PROBLEM TO BE SOLVED: To obtain the new subject compound comprising a specific bicyclonucleoside and oligonucleotide analogue, hardly hydrolyzed by an enzyme in vivo, high in binding ability to a sense chain, readily synthesized, and used as an antisense molecule, etc.SOLUTION: This compound is a nucleoside analogue of formula I (B is pyrimidine or purine nucleic acid base or an analogue thereof X and Y are each H, an alkyl, an alkenyl, an alkynyl, a cycloalkyl, an aralkyl, an aryl an acyl or a silyl) or an amidite derivative and hardly hydrolyzed by an enzyme in vivo, high in binding ability to a sense chain, readily synthesized, and used for production, etc., of an oligonucleotide analogue used as an antisense molecule, etc., useful as a medicine. The nucleotide analogue is obtained by reacting a nucleic acid base with a compound of formula II (TBDPS is t-butylphenylsilyl Ts is tosyl Ac is acetyl Bn is benzyl), and deacetylating the product to cyclize the product.COPYRIGHT: (C)1998,JPO【目的】 生体内で酵素の加水分解を受けにくく、センス鎖との結合能が高く、しかも合成が容易であるオリゴヌクレオチド類縁体アンチセンス分子を提供する。【構成】 一般式:【化1】[式中、Bはピリミジンもしくはプリン核酸塩基又はそれらの類縁体である]で表される構造を1または2以上有するオリゴまたはポリヌクレオチド類縁体。