Recent Advances in Pyazine Chemistry

Publisher This chapter discusses the recent advances in pyazine chemistry. Pyrazine, or 1,4–diazine is a highly symmetrical molecule. Synthetic pyrazines exhibit a wide range of physiological activity, in some cases superior to those of pyridine or pyrimidine analogs. Alkylpyrazines are important flavor constituents of roasted food products such as coffee, cocoa, and peanuts; coffee, for instance, contains 2-isopropyl-5-methylpyrazine. Pyrazine and its alkyl derivatives are potentially useful bidentate ligands and form complexes with the following common transition metals. Pyrazines also possess considerable aromatic character. The main features of their reactivity may be predicted by regarding them as pyridines into which nitrogen has been inserted in the para position. Pyrazines also show close similarity in their reactions to the other diazines, pyrimidines, and pyridazines. The pyrazine ring, like the pyridine ring is stable to oxidizing agents. It is more resistant to alkaline permanganate th.an the benzene ring itself; it also survives strong acid and alkaline treatments that destroy the pyrimidine ring. Pyrazines are more resistant to electrophilic substitution reactions at the ring carbon atoms than the corresponding pyridines.