Reaction of deoxynucleoside 3′-O-(methylthiomethyl) acetals 1 with N-iodosuccinimide (NIS) and dibutyl phosphate furnished the corresponding 3′-O-(dibutoxyphosphoryloxy)methyl acetals 6. Condensation of the latter with appropriately protected deoxynucleoside acceptors 3, in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf), afforded in most cases the (3′ → 5′) methylene acetal linked d(B1 Î¥ B2) dimers 4. In addition, TMSOTf-promoted coupling of donor 6 (B1 = CBz) with 3′-O-(methylthiomethyl)thymidine (8) yielded dimer 9. Reaction of 9 with NIS and dibutyl phosphate gave dimer 10, which was applied successfully in the TMSOTf-assisted fusion with acceptors 3(B2 = CBz and ABz), to afford the corresponding trimers d(CÎ¥TÎ¥C) 11 and d(CÎ¥TÎ¥A) 12.
脱氧核苷3′-O-(甲
硫基甲基)
乙缩醛1与
碘代琥珀
酰亚胺(NIS)和二
丁基磷酸酯反应,生成相应的3′-O-(二丁氧基
磷酰氧)甲基
乙缩醛6。后者与适当保护的脱氧核苷受体3在三甲基
硅基
三氟甲磺酸盐(TMSOTf)的存在下缩合,通常得到(3′ → 5′)亚甲基
乙缩醛连接的二聚体d(B1 ∧ B2) 4。此外,TMSOTf促进的供体6 (B1 = CBz)与3′-O-(甲
硫基甲基)
胸苷(8)的偶联反应生成二聚体9。9与NIS和二
丁基磷酸酯反应生成二聚体10,成功用于与受体3(B2 = CBz和ABz)的TMSOTf辅助融合,得到相应的三聚体d(C∧T∧C) 11和d(C∧T∧A) 12。