Purine derivatives and medicinal use thereof

A purine derivative of the following formula (I),

• or a pharmaceutically acceptable salt thereof, wherein
• R1 is
• a hydrocarbon group having 17 or less carbon atoms or
• a substituted hydrocarbon group having 17 or less carbon atoms selected from the group consisting of
• (1) hydrocarbon group having 17 or less carbon atoms in which a carbon atom and two hydrogen atoms of one or more >CH2 g roups, —CH3 g roups, or ═CH2 g roups which do not directly bind with the carbon atom at 2 position of the purine ring are replaced by carbonyl groups, sulfonyl groups, O, or S,
• (2) hydrocarbon group having 17 or less carbon atoms in which a carbon and one hydrogen atom of one or more >CH— groups, >CH2 g roups, —CH3 g roups, ═CH2 g roups, ═CH— groups, or ≡CH which do not directly bind with the carbon atom at 2 position of the purine ring are replaced by N, C-halogen, or C—C≡N, or
• (3) hydrocarbon group having 17 or less carbon atoms in which
• (i) a carbon atom and two hydrogen atoms of one or more >CH2 g roups, —CH3 g roups, or ═CH2 g roups which do not directly bind with the carbon atom at 2 position of the purine ring are replaced by carbonyl groups, sulfonyl groups, O, or S, and
• (ii) a carbon and one hydrogen atom of one or more >CH— groups, >CH2 g roups, —CH3 groups, ═CH2 g roups, ═CH— groups, or ≡CH which do not directly bind with the carbon atom at 2 position of the purine ring are replaced by N, C-halogen, or C—C≡N;
• and
• R2 is
• a hydrocarbon group having 16 or less carbon atoms or
• a substituted hydrocarbon group having 16 or less carbon atoms selected from the group consisting of
• (1) hydrocarbon group having 16 or less carbon atoms in which carbon atom and two hydrogen atoms of one or more >CH2 g roups, —CH3 g roups, or ═CH2 g roups which do not directly bind with the methylene group at 7 position of the purine ring are replaced by carbonyl groups, sulfonyl groups, O, or S,
• (2) hydrocarbon group having 16 or less carbon atoms in which a carbon and one hydrogen atom of one or more >CH— groups, >CH2 g roups, —CH3 g roups, ═CH2 g roups, ═CH— groups, or ≡CH which do not directly bind with the methylene group at 7 position of the purine ring are replaced by N, C-halogen, or C—C≡N, or
• (3) hydrocarbon group having 16 or less carbon atoms in which
• (i) a carbon atom and two hydrogen atoms of one or more >CH2 g roups, —CH3 g roups, or ═CH2 g roups which do not directly bind with the methylene group at 7 position of the purine ring are replaced by carbonyl groups, sulfonyl groups, O, or S, and
• (ii) a carbon and one hydrogen atom of one or more >CH— groups, >CH2 g roups, —CH3 groups, ═CH2 g roups, ═CH— groups, or ≡CH which do not directly bind with the methylene group at 7 position of the purine ring are replaced by, N, C-halogen, or C—C≡N.