STUDIES ON CONDENSED PYRIMIDINE SYSTEMS .23. SYNTHESIS OF 2,4-DIAMINOPYRIDO[2,3-D]PYRIMIDINES FROM BETA-KETO ESTERS

The condensation of 2,4,6-triaminopyrimidine with β-keto esters gave 5-mono- and 5,6-disubstituted 2,4- diamino-7,8-dihydro-7-oxopyrido[2,3-d]pyrimidines (III) which were chlorinated by means of thionyl chloride and N,N-dimethylformamide to give 7-chloro-2,4-diaminopyrido[2,3-d]pyrimidines (V). Both the 7-oxo and 7-chloro derivatives were thiated to give 2,4-diammopyrido[2,3-d]pyrimidine-7-thiones (IV). Dethiation of the 7-thiones gave 2,4-diaminopyrido [2,3-d] pyrimidines having substituents in the 5 or 5,6 positions. © 1968, American Chemical Society. All rights reserved.