New syntheses and spectral properties of pteridine-related heterocycles from 2,5-diamino-3,6-dicyanopyrazine

The reaction of 2,5-diamino-3,6-dicyanopyrazine (I) as a new pyrazine raw m aterial with alkyl isocyanate in the presence of sodium hydride gave novel heptahydroimidazo[4,5-g]pteridine-2,6,8-trione (2), but with tertiary butyl isocyanate gave trihydroimidazo[4,5-b]pyrazine-2-ones (3). Similar reactio n of 1 with alkyl thioisocyanate followed by alkyl iodide gave tetrahydropy rimido[4,5-g]pteridines (4). The reaction of 1 with alkylamine gave the ami ne-adduct of the cyano groups which was further reacted with arylaldehyde t o give the pyrimido[4,5-g]pteridine (10). The products prepared are all of interest as potential pesticides and fluorescent chromophores.