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1-Methylpyrrole

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Axel Marchal – One of the best experts on this subject based on the ideXlab platform.

  • Toward a Molecular Understanding of the Typicality of Chardonnay Wines: Identification of Powerful Aromatic Compounds Reminiscent of Hazelnut.
    Journal of Agricultural and Food Chemistry, 2017
    Co-Authors: Jacques Gros, Valérie Lavigne, Fannie Thibaud, Marine Gammacurta, Virginie Moine, Denis Dubourdieu, Philippe Darriet, Axel Marchal

    Abstract:

    Chardonnay wines impart a unique complex aroma characterized by its buttery, yellow stone fruit, melon, bready, and woody notes. Among the terms used in the sensory analysis of these wines, this study investigated hazelnut-like attributes. Multidimensional gas chromatography coupled to olfactometry identified five pyrroles reminiscent of hazelnut: 1-ethylpyrrole-2-carboxaldehyde, 1H-pyrrole, 2-acetyl-1H-pyrrole (first identification in wine), 1-Methylpyrrole-2-carboxaldehyde, and 1H-pyrrole-2-carboxaldehyde. Quantitative analyses demonstrated their significantly higher abundance in Chardonnay wines. However, they proved irrelevant in sensory terms, given the low amounts measured in wine compared to their olfactory detection threshold. Nevertheless, the presence of methanethiol derivatives from these pyrroles was investigated in wine. 1-Methylpyrrole-2-methanethiol and 1-ethylpyrrole-2-methanethiol were identified and exhibited hazelnut-like aroma. These compounds, which have not been observed in natural p…

  • Toward a molecular inderstanding of the typicality of chardonnay wines: identification of powerful aromatic compounds reminiscent of hazelnut
    Journal of Agricultural and Food Chemistry, 2017
    Co-Authors: Jacques Gros, Valérie Lavigne, Fannie Thibaud, Marine Gammacurta, Virginie Moine, Denis Dubourdieu, Philippe Darriet, Axel Marchal

    Abstract:

    Chardonnay wines impart a unique complex aroma characterized by its buttery, yellow stone fruit, melon, bready, and woody notes. Among the terms used in the sensory analysis of these wines, this study investigated hazelnut-like attributes. Multidimensional gas chromatography coupled to olfactometry identified five pyrroles reminiscent of hazelnut: 1-ethylpyrrole-2-carboxaldehyde, 1H-pyrrole, 2-acetyl-1H-pyrrole (first identification in wine), 1-Methylpyrrole-2-carboxaldehyde, and 1H-pyrrole-2-carboxaldehyde. Quantitative analyses demonstrated their significantly higher abundance in Chardonnay wines. However, they proved irrelevant in sensory terms, given the low amounts measured in wine compared to their olfactory detection threshold. Nevertheless, the presence of methanethiol derivatives from these pyrroles was investigated in wine. 1-Methylpyrrole-2-methanethiol and 1-ethylpyrrole-2-methanethiol were identified and exhibited hazelnut-like aroma. These compounds, which have not been observed in natural products to date, are potent volatile compounds with detection thresholds of 0.7 and 1.4 ng/L, respectively, in model wine. These findings open up promising perspectives concerning the interpretation of the typical aromatic nuances of some Chardonnay wines.

Francisco J Hidalgo – One of the best experts on this subject based on the ideXlab platform.

  • Effect of the pyrrole polymerization mechanism on the antioxidative activity of nonenzymatic browning reactions.
    Journal of Agricultural and Food Chemistry, 2003
    Co-Authors: Francisco J Hidalgo, Fátima Nogales, Rosario Zamora

    Abstract:

    The present investigation was undertaken to study how the antioxidative activity (AA) of nonenzymatic browning reactions is changing at the same time that the browning (by the pyrrole polymerization mechanism) is being produced. The antioxidative activities of eight model pyrroles (pyrrole, 1-Methylpyrrole, 2,5-dimethylpyrrole, 1,2,5-trimethylpyrrole, 2-acetylpyrrole, 2-acetyl-1-Methylpyrrole, pyrrole-2-carboxaldehyde, and 1-methyl-2-pyrrolecarboxaldehyde) as well as the browning reaction of 2-(1-hydroxyethyl)-1-Methylpyrrole (HMP) and the dimer (DIM) produced during HMP browning were determined. The results obtained suggest that the AAs observed in nonenzymatic browning reactions are the result of the AAs of the different oxidized lipid/amino acid reaction products formed. Thus, the different pyrrole derivatives produced in these reactions had different AAs, and the highest AAs were observed for alkyl-substituted pyrroles without free alpha-positions. Because some of these pyrrole derivatives are implicated in nonenzymatic browning production and this browning production implies the loss of hydroxyl groups and the transformation of some pyrroles with one type of substitution into others, changes in AA during browning production were observed, and the resulting DIM derivative was more antioxidant than HMP or higher polymers. These results explain the AA observed in fatty acid/protein mixtures after slight oxidation and suggest that, when the pyrrole polymerization mechanism is predominant, slightly browned samples may be more antioxidant than samples in which nonenzymatic browning has been highly developed.

  • antioxidative activity of pyrrole imidazole dihydropyridine and pyridinium salt derivatives produced in oxidized lipid amino acid browning reactions
    Journal of Agricultural and Food Chemistry, 1996
    Co-Authors: Manuel Alaiz, Rosario Zamora, Francisco J Hidalgo

    Abstract:

    The antioxidative activity of several models of nonenzymatic browning reaction products was evaluated to determine if the lipid peroxidation process in the presence of amino acids is always accompanied by formation of products with antioxidative properties. 1-Methylpyrrole (1), 1,2,5-trimethylpyrrole (2), 2-(1-hydroxyethyl)-1-Methylpyrrole (3), 2-acetyl-1-Methylpyrrole (4), 1-methyl-4-pentyl-1,4-dihydropyridine-3,5-dicarbaldehyde (5), 1-(2-hydroxyethyl)-2-hexyl-3,5-dipentylpyridinium chloride (6), 1-(1-ethyl-2-formylethyl)-4-methylimidazole (7), and 1-(1-ethyl-3-hydroxypropyl)-4-methylimidazole (8) were added at two levels of concentration (100 and 200 ppm) to soybean oil which was oxidized under air in the dark at 60 °C. Oil peroxidation was evaluated by using the thiobarbituric acid-reactive substances assay. Compounds 2−8 significantly decreased TBARS formation on soybean oil (p < 0.05) and showed diverse activity as compared among them and with synthetic antioxidants. The order of effectiveness obtain...

  • Antioxidative Activity of Pyrrole, Imidazole, Dihydropyridine, and Pyridinium Salt Derivatives Produced in Oxidized Lipid/Amino Acid Browning Reactions
    Journal of Agricultural and Food Chemistry, 1996
    Co-Authors: Manuel Alaiz, Rosario Zamora, Francisco J Hidalgo

    Abstract:

    The antioxidative activity of several models of nonenzymatic browning reaction products was evaluated to determine if the lipid peroxidation process in the presence of amino acids is always accompanied by formation of products with antioxidative properties. 1-Methylpyrrole (1), 1,2,5-trimethylpyrrole (2), 2-(1-hydroxyethyl)-1-Methylpyrrole (3), 2-acetyl-1-Methylpyrrole (4), 1-methyl-4-pentyl-1,4-dihydropyridine-3,5-dicarbaldehyde (5), 1-(2-hydroxyethyl)-2-hexyl-3,5-dipentylpyridinium chloride (6), 1-(1-ethyl-2-formylethyl)-4-methylimidazole (7), and 1-(1-ethyl-3-hydroxypropyl)-4-methylimidazole (8) were added at two levels of concentration (100 and 200 ppm) to soybean oil which was oxidized under air in the dark at 60 °C. Oil peroxidation was evaluated by using the thiobarbituric acid-reactive substances assay. Compounds 2−8 significantly decreased TBARS formation on soybean oil (p < 0.05) and showed diverse activity as compared among them and with synthetic antioxidants. The order of effectiveness obtain...

Henri Doucet – One of the best experts on this subject based on the ideXlab platform.

  • Synthesis of N -Heterocyclic carbene-palladium-PEPPSI complexes and their catalytic activity in the direct C-H bond activation
    Journal of Organometallic Chemistry, 2018
    Co-Authors: Nazan Kaloğlu, Henri Doucet, Christian Bruneau, Murat Kaloğlu, Muhammad Nawaz Tahir, Cengiz Arici, Pierre H. Dixneuf, Bekir Çetinkaya, İsmail Özdemir

    Abstract:

    Abstract A series of benzimidazolium salts having their two nitrogen atoms substituted by bulky groups have been synthesized. The benzimidazolium salts were readily converted into the corresponding palladium-NHC-PEPPSI complexes with general formula [PdBr2(NHC) (Py)], (NHC = N-heterocyclic carbene; PEPPSI = pyridine-enhanced precatalyst preparation, stabilisation, and initiation). The structures of all new compounds were characterized by NMR, IR spectroscopy and microanalysis techniques, which support the proposed structures. The molecular structure of complex 2g was determined by single-crystal X-ray diffraction study. Next, the palladium-NHC-PEPPSI complexes were used as catalysts in the direct C5-arylation of 1-Methylpyrrole-2-carboxaldehyde by aryl halides. These complexes exhibited moderate to high catalytic activities and gave C-H activation selectively at the C5-position of 1-Methylpyrrole-2-carboxaldehyde. Both electron-donating and electron-withdrawing substituents were well tolerated with catalytic systems based on these complexes, even non-activated aryl chlorides such as chlorobenzene or 4-chlorotoluene were coupled with pyrrole in moderate yields.

  • A Simple and Efficient Synthesis of (Hetero)Aryl-Substituted Benzothiazolyl or Benzoxazolyl Furan, Thiophene and N-methylpyrrole Derivatives through a Palladium-Catalyzed Regioselective C–H Bond Arylation
    Synthesis, 2014
    Co-Authors: Fatma Abdellaoui, Chiraz Youssef, Hamed Ben Ammar, Jean-françois Soulé, Henri Doucet

    Abstract:

    The synthesis of 2-(hetero)aryl-5-benzothiazol-2-yl or -benzoxazol-2-ylfuran, -thiophene, and –1-Methylpyrrole derivatives was accomplished in two steps. 2-(Benzothiazol-2-yl)- or 2-benzoxazol-2-ylfuran, -thiophene, or –1-Methylpyrrole were synthesized by coupling a heteroaryl aldehyde and either 2-mercaptophenol or 2-aminophenol. Then, they were successfully arylated with a wide range of aryl bromides using a phosphine-free palladium protocol; regioselective arylation at C5 of furan, thiophene, or 1-methyl-1 H -pyrrole was observed in all cases. This reaction tolerates a wide variety of substituents on the aryl bromides as well as heteroaryl bromides.

  • Palladium-Catalysed Direct Polyarylation of Pyrrole Derivatives
    ChemCatChem, 2013
    Co-Authors: Liqin Zhao, Christian Bruneau, Henri Doucet

    Abstract:

    The palladium-catalysed direct polyarylation of 1-Methylpyrrole and 1-phenylpyrrole was studied. As the C2 and C5 positions of pyrroles are more reactive for C-H bond functionalisation than the C3 and C4 positions, the formation of 2,5-diarylpyrroles was found to proceed selectively in the presence of 3 equiv. of a variety of aryl bromides. The sequential C2 arylation followed by C5 arylation to prepare non-symmetrically substituted 2,5-diarylpyrroles was also studied. For the synthesis of such pyrroles, higher yields were obtained for the couplings with electron-deficient aryl bromides. The tetraarylation of 1-Methylpyrrole was also achieved. From 4 equiv. of 3,5-bis(trifluoromethyl) bromobenzene, the 2,3,4,5-tetraarylated pyrrole was obtained in good yield.