A variety of pyrimidine precursors 12–25 were converted into a series of new 7-hydroxylumazines (=7-hydroxypteridine-2,4(1H,3H)-diones) 26–35 which functioned as starting materials for the transformation into the corresponding 7-chlorolumazines 36–45. Subsequent reaction with hydrazine led to the 7-hydrazinolumazines 46–55 which gave on nitrosation the 7-azidolumazines 1 and 56–64. These compounds