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 (1) as a new pyrazine raw material with alkyl isocyanate in the presence of sodium hydride gave novel heptahydroirnidazo[4,5‐g]pteridine‐2,6,8‐trione (2), but with tertiary butyl isocyanate gave trihydroimidazo[4,5‐b]pyrazine‐2‐ones (3). Similar reaction of 1 with alkyl thioisocyanate followed by alkyl iodide gave tetrahydropyrimido[4,5‐g]pteridines (4). The reac tion of 1 with alkylamine gave the amine‐adduct of the cyano groups which was further reacted with arylaldehyde to give the pyrimido[4,5‐g]pteridine (10). The products prepared are all of interest as potential pesticides and fluorescent chromophores.