right positions. Their condensations with the intermediary dimeric 2′-terminal phosphodiesters 48 and 49 led to the fully protected 2′–5′-trimers 50–58 which were deblocked to form the free 2′–5′-trimers 59–63. Easy elimination of HBr on deprotection did not allow to form the trimeric (3′-bromo-3′-deoxy-β-D-xylofuranosyl)adenine analogue but only 63 carrying an unsaturated sugar moiety instead. The newly
一系列新的2'–5'-寡
核苷酸三聚体,其带有9-(2',3'-
脱水-β-D-核
呋喃糖基)-(59),9-(3'-
脱氧-β-D-
甘油- pent-3-enofuranosyl)-(63),9-(3'-azido-3'-deoxy-β-D-xylofuranosyl)-(62)和9-(3'-halo-3'-deoxy-β通过
磷酸三
酯法合成了在2'-末端的-D-二
呋喃呋喃糖基)
腺嘌呤(60和61)部分。的适当的保护,改性单体结构单元(6,9,16,19,27,33,36,37,和43通常通过一系列反应将保护基团引入正确的位置来获得)。他们与中间商二聚体2'-终端
磷酸二
酯缩合48和49导致了充分的保障2',5'-三聚体50-58,其被解封,形成游离',5'-三聚体59 - 63。
脱保护时容易消除HBr不允许形成三聚(3'-
溴-3'-
脱氧-β-D-木
呋喃糖基)
腺嘌呤类似物,而仅形成63个带有不饱和糖