Abstract Reaction of 2-aminopyrazine 1 with isothiocyanate, isocyanate or dithioketal reagent furnished pteridines 3, 4 in good yield. Thioxo compound 3a was chlorinated, methylated and subsequently displaced by amines. A simple one-step synthesis of heterocondensed pteridines 8–13 by reaction of 2-aminopyrazine with various imino thioacetals was described 8–13.
![10H-Thiazolo[2,3-b]pteridin-10-one, 7,8-dihydro- Structure](https://image.chemsrc.com/caspic/175/63012-75-9.png)