SYNTHESIS OF 2,4-DIAMINO-5,10-DIDEAZA NONCLASSICAL ANTIFOLATES

Condensation of 2,4,6-triaminopyrimidine (8) with bromomalonaldehyde (9) afforded, after pivaloylation, 2,4-dipivaloyl-6-bromopyrido[2,3-d]pyrimidine (11). This 6-bromo derivative served as a key intermediate for the synthesis of 2,4-diamino-6-[2-(3',4'-dimethoxyphenyl)ethenyl]pyrido[2,3-d]pyrimidine (5) via a palladium catalyzed carbon-carbon coupling with 3,4-dimethoxystyrene (12). Compound 5, its 9,10-dihydro analogue 6 and the 5,6,7,8,9,10-hexahydro analogue 7 were of interest as potential inhibitors of dihydrofolate reductase. Compounds 6 and 7 were synthesized from 5 by catalytic hydrogenation oyer 5% Pd-C.