Abstract Reaction of 6-ethylamino-3-methyluracil (1) with nitrobenzenes in hexamethylphosphoric triamide gave isoalloxazines in 3.8–18 percent yield. In the presence of potassium carbonate, reaction of 1 with o-fluoronitrobenzene afforded 5-substituted uracil 3 in moderate yield.
![10-ethyl-3-methylbenzo[g]pteridine-2,4-dione Structure](https://image.chemsrc.com/caspic/005/58668-94-3.png)
