Gutknecht Condensation

The synthesis of pyrazine involving the treatment of a ketone with nitrous acid to form an oximino ketone followed by reduction to an α‐amino ketone that dimerizes to dihydropyrazine via a pinacol‐like process and the formed dihydropyrazine is then converted into the pyrazine from the dehydrogenation (or oxidation). This reaction is generally referred to as the Gutknecht condensation. Various examples of this reaction have been represented. This reaction has a wide application in the preparation of pyrazine derivatives.