Gastaldi pyrazine synthesis

What is Gastaldi pyrazine synthesis?

The Gastaldi pyrazine synthesis is a chemical process used to create pyrazine. This involves the reaction of α-oximinoketones to form α-aminoketones, which then leads to the formation of pyrazine.

Gastaldi pyrazine synthesis - general reaction scheme
Gastaldi pyrazine synthesis
Gastaldi pyrazine synthesis - general reaction scheme
Gastaldi pyrazine synthesis

For example, to obtain 2,5-dicyano-3,6-disubstituted pyrazines, an oximino ketone bisulfite is treated with potassium cyanide, then the resulting product is heated with hydrochloric acid and oxidized. The dicyano compound can also be treated with alkali to yield a 3,6-disubstituted 2-hydroxypyrazine-5-carboxylic acid, which can be decarboxylated to produce a 3,6-disubstituted-2-hydroxypyrazine.

Gastaldi pyrazine synthesis - general reaction scheme
Gastaldi pyrazine synthesis

References

G. Gastaldi, Gazz. Chim. Ital. 51, 233 (1921)

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