PROBLEM TO BE SOLVED: To provide a nucleoside in which 2-position hydroxy group is protected or a nucleotide derivative thereof in which RNA synthesis efficiency is satisfactory and can be deprotect under a mild condition, and purification after deprotection is easy.SOLUTION: There is provide a nucleoside expressed by formula (1) or a derivative of the nucleotide. (X1 and X2 severally independently denote H, substituted/unsubstituted silyl group, 4-methoxytrityl group, 4,4-dimethoxytrityl group or the like Ba denotes modified/unmodified nucleic acid base a formula (P1) is exemplified as Rp R denotes substituent having electron-donating property such as methoxy group R1 and R2 severally independently denote H or alkyl group).SELECTED DRAWING: Figure 2COPYRIGHT: (C)2019,JPO&INPIT【課題】RNA合成効率が良好で温和な条件で脱保護することができ、かつ脱保護後の精製の容易な、2’位の水酸基が保護されたヌクレオシド又はそのヌクレオチド誘導体の提供。【解決手段】式(1)で表すヌクレオシド又はそのヌクレオチドの誘導体。(X1及びX2は夫々独立にH、置換/非置換のシリル基、4-メトキシトリチル基、4,4’-ジメトキシトリチル基等;Baは修飾/非修飾の核酸塩基;Rpとしては式(P1)が例示される;Rはメトキシ基等の電子供与性を有する置換基;R1及びR2は夫々独立にH又はアルキル基)【選択図】図2
