Pyrido[2,3-d]pyrimidines, II [1]. One Step Synthesis of Pyrido[2,3-d]pyrimidines and Pyrimido[4,5-b]quinolines from 6-Amino Uracils

Article abstract of DOI:10.1007/BF00807031

Reduction of 6-azidouracils 2 with hydrogen palladium or sodium dithionite afforded the corresponding 6-aminouracils 5 which could also be obtained by reaction of 2 with triphenylphosphane via phosphazenes and subsequent hydrolysis (Staudinger reaction). The use of trimethylphosphite instead of phosphanes yields with 2b the expected trimethoxyphosphazene 3c, whereas 2a reacts to the phosphonoaminopyrimidine 4. The syntheses of 5-hydroxy pyrido[2,3-d]pryimidine-2,4,7-triones 6, pyrido[2,3-d]pyrimidine-2,4,5-triones 8, cyclopenta[e]pyrido[2,3-d]pyrimidin-2,4,5-triones 7a, c, and tetrahydro-pyrimido[4,5-b]quinolin-2,4,5-triones 7b, d by condensation of 6-aminouracils 5 with malonates, ethylaceto/benzoylacetate, ethyl 2-oxocyclopentanecarboxylate and ethyl 2-oxocyclohexanecarboxylate, respectively, are described.