The reaction of 2-aminopyrazine 1 with the glyoxal derivatives 2a-c gave the bicyclic imidazolopyrazinones 3a,b and the monocyclic N-substituted aminopyrazines 4b and 5c. Compounds 3 feature unique crystallographic characteristics. Their reactivity towards superoxide anion is about five times the reactivity of Trolox(R), while the monocyclic pyrazines are inactive.
Devillers, I., Declercq, J.-P., De Wergifosse, B., Bruneau, M.-P., Tinant, B., Touillaux, R., Rees, J.-F., & Marchand-Brynaert, J. (1999). Synthesis, structural characterization and antioxidative properties of aminopyrazine and imidazolopyrazine derivatives. Royal Society of Chemistry. Journal: Perkin Transactions 2, 7, 1481-1487. https://doi.org/10.1039/a900289h (Original work published 1999)