- Method for site-selective alkylation of Diazine-N-oxide using phosphonium ylides
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- N - Oxide (Diazine -)N-The position selective Oxides-C alkylation of H) relates to a method alkylation. To the present invention, a plurality of diazine compounds can be alkylated by selectively introducing an alkyl group to a diazine compound known as a core unit structure in a medicine, and synthesis of a plurality of diazine compounds (varenicline) paenibacillin A, which is a natural product, can be synthesized.
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Paragraph 0146; 0147; 0233; 0237; 0239
(2021/04/06)
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- Site-Selective C-H Alkylation of Diazine N-Oxides Enabled by Phosphonium Ylides
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The synthesis of alkylated diazine derivatives is important for their practical utilization as pharmaceuticals and for other purposes. Herein, we describe the metal-free site-selective C-H alkylation of diazine N-oxides using phosphonium ylides that affords a variety of alkylated diazine derivatives with broad functional group tolerance. The utility of this method is showcased by the late-stage functionalization of a commercially available drug such as varenicline. Notably, the sequential C-H alkylation of pyrazine N-oxides for the total synthesis of a pyrazine-containing natural product, paenibacillin A, highlights the importance of this method.
- Ghosh, Prithwish,Kwon, Na Yeon,Han, Sangil,Kim, Saegun,Han, Sang Hoon,Mishra, Neeraj Kumar,Jung, Young Hoon,Chung, Sang J.,Kim, In Su
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supporting information
p. 6488 - 6493
(2019/08/20)
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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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- Regioselective synthesis of trialkylpyrazines via nickel-catalyzed Negishi cross-coupling of pyrazine triflate
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A regioselective synthesis of trialkylpyrazines via nickel-catalyzed cross-coupling reaction of pyrazine triflate is reported. The 5-substituted 2,3-dimethylpyrazine derivatives including trail pheromone components of the ant Eutetramorium mocquerysi have been successfully synthesized in good yields by nickel-catalyzed Negishi cross-coupling reactions of pyrazine triflate mediated by alkyl and arylzinc halides. Georg Thieme Verlag Stuttgart · New York.
- Pitchaiah, Arigala,Hwang, Intaek,Hwang, Jin-Soo,Kim, Hyungrok,Lee, Kee-In
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p. 1631 - 1636
(2012/06/30)
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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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- 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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