1-{4-[2-(2-methyl-3H-imidazol-4-yl)-8-phenyl-purin-9-yl]-phenyl}-cyclobutylamine

9-[4-(1-amino-cyclobutyl)-phenyl]-8-phenyl-9H-purine-2-carboxylic acid methyl-amide

1-[4-(8-phenyl-purin-9-yl)-phenyl]-cyclobutylamine

1-[4-(8-phenyl-2-piperazin-1-yl-purin-9-yl)-phenyl]-cyclobutylamine