Alkyl Carboxy Pyrazines

Like pyrazinecarboxylic acids, alkylpyrazinecarboxylic acids are decarboxylated on heating to elevated temperatures. For example, 23-dicarboxypyrazine and 2,3-dicarboxy-5,6-dimethylpyrazine are decarboxylated in acetic acid at 180 to pyrazine and 23-dimethylpyrazine, respectively, but on distillation under vacuum they give 2-carboxypyrazine and 5-carboxy-2,3-dimethylpyrazine, respectively (397). 

Decarboxylation of alkylpyrazine carboxylic acids to alkylpyrazines is discussed fully in Section IX.lC(l). 

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C-Alkyl- and C-arylpyrazines are most generally prepared by primary syntheses, which have been discussed in Chapter II they may also be prepared by alkylation (or arylation) of pyrazines at nuclear or side chain carbon atoms, and by decarboxylation of alkyl carboxy pyrazines. 

All tables include relevant C-alkyl derivatives of the type of pyrazine listed. For example, Table A.2 (aminopyrazines) contains aminopyrazines and A -substituted analogues, as well as C-alkyl derivatives and Table A.21 (carboxy halogenopyrazines) lists 2,6-dichloro-3 -cyano-5 -methylpyrazine. 

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