"yl]-1,7-dihydro-purin-6-one [0573] prepared from Example XV.1 and trifluoroacetic acid. [0574] Mass spectrum (ESI+): m/z=473 [M+H]+ [0575] The following compounds may also be obtained analogously to the preceding Examples and other methods known from the literature: [0576] (1) 8-(3-amino-piperidin-1-yl)-7-benzyl-1-ethyl-2-benzylamino-1,7-dihydro-purin-6-one [0577] (2) 8-(3-amino-piperidin-1-yl)-7-" . . . .