ring-formation to give after deprotection the bicyclic nucleoside 34. The surprisingly efficient formation of an oxetane was first discovered by serendipity on a corresponding methylfuranoside derivative. The allo-configured bicyclic nucleoside 34 was easily shortened to a ribo-configured analogue 35 by a diol-cleaving reaction and subsequent reduction. Both 34 and 35 are conformationally restricted in the important
已经有效地合成了分别具有一个和两个羟甲基取代基的两个[3.2.0]双环核苷35和34。由双
丙酮-
D-葡萄糖容易地制备受保护的(3'-C-
乙烯基-β-D-烷基
呋喃糖基)胸腺
嘧啶衍
生物28,并且胸腺
嘧啶部分被BOM-基团保护。在2'-位引入离去基团后,随后的核苷31用作立体选择性二羟基化和区域选择性氧杂
环丁烷环形成的底物,以在脱保护后得到双环核苷34。令人惊奇地有效形成氧杂
环丁烷偶然发现了相应的甲基
呋喃糖苷衍
生物。通过二醇裂解反应和随后的还原,容易将异构型双环核苷34缩短为
核糖构型的类似物35。