Abstract
Pyrido[2,3-d]pyrimidine derivatives are of chemotherapeutic interest since they have been shown1 to act as inhibitors of dihydrofolate reductase and also because of their reported2 anti-tumor activity. In view of the important biological implications of this ring system, we have investigated a new route to these substances. This paper details a simple and efficient route to the previously unknown 7-amino-1,3-dimethylpyrido[2,3-d]pyrimidine-2,4-dione (I).