Patent ID: 8541562

Claim:
A compound represented by the following formula I or formula II or a salt thereof: wherein, Base represents a purin-9-yl group or a 2-oxo-1,2-dihydropyrimidin-1-yl group that may have any one or more substituents selected from group α, wherein the group α consists of a hydroxyl group, a hydroxyl group protected with a protecting group for nucleic acid synthesis, linear alkyl groups having 1 to 6 carbon atoms, linear alkoxy groups having 1 to 6 carbon atoms, a mercapto group, a mercapto group protected with a protecting group for nucleic acid synthesis, linear alkylthio groups having 1 to 6 carbon atoms, an amino group, linear alkylamino groups having 1 to 6 carbon atoms, an amino group protected with a protecting group for nucleic acid synthesis and halogen atoms; R 1 represents a hydrogen atom, an alkyl group having 1 to 7 carbon atoms that may be branched or form a cyclic group, an alkenyl group having 2 to 7 carbon atoms that may be branched or form a cyclic group, an aryl group having 3 to 12 carbon atoms that may have any one or more substituents selected from the group α and may contain heteroatoms, an aralkyl group with an aryl moiety having 3 to 12 carbon atoms that may have any one or more substituents selected from the group α and may contain heteroatoms, or a protecting group for an amino group on nucleic acid synthesis; R 2 and R 3 represents, each independently, a hydrogen atom, a protecting group for a hydroxyl group on nucleic acid synthesis, an alkyl group having 1 to 7 carbon atoms that may be branched or form a cyclic group, an alkenyl group having 2 to 7 carbon atoms that may be branched or form a cyclic group, an aryl group having 3 to 12 carbon atoms that may have any one or more substituents selected from the group α and may contain heteroatoms, an aralkyl group with an aryl moiety having 3 to 12 carbon atoms that may have any one or more substituents selected from the group α and may contain heteroatoms, an acyl group that may have any one or more substituents selected from the group α, a silyl group that may have any one or more substituents selected from the group α, a phosphate group that may have any one or more substituents selected from the group α, a phosphate group protected with a protecting group for nucleic acid synthesis, —P(R 4 )R 5 (wherein R 4 and R 5 represent, each independently, a hydroxyl group, a hydroxyl group protected with a protecting group for nucleic acid synthesis, a mercapto group, a mercapto group protected with a protecting group for nucleic acid synthesis, an amino group, an alkoxy group having 1 to 5 carbon atoms, an alkylthio group having 1 to 5 carbon atoms, an cyanoalkoxy group having 1 to 6 carbon atoms or an amino group substituted with an alkyl group having 1 to 6 carbon atoms.); X represents an oxygen atom, a sulfur atom, an amino group or a methylene group; m is an integer from 0 to 2; and n is an integer from 0 to 1.