Heterocyclic imines and amines. Part XVI. 2,6-Diaminopyrazine and its 1-oxide from iminodiacetonitrile
With palladium–charcoal, 2,6-bishydroxyiminopiperazine (made from iminodiacetonitrile and hydroxylamine at 70°) underwent hydrogen transfer to yield 2,6-diaminopyrazine, characterised as the diacetyl derivative. From iminodiacetonitrile and hydroxylamine in the cold, the bis(amide oxime) resulted but in the hot with added hydroxylamine hydrochloride—conditions which effected a cycloaddition even to nitrilotriacetonitrile—a hydrated complex of 2,6-bishydroxyiminopiperazine and hydroxylamine hydrochloride was formed, together with 2-amino-6-hydroxyaminopyrazine 1-oxide. Reduction of the latter afforded 2,6-diaminopyrazine 1-oxide, which was acetylated to 2,6-diacetamidopyrazine 1-oxide; the latter was deoxygenated to 2,6-diacetamidopyrazine. Attempts to prepare the mono(amide oxime) of iminodiacetonitrile led to a self-condensation product of aminoacetamide oxime, namely 2,5-bishydroxyiminopiperazine. In comparative experiments, o-cyanobenzyl cyanide gave with hydroxylamine 1-amino-3-hydroxyaminoisoquinoline, and with a mixture of hydroxylamine and its hydrochloride in the hot, 1,2,3,4-tetrahydro-1,3-bishydroxyiminoisoquinoline. Aspects of the mass spectra of the various compounds are reported.