1,3,6-trimethylpyrido[2,3-d]pyrimidine-2,4-dione

6-hydroxy-1,3-dimethyl-9H-pyrimido[4,5-b]indole-2,4-dione

1,3-dimethyl-5-(2,5-dihydroxyphenyl)-6-aminouracil

1,4-dihydroxy-2,5-bis(1,3-dimethyl-6-aminouracil-5-yl)benzene

1,3-dimethyl-6-[(triphenyl-λ⁵-phosphanylidene)amino]pyrimidine-2,4-dione