Patent ID: 8039611

Claim:
A ribonucleoside derivative represented by General Formula (I): wherein R 1 represents a hydrogen atom or a protecting group for a hydroxyl group; R 2 represents a hydrogen atom, a protecting group for a hydroxyl group, or a group expressed by General Formula (III): wherein R 6 and R 7 are the same or different and each represents an alkyl group, or binds to each other to form a ring that optionally contains a hetero atom; R 8 represents a protecting group for a phosphate group; R 3 represents a hydrogen atom, an alkyl group optionally having a substituent, an aralkyl group optionally having a substituent, an alkenyl group optionally having a substituent, an alkynyl group optionally having a substituent, or an aryl group optionally having a substituent; and B represents an adenine nucleic acid base optionally protected by one or two acyl groups or an amidine protecting group at the N6 position of the adenine amino group, a cytosine nucleic acid base, a guanine nucleic acid base optionally protected by one or two acyl groups or an amidine protecting group at the N2 position of the guanine amino group, a uracil nucleic acid base optionally protected by an alkyl group or an acyl group at the N3 position, a thymine nucleic acid base optionally protected by an alkyl group or an acyl group at the N3 position, or a pyrimidine base having an alkyl group, an alkynyl group, an aryl group, a fluorescent functional group, a biotinyl group, an amino group or a spin label at the 5-position.