9-Benzyl-1,3-dimethyl-6-hydroxy-7-cyanomethyl-9H-8-oxopyrimido[2,1-f]purine-2,4-dione
9-Benzyl-1,3-dimethyl-6-hydroxy-7-(2-propynyl)-pyrimido-[2,1-f]purine-2,4,8(1H,3H,9H)-trione
6-Allyl-8-benzyl-5-hydroxy-1,3-dimethyl-1H,8H-1,3,4b,8,9-pentaaza-fluorene-2,4,7-trione
7,9-Dibenzyl-1,3-dimethyl-6-hydroxy-9H-8-oxo-pyrimido[2,1-f]purine-2,4-dione