- Studies on pyrazines. Part 32. Synthesis of trisubstituted and tetrasubstituted pyrazines as ant pheromones
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The synthesis of trialkylpyrazines having methyl groups on C-2 and C-5 is described, which is completed by the cross-coupling reaction of 2-chloro-3,6-dimethylpyrazine with dialkylzinc in the presence of [1,3-bis(diphenylphosphino)propane] nickel(II) chloride. Similarly, 2,5-diisobutyl-, -diisopropyl- and -di-sec-butyl-3-methylpyrazines are prepared from the corresponding dialkyl chloropyrazlnes. The dimethyl products are acylated with an α-keto acid under the Minisci radical conditions providing 2-acyl-5-alkyl-3,6-dimethylpyrazines. Several compounds obtained in this study prove to be active as components of pheromones in ants.
- Sato, Nobuhiro,Matsuura, Tomoyuki
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- Maillard-Lipid Interactions in Nonaqueous Systems: Volatiles from the Reaction of Cysteine and Ribose with Phosphatidylcholine
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Equimolar mixtures of cysteine and ribose mixed with an excess of microcrystalline cellulose powder were heated at 185 deg C with or without the addition of phosphatidylcholine.Volatile products were analyzed by headspace concentration and GC-MS.Sulfur-containing heterocyclic compounds dominated the volatiles, with trithiolanes, trithianes, and thiazoles among the most abundant components.Some qualitative and quantitative differences were found between the volatiles from the reactions performed with and without cellulose.The cellulose was not totally inert; volatiles were formed from its thermal degradation and its reaction with cysteine.In general, the addition of phospholipid had only a small effect on the volatile profile, with small amounts of lipid degradation products and lipid-Maillard interaction products formed.However, three methylthio-substituted furans and thiophenes were found in the phospholipid-containing systems which were not detected in the lipid-free reaction mixtures.Keywords: Maillard reaction; aroma; volatiles; cysteine; ribose; phospholipid
- Mottram, Donald S.,Whitfield, Frank B.
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- Preparation method of 2-ethyl-3,6-dimethylpyrazine
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The invention belongs to the technical field of insect pheromones, and particularly relates to a preparation method of 2-ethyl-3,6-dimethylpyrazine. The preparation method of 2-ethyl-3,6-dimethylpyrazine comprises the following steps: mixing 1-(3,6-dimethylpyrazin-2-yl)ethanone with a dipolyethylene glycol solution of hydrazine hydrate, and carrying out a first reduction reaction to obtain an intermediate solution; and mixing the intermediate solution with an alkaline substance, carrying out a second reduction reaction, and conducting purifying to obtain the 2-ethyl-3,6-dimethylpyrazine. According to the method, 1-(3,6-dimethylpyrazin-2-yl)ethanone, hydrazine hydrate and an alkaline substance are used as reactants, dipolyethylene glycol is used as a solvent, and the 2-ethyl-3,6-dimethylpyrazine is synthesized directly through a reduction method. The purity of the 2-ethyl-3,6-dimethylpyrazine prepared by the preparation method provided by the invention is 88 to 97%, and the yield of the2-ethyl-3,6-dimethylpyrazine is 85 to 95%.
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Paragraph 0047; 0049-0051; 0053-0055; 0057-0059; 0061-0062
(2020/09/16)
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- Synthesis method of 2-ethyl-3,6-dimethyl pyrazine
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The invention discloses a synthesis method of 2-ethyl-3,6-dimethyl pyrazine including the following steps: 1), putting 2,5-dimethyl pyrazine and FeSO4.7H2O into a reaction bottle in proportion, stirring, then adding water as a solvent, and next dropwise a
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Paragraph 0045; 0046; 0047; 0048; 0049; 0050
(2016/11/14)
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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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- Influence of Free Amino Acids, Oligopeptides, and Polypeptides on the Formation of Pyrazines in Maillard Model Systems
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Pyrazines are specific Maillard reaction compounds known to contribute to the unique aroma of many products. Most studies concerning the generation of pyrazines in the Maillard reaction have focused on amino acids, while little information is available on the impact of peptides and proteins. The present study investigated the generation of pyrazines in model systems containing whey protein, hydrolyzed whey protein, amino acids, and glucose. The impact of thermal conditions, ratio of reagents, and water activity (aw) on pyrazine formation was measured by headspace solid-phase microextraction with gas chromatography/mass spectrometry (HS-SPME-GC/MS. The presence of oligopeptides from hydrolyzed whey protein contributed significantly to an increased amount of pyrazines, while in contrast free amino acids generated during protein hydrolysis contributed to a lesser extent. The generation of pyrazines was enhanced at low aw (0.33) and high temperatures (>120 °C). This study showed that the role of peptides in the generation of pyrazines in Maillard reaction systems has been dramatically underestimated.
- Scalone, Gustavo Luis Leonardo,Cucu, Tatiana,De Kimpe, Norbert,De Meulenaer, Bruno
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p. 5364 - 5372
(2015/06/25)
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- Alkylations and hydroxymethylations of pyrazines via green minisci-type reactions
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A new general methodology utilizing Minisci-type chemistry has been developed that cleanly and efficiently prepares alkyl- and (hydroxymethyl) pyrazines. The new methods eliminate toxic catalysts and halogenated solvents, providing a greatly improved route to these natural products which are prevalent in many natural systems as bacterial volatiles, plant volatiles, and insect pheromones.
- Bohman, Bjorn,Berntsson, Benjamin,Dixon, Ruby C. M.,Stewart, Craig D.,Barrow, Russell A.
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supporting information
p. 2787 - 2789
(2014/06/23)
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- Impact of the N-terminal amino acid on the formation of pyrazines from peptides in maillard model systems
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Only a minor part of Maillard reaction studies in the literature focused on the reaction between carbohydrates and peptides. Therefore, in continuation of a previous study in which the influence of the peptide C-terminal amino acid was investigated, this study focused on the influence of the peptide N-terminal amino acid on the production of pyrazines in model reactions of glucose, methylglyoxal, or glyoxal. Nine different dipeptides and three tripeptides were selected. It was shown that the structure of the N-terminal amino acid is determinative for the overall pyrazine production. Especially, the production of 2,5(6)-dimethylpyrazine and trimethylpyrazine was low in the case of proline, valine, or leucine at the N-terminus, whereas it was very high for glycine, alanine, or serine. In contrast to the alkyl-substituted pyrazines, unsubstituted pyrazine was always produced more in the case of experiments with free amino acids. It is clear that different mechanisms must be responsible for this observation. This study clearly illustrates the capability of peptides to produce flavor compounds such as pyrazines.
- Van Lancker, Fien,Adams, An,De Kimpe, Norbert
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scheme or table
p. 4697 - 4708
(2012/08/27)
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- Pyrazine biosynthesis in corynebacterium glutamicum
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The volatile compounds released by Corynebacterium glutamicum were collected by use of the CLSA technique (closed-loop stripping apparatus) and analysed by GC-MS. The headspace extracts contained several acyloins and pyrazines that were identified by their synthesis or comparison to commercial standards. Feeding experiments with [2H7]acetoin resulted in the incorporation of labelling into trimethylpyrazine and tetramethylpyrazine. Several deletion mutants targeting genes of the primary metabolism, were constructed to elucidate the biosynthetic pathway to pyrazines in detail. A deletion mutant of the ketol-acid reductoisomerase was not able to convert the acetoin precursor (S)2-acetolactate into the pathway intermediate (R)-2,3-dihydroxy-3-methylbutanoate to the branched amino acids. This mutant requires valine, leucine, and isoleucine for growth and produces significantly higher amounts and more different compounds of the acyloin and pyrazine classes. Gene deletion of the acetolactate synthase (AS) resulted in a mutant that is not able to convert pyruvate into (5)-2-acetolactate. This mutant also requires branched amino acids and produces only very small amounts of pyrazines likely from valine via the valine biosynthetic pathway operating in reverse order. A ΔASΔKR double mutant was constructed that does not produce any pyrazines at all. These results open up a detailed biosynthetic model for the formation of alkylated pyrazines via acyloins.
- Dickschat, Jeroen S.,Wickel, Susanne,Bolten, Christoph J.,Nawrath, Thorben,Schulz, Stefan,Wittmann, Christoph
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supporting information; experimental part
p. 2687 - 2695
(2010/08/07)
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- The effect of pH on the formation of aroma compounds produced by heating a model system containing l-ascorbic acid with l-threonine/l-serine
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The identification of aroma compounds, formed from the reactions of l-ascorbic acid with l-threonine/l-serine at five different pH values (5.00, 6.00, 7.00, 8.00, or 9.55) and 143 ± 2 °C for 2 h, was performed using a SPME-GC-MS technique, and further use
- Yu, Ai-Nong,Zhang, Ai-Dong
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experimental part
p. 214 - 219
(2011/12/14)
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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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- Mechanisms of Formation of Alkylpyrazines in the Maillard Reaction
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The formation of alkylpyrazines was investigated in the reaction of glucose and fructose with -alanine and glycine.The reaction systems were heated for 7 min at 180 deg C.GC-MS and GC-MS/MS data were used to determine the rate of incorporati
- Amrani-Hemaimi, Miriam,Cerny, Christoph,Fay, Laurent B.
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p. 2818 - 2822
(2007/10/03)
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- SYNTHESIS OF NITROGEN CONTAINING HETEROCYCLES OVER COPPER CHROMITE
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The reactions of 1,2-diaminopropane, 1-amino-2-propanol, 1-amino-2-ethanol, and N-(β-aminoethyl)-1,2-diaminoethane in the gas phase over copper chromite have been investigated with the objective of synthesising nitrogen containing heterocycles.At 240-360
- Meksh, P.A.,Anderson, A.A.,Shimanska, M.
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p. 822 - 828
(2007/10/02)
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- Regioselective Synthesis of Alkylpyrazines
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A new, regioselective synthesis of alkylpyrazines begins with condensation of α-oximido carbonyl compounds with allylamines.The resulting imines are isomerized in the presence of potassium tert-butoxide to the corresponding 1-hydroxy-1,4-diazahexatrienes.Thermal electrocyclization-aromatization to pyrazines is best performed after O-acylation of the oximes with methyl chloroformate.
- Buechi, George,Galindo, Jose
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p. 2605 - 2606
(2007/10/02)
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- ETHYLATION OF PYRAZINES USING ALKYLMETALS, SUCH AS TRIETHYLALUMINUM, DIETHYLZINC, AND TRIETHYLBORANE
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Triethylaluminum, diethylzinc and triethylborane were used for the ethylation of pyrazines.Among these reagents, triethylborane gave the best results.
- Ohta, Akihiro,Ohta, Masakatsu,Igarashi, Yoshiaki,Saeki, Kaemi,Yuasa, Kayo,Mori, Tomoko
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p. 2449 - 2454
(2007/10/02)
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