3-substituted adenines via2-thioxanthines

Compounds of formula (I) are described, wherein R3 is selected from the group consisting of C1-10 alkyl, C1-10 alkenyl, C3-10 cycloalkyl, C4-10 cycloalkylalkyl or C3-10 cycloalkenyl, wherein said alkyl, alkenyl, cycloalkyl, cycloalkylalkyl or cycloalkenyl is optionally substituted at one position with hydroxy; or benzyl, wherein said benzyl is optionally substituted at one or two positions with halogen, alkoxy, cycloalkoxy or polycycloalkyl, and wherein said alkyl moiety on said alkoxy or cycloalkoxy substituent is optionally substituted at one position with hydroxy; R8 is selected from the group consisting of hydrogen, C,.10-alkyl, C,.,0-alkenyl, C3.10-cycloalkyl, C4.10-cycloalkylalkyl or C3.10-cycloalkenyl, in which said alkyl, alkenyl, cycloalkyl, cycloalkylalkyl or cycloalkenyl is optionally substituted in one position with hydroxy; or benzyl, wherein said benzyl is optionally substituted at one or two positions with halogen, alkoxy, cycloalkoxy or polycycloalkyl, and wherein said alkyl moiety on said alkoxy or cycloalkoxy is optionally substituted at one position with hydroxy; R6' and R6b are independently selected from the group consisting of hydrogen, C1-10 alkyl, C1-10 alkenyl, C3-10 cycloalkyl, C4-10 cycloalkylalkyl or C3-10 cycloalkenyl, wherein said alkyl, alkenyl, cycloalkyl, cycloalkylalkyl or cycloalkenyl is optionally substituted at one position with hydroxy; and pharmaceutically acceptable salts thereof.