Abstract
We report a novel, and versatile solid-phase synthesis of pyrimido[4,5-d]pyrimidine-2,4(1H,3H)-diones
starting from the polymer-bound pyrimidine 3.
The key step is based on the reaction of the support-bound pyrimidine 3 with isocyanates 4,
involving formation of a carbamate intermediate, followed by a base-catalysed
intramolecular ring closure, to give polymer-bound 3-monosubstituted
1H-pyrimido[4,5-d]pyrimidine-2,4(1H,3H)-diones 5. At this stage, subsequent treatment
with alkyl halides 6 lead to 1,3-disubstituted
2H-pyrimido[4,5-d]pyrimidine-2,4(1H,3H)-dione
intermediates 7, which after oxidation
and cleavage with various amines 8 gave
1,3-disubstituted 7-amino-2H-pyrimido[4,5-d]pyrimidine-2,4(1H,3H)-diones 9 in moderate yields and high purity.
Key words
solid-phase - pyrimidine - base-catalysed ring
closure - intramolecular cyclisation - pyrimido[4,5-d]pyrimidine-2,4(1H,3H)-diones
