Reaction of 5‐(3,4‐dimethoxyphenyl)pyrazine‐2,3‐dicarbonitrile with alkyl radicals

The reaction of 5‐(3,4‐dimethoxyphenyl)pyrazine‐2,3‐dicarbonitrile (Ib) with alkyl radicals gives addition products at the C(6)‐position of the pyrazine ring as the intermediates which collapse into substitution products, 6‐alkyl‐5‐(3,4‐dimethoxyphenylpyrazine‐2,3‐dicarbonitrile (II), under oxidative conditions. Under non‐oxidative conditions the intermediate is converted into dihydropyrazine derivatives, 6‐alkyl‐(3,4‐dimethoxy‐phenyl)‐5,6‐dihydropyrazine‐2,3‐dicarbonitrile (III), and 3,6‐disubstituted pyrazine derivatives, 3,6‐dialkyl‐5‐(3,4‐dimethoxyphenyl)pyrazine‐2‐carbonitrile (IV) and 3‐acyl‐6‐alkyl‐5‐(3,4‐dimethoxyphenyl)pyrazine‐2‐carbonitrile (V).