Studies on pyrazines. Part 34.1 Synthetic approach, stability and tautomerism of 2,6-dihydroxypyrazines

Sato, Nobuhiro; Matsumoto, Kaori; Takishima, Masayuki; Mochizuki, Katsura

doi:10.1039/a704415a

Cited by 10 publications

(3 citation statements)

References 6 publications

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“…The preparation of 3,5-substituted-2-hydroxypyrazines 3 is usually undertaken [6,13,[18][19][20][21][22][23][25][26][27][28]31] as follows. The α-ketoaldehyde 1 and the hydrochloride salt of the α-aminoamide 2 are dispersed in methanol, the suspension is cooled (usually at −30 °C) and a concentrated solution of sodium hydroxide is added.…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, a fascinating aspect of this reaction is seen when starting from α-ketoaldehydes (1, R 1 = H, R 2 ≠ H). Indeed, if only an average reaction yield is usually obtained, it is the least expected 3,5-substituted-2-hydroxypyrazine isomer (3, R 1 = H, R 2 ≠ H) which is isolated sometimes along with a much smaller amount of the alternative 3,6-substituted-2-hydroxypyrazines (4, R 1 = H, R 2 ≠ H) [6,13,[18][19][20][21][22][23][24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

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On Reuben G. Jones synthesis of 2-hydroxypyrazines

Legrand¹,

Janin²

2022

Beilstein J. Org. Chem.

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In 1949, Reuben G. Jones disclosed an original synthesis of 2-hydroxypyrazines involving a double condensation between 1,2-dicarbonyls and α-aminoamides upon treatment with sodium hydroxide at low temperature. This discovery turned out to be of importance as even today there are no simple alternatives to this preparation. Across the years, it was employed to prepare 2-hydroxypyrazines but some of its limits, notably regioselectivity issues when starting from α-ketoaldehydes, certainly hampered a full-fledged generation of pyrazine-containing new chemical entities of potential interest in medicinal chemistry. The present text describes some insights and improvements, such as the unprecedented use of tetraalkylammonium hydroxide, in the reaction parameters affecting the regioselectivity and yield when starting from phenylglyoxal and two α-aminoamides. We also suggest a mechanism explaining the counterintuitive occurrence of 3,5-substituted-2-hydroxypyrazine as the major reaction product.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On Reuben G. Jones synthesis of 2-hydroxypyrazines

Legrand¹,

Janin²

2022

Beilstein J. Org. Chem.

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“…Cyclization reactions of furazan and tetrazole: Based upon the reasearch of the transformation of hydrazines into azides using dinitrogen tetroxide and clay supported ferric nitrate 9,10 , we undertook a nitrosation reaction for compound 4 with two kinds of nitrosating reagents i.e., nitrosonium tetrafluoroborate and sodium nitrite in acetic acid. Both of nitrosating regents gave compound 5 as white crystals in about 20 % yield.…”

Section: Scheme-iiimentioning

confidence: 99%

Synthesis of 7-Azidofurazano[3,4-b]tetrazolopyrazine and Isomer's Structure in Different Polarity Solvents

Guo¹,

Liu²,

Jiang³

et al. 2013

Asian J. Chem.

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AJC-13117 7-Azidofurazano[3,4-b]tetrazolopyrazine (FSZPA) was synthesized via methoxylation, nitration hydrazinolysis and azidation, using 2,6dichloropyrazine as a starting material. The structures of 7-azidofurazano [3,4-b]tetrazolopyrazine and intermediates were identified by FTIR, NMR and elemental analysis. 15 N and 13 C NMR spectra showed three isomer forms resulting from the reversible opening and closing between asido and tetrazole depending on polarity of the solvents.

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