Potential Folic Acid Antagonists. 4. Synthesis and Dihydrofolate Reductase Inhibitory Activities of 2,4,6-Triamino-5-arylazopyrimidines

A series of 49 2,4,6-triamino-5-arylazopyrimidines have been synthesized and examined for their inhibitory activity toward chicken liver dihydrofolate reductase. This activity was comparatively independent of the substituent character of the 5-aryl group; however, para substituents (almost without exception) reduced activity, meta substituents maintained activity, and small o-alkyl substituents increased activity. The most active compound in the series was found to be 2,4,6-triamino-5-o-ethylphenylazopyrimidine.