Condensation of 5-O-tert-butyldimethylsilyl-1, 2-O-isopropylidene-α-D-erythro-3-pentulo-furanose (4) with 2, 4-dimethoxypyrimidin-6-ylmethyllithium (5) afforded a 3-pyrimidinylmethyl-ribose derivative (6). The protecting groups of 6 were changed to give the 5-O-benzoyl-1, 2-di-O-acetyl derivative (8). The intramolecular glycosylation of 8 by treatment with stannic chloride furnished the 6, 3'-methanol-O4-methyluridine derivative (9), which was further converted to 6, 3'-methanouridine (10) and 6, 3'-methanocytidine (11). The 2'-deoxygenation of 9 by way of the 2'-imidazolylthiocarbonyl dericative gave, after appropriate derivatization, 2'-deoxy-6, 3'-methanocytidine (16) and -uridine (17).
                                    5-O-叔丁基二甲基
硅基-1,2-O-异亚丙基-α-D-赤式-
3-戊基呋喃糖(4)与 2,4-二
甲氧基嘧啶-6-基
甲基锂(5)缩合,得到 3-
嘧啶基甲基
核糖衍
生物(6)。改变 6 的保护基团,得到 5-O-苯甲酰基-1,2-二-O-乙酰基衍
生物(8)。用
氯化锡处理 8 分子内糖基化,得到 6,3'-
甲醇-O4-甲基
尿苷衍
生物(9),进一步转化为 6,3'-甲
尿苷(10)和 6,3'-甲
胞苷(11)。通过 2'-
咪唑基
硫代羰基衍
生物对 9 进行 2'-脱氧反应,经适当衍生化后,得到 2'-脱氧-6,3'-甲
氰胞苷 (16) 和
尿苷 (17)。