Protective group for synthesis of RNA and derivative

1. A protective group for 2′-hydroxyl group of a ribonucleoside or ribonucleotide, which is represented by the following general formula (I):

wherein, the oxygen atom attached with * represents an oxygen atom of the 2′-hydroxyl group of a ribonucleoside or ribonucleotide; R 1 and R 2 both represent a hydrogen atom, or independently represent a halogen atom, a C 1-6 alkyl group, or a C 1-6 halo-substituted alkyl group; R 3 and R 4 independently represent a hydrogen atom, a halogen atom, a C 1-6 alkyl group, or a C 1-6 halo-substituted alkyl group; and R 5 and R 6 represent the same fluoro-substituted C 1-6 alkyl group or the same perfluoro(C 1-6 alkyl) group.

2. The protective group according to claim 1 , wherein both R 1 and R 2 are hydrogen atoms.

3. The protective group according to claim 1 , wherein both R 3 and R 4 are hydrogen atoms.

4. The protective group according to claim 1 , wherein R 5 and R 6 represent the same fluoro-substituted C 1-6 alkyl group.

5. The protective group according to claim 1 , wherein R 5 and R 6 represent the same perfluoro(C 1-6 alkyl) group.

6. The protective group according to claim 1 , wherein both R 5 and R 6 are trifluoromethyl groups.

7. The protective group according to claim 1 , wherein the ribonucleoside or ribonucleotide is a phosphoroamidite compound.

8. A ribonucleoside or a ribonucleotide, wherein the oxygen atom of the 2′-hydroxyl group is protected with the protective group according to claim 1 .

9. The ribonucleoside or ribonucleotide according to claim 8 , which is a phosphoroamidite compound.

10. The ribonucleoside or ribonucleotide according to claim 9 , wherein the phosphoroamidite compound is a compound represented by the following general formula (II):

wherein, B represents a natural or non-natural nucleobase which may have a protective group; R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 have the same meanings as those defined above; R 11 represents a trityl group which optionally has a substituent, or a trityl group in which two phenyl groups among the three phenyl groups constituting the trityl group bind to each other via an oxygen atom to form a xanthene ring; R 12 and R 13 independently represent a C 1-6 alkyl group, or R 12 and R 13 bind to each other to form a saturated 5- or 6-membered ring, the ring constituting atoms optionally containing one or two or more oxygen atoms or sulfur atoms; R 14 and R 15 independently represent a hydrogen atom or a C 1-6 alkyl group, provided that R 14 may bind to R 13 to form a 5- or 6-membered ring; R 16 represents an electron withdrawing group, or when R 14 binds to R 13 to form a 5- or 6-membered ring, R 16 represents an electron withdrawing group or a hydrogen atom; and R 17 and R 18 represent a hydrogen atom or a C 1-6 alkyl group, or R 16 , R 17 , and R 18 bind to one another to represent an aryl group together with the carbon atoms to which they bind.

11. The ribonucleoside or ribonucleotide according to claim 10 which is a compound represented by the following formula (IIA):

wherein the symbols have the same meanings as those defined above.

12. A method for preparing an oligoribonucleic acid, comprising reacting the phosphoroamidite compound according to claim 10 in a reaction for synthesizing the oligoribonucleic acid.

13. A method for introducing a protective group for a 2′-hydroxyl group of a ribonucleoside or ribonucleotide, which is represented by the following general formula (I):

wherein, the oxygen atom attached with * represents an oxygen atom of the 2′-hydroxyl group of a ribonucleoside or ribonucleotide; R 1 and R 2 both represent a hydrogen atom, or independently represent a halogen atom, a C 1-6 alkyl group, or a C 1-6 halo-substituted alkyl group; R 3 and R 4 independently represent a hydrogen atom, a halogen atom, a C 1-6 alkyl group, or a C 1-6 halo-substituted alkyl group; and R 5 and R 6 represent the same fluoro-substituted C 1-6 alkyl group or the same perfluoro(C 1-6 alkyl) group, wherein the method comprises reacting a reagent comprising a compound represented by the following general formula (III):

wherein, R 3 , R 4 , R 5 , and R 6 have the same meanings as those defined above, and R 21 represents a hydroxyl group, with a ribonucleoside or a ribonucleotide of which the 2′-hydroxyl group is protected with a C 1-6 alkylthiomethyl group.

14. A method for introducing the protective group for a 2′-hydroxyl group of a ribonucleoside or a ribonucleotide, which is represented by the following general formula (I):

wherein, the oxygen atom attached with * represents oxygen atom of 2′-hydroxyl group of a ribonucleoside, a ribonucleotide or a derivative thereof; R 1 and R 2 both represent hydrogen atom, or independently represent a halogen atom, a C 1-6 alkyl group, or a C 1-6 halo-substituted alkyl group; R 3 and R 4 independently represent hydrogen atom, a halogen atom, a C 1-6 alkyl group, or a C 1-6 halo-substituted alkyl group; and R 5 and R 6 represent the same fluoro-substituted C 1-6 alkyl group or the same perfluoro(C 1-6 alkyl) group,

wherein the method comprises reacting a reagent comprising a compound represented by the following general formula (III):

wherein, R 3 , R 4 , R 5 , and R 6 have the same meanings as those defined above, R 21 represents R 22 —S—C(R 1 )(R 2 )—O—, wherein in the formula R 22 represents a C 1-6 alkyl group, and R 1 and R 2 have the same meanings as those defined above, or X—C(R 1 )(R 2 )—O—, wherein in the formula, X represents a leaving group, and R 1 and R 2 have the same meanings as those defined above, with a ribonucleoside or ribonucleotide of which the 2′-hydroxyl group is not protected.