1-Benzyl-6,8-dimethylimidazo<1,2-f>xanthine
8-Cyclohexyl-1,3-dimethyl-1H,8H-imidazo[2,1-f]purine-2,4-dione
7-(2,3-Dihydroxypropyl)-8-aminotheophylline
2-(8-bromo-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purin-7-yl)acetaldehyde
8-Benzylamino-7-(2,3-dihydroxy-propyl)-1,3-dimethyl-3,7-dihydro-purine-2,6-dione