| abstract |
(57) Abstract: An intermediate for producing a non-natural oligonucleotide analog having excellent antisense or antigene activity and being stable in vivo, and 2-5A. An object is to provide an intermediate for producing an analog. A compound represented by the following structural formula (1) or a pharmacologically acceptable salt thereof. Embedded image R 1 and R 3 are the same or different and each represent a hydrogen atom, a hydroxyl group-protecting group for nucleic acid synthesis, and R 2 is a hydrogen atom, a C 1 to C 6 alkyl group or amino group for protecting nucleic acid synthesis And B represents purin-9-yl or 2-oxo-1,2 which may have a substituent selected from the following α group. -Dihydropyrimidin-1-yl group. (Α group) halogen atom, alkyl group having 1 to 6 carbon atoms, hydroxyl group, mercapto group, amino group and the like. |