A series of nine 2, 4-diamino-5-[6-(or 7-) quinolylmethyl] pyrimidines has been prepared by condensations of qui-nolinecarboxaldehydes with 0-anilinopropionitriles, followed by treatment with guanidine. All compounds had basic or methoxy substituents at the 2-or 4- positions of the quinoline ring. All of the 6-quinolylmethyl derivatives were highly inhibitory against Escherichia coli dihydrofolate reductase (DHFR), provided that an &substituent ...