significant loss of activity.
- Ren, Lanhui,Wang, Lianyue,Lü, Ying,Li, Guosong,Gao, Shuang
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p. 1216 - 1221
(2016/09/07)
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- 1H-pyrrole-2,4-dicarbonyl-derivatives and their use as flavoring agents
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The present invention primarily relates to 1H-pyrrole-2,4-dicarbonyl-derivatives of Formula (I) wherein R1, R2, R3, Z. Z' and J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) or of a mixture of compounds of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
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- Imidazo[1,2-a]pyridine-ylmethyl-derivatives and their use as flavoring agents
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The present invention primarily relates to imidazo[1,2-a]pyridine-ylmethyl-derivatives of Formula (I) wherein R1, R2, X, W e J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
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- Formation of pyrazines in maillard model systems of lysine-containing dipeptides
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Whereas most studies concerning the Maillard reaction have focused on free amino acids, little information is available on the impact of peptides and proteins on this important reaction in food chemistry. Therefore, the formation of flavor compounds from the model reactions of glucose, methylglyoxal, or glyoxal with eight dipeptides with lysine at the N-terminus was studied in comparison with the corresponding free amino acids by means of stir bar sorptive extraction (SBSE) followed by GC-MS analysis. The reaction mixtures of the dipeptides containing glucose, methylglyoxal, and glyoxal produced 27, 18, and 2 different pyrazines, respectively. Generally, the pyrazines were produced more in the case of dipeptides as compared to free amino acids. For reactions with glucose and methylglyoxal, this difference was mainly caused by the large amounts of 2,5(6)-dimethylpyrazine and trimethylpyrazine produced from the reactions with dipeptides. For reactions with glyoxal, the difference in pyrazine production was rather small and mostly unsubstituted pyrazine was formed. A reaction mechanism for pyrazine formation from dipeptides was proposed and evaluated. This study clearly illustrates the capability of peptides to produce flavor compounds that can differ from those obtained from the corresponding reactions with free amino acids.
- Van Lancker, Fien,Adams,De Kimpe, Norbert
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scheme or table
p. 2470 - 2478
(2010/09/04)
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- Rhodanineacetic acid derivatives as potential drugs: Preparation, hydrophobic properties and antifungal activity of (5-arylalkylidene-4-oxo-2- thioxo-1,3-thiazolidin-3-yl)acetic acids
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Some [(5Z)-(5-arylalkylidene-4-oxo-2-thioxo-1,3-thiazolidin-3-yl)]acetic acids were prepared as potential antifungal compounds. The general synthetic approach to all synthesized compounds is presented. Lipophilicity of all the discussed rhodanine-3-acetic acid derivatives was analyzed using a reversed phase high performance liquid chromatography (RP-HPLC) method. The procedure was performed under isocratic conditions with methanol as an organic modifier in the mobile phase using an end-capped non-polar C18 stationary RP column. The RP-HPLC retention parameter log k (the logarithm of the capacity factor k) is compared with log P values calculated in silico. All compounds were evaluated for antifungal effects against selected fungal species. Most compounds exhibited no interesting activity, and only {(5Z)-[4-oxo-5-(pyridin-2- ylmethylidene)-2-thioxo-1,3-thiazolidin-3-yl]}acetic acid strongly inhibited the growth of Candida tropicalis 156, Candida krusei E 28, Candida glabrata 20/Iand Trichosporon asahii 1188.
- Dolezel, Jan,Hirsova, Petra,Opletalova, Veronika,Dohnal, Jiri,Marcela, Vejsova,Kunes, Jiri,Jampilek, Josef
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experimental part
p. 4197 - 4212
(2010/03/03)
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- Metal ion chelates of lipophilic alkyl diazinyl ketoximes as hydrolytic catalysts
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A series of lipophilic dodecyl hetaryl ketoximes (hetaryl = pyridin-2-yl, pyridazin-3-yl, pyrimidin-2-yl, pyrimidin-4-yl, pyrazin-2-yl as well as their methyl hetaryl homologues was synthesized and hydrolytic activity of their chelates with Co2+, Ni2+, Cu2+ and Zn2+ in a micellar matrix of hexadecyltrimethylammonium bromide or in homogeneous aqueous solutions was investigated using 4-nitrophenyl acetate, 4-nitrophenyl hexanoate and 4-nitrophenyl diphenyl phosphate as model substrates. While Co2+ and Cu2+ chelates are almost inactive, those of Ni2+ and Zn2+ exhibit considerable activity. None of the studied chelates promotes hydrolysis of the used phosphate. The effective species are chelates of the metal : ligand stoichiometry 1 : 3 and 1 : 1 with Ni2+ and Zn2+, respectively, when the ester cleavage proceeds in the micellar matrix. The 1 : 2 stoichiometry was found in aqueous solutions of Ni2+ and Zn2+ chelates of methyl ketoximes.
- Cibulka, Radek,Hampl, Frantisek,Martinu, Tomas,Mazac, Jiri,Totevova, Sonja,Liska, Frantisek
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p. 1159 - 1179
(2007/10/03)
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- 5-alkyl-l-pyrazinecarboxamides, 5-alkyl-2-pyrazinecarbonitriles and 5-alkyl-2-acetylpyrazines as synthetic intermediates for antiinflammatory agents
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2-Pyrazinecarbonitrile, 2-acetylpyrazine, 5-alkyl-2-pyrazinecarboxamides, 5-alkyl-2-pyrazinecarbonitriles and 5-alkyl-2-acetylpyrazines were prepared as intermediates for use in synthesis of potential antiinflammatory agents. The results of the homolytic alkylation of pyrazinecarboxamide were compared with published data. 2-Acetylpyrazine and its 5-(1,1-dimethylethyl) derivative were screened for biological activity, but no interesting effect was found.
- Opletalova, Veronika,Patel, Asmita,Boulton, Michael,Dundrova, Alice,Lacinova, Eva,Prevorova, Marta,Appeltauerov, Martina,Coufalova, Milada
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p. 1093 - 1101
(2007/10/03)
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- Triplet states mediating hydrogen abstraction in 4-acylpyrimidines, 2-acylpyridines, 2-acylpyrazines, and 3-acylpyridazines
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Irradiation of 9 leads to hydrogen abstraction by N(1) and fragmentation to 8 from a triplet with ET ～78 kcal/mol. Irradiation of 2-acylpyridines (10) leads to abstraction by both nitrogen and oxygen (cf. eq 4), with the same Stern-Volmer kqτ for the two processes. Irradiation of 2-acylpyrazines (11) can lead to abstraction by either nitrogen (φ27 0.77 from 11b) or oxygen (φ11a 0.95 from 11f)- 3-Acylpyridazine 12d is unreactive on direct irradiation or triplet sensitization with sensitizer ET ～70 kcal/mol; it furnishes a small amount of 12a on sensitization by acetone. Ketone 18 is recovered unchanged from irradiation under all conditions used with 12d. These observations suggest a correlation between the photochemistry of each of these compounds and the energy of the nπ* triplet of the heteroaromatic ring. The nature of the excited state(s) responsible for hydrogen abstraction by nitrogen and oxygen in these ketones is discussed.
- Prathapan, Sreedharan,Robinson, Kevin E.,Agosta, William C.
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p. 1838 - 1843
(2007/10/02)
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- Homolytic Acylation of Protonated Pyridines and Pyrazines with α-Keto Acids: The Problem of Monoacylation
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The silver-catalyzed decarboxylation of α-keto acids by persulfate leads to acyl radicals, which can effect the selective homolytic acylation of pyridine and pyrazine derivatives.Compared with the previously developed source of acyl radicals by hydrogen abstraction from aldehydes, this procedure is more effective in monoacylation when multiple positions of high nucleophilic reactivity are available in the heterocyclic ring.Although the introduction of an acyl group strongly activates the heterocyclic ring toward further substitution, monoacylation can be achieved by taking advantage of the difference in basicity and lipophilicity between the starting base and the monoacylation products in a two-phase system.
- Fontana, Francesca,Minisci, Francesco,Barbosa, Maria Claudia Nogueira,Vismara, Elena
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p. 2866 - 2869
(2007/10/02)
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- Preparation of Monoacylpyrazines
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Homolytic acylation of pyrazine and alkylpyrazines by aldehydes, as a source of an acyl radical, gives mainly monoacylation products.The reactions proceed in reasonable yields and provide a new route to pyrazine ketones.
- Houminer, Y.,Southwick, E. W.,Williams, D. L.
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p. 497 - 500
(2007/10/02)
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- ACIDIFYING EFFECTS OF AZA GROUPS IN THE NH ACIDITY OF AMINOAZINES AND THE CH ACIDITY OF ACETYLAZINES
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The pK values for a series of aminoazines and acetylazines containing one, two, or three aza groups in the ring were determined in dimethyl sulfoxide.There is a good linear correlation between pK values of the investigated NH and CH acids.The acidifying effects (ΔpK) of the aza groups at positions 2, 3, or 4 in relation to the side chain were determined and had values of 3.1, 2.4, and 4.5 logarithmic units in the aminoazines and 3.5, 2.9 and 4.8 logarithmic units respectively in the acetylazines.Except in the case of two ortho-located aza groups the effects are additive.Compared with dimethyl sulfoxide water has a differentiating effect on the acidity of the aminoazines, and this is explained by the formation of hydrogen bonds between the molecules of the proton-donating solvent and the aza groups of the anions of the aminoazines.
- Terekhova, M. I.,Petrov, E. S.,Mikhaleva, M. A.,Shkurko, O. P.,Mamaev, V. P.,Shatenshtein, A. I.
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