作者:Adel A.-H. Abdel-Rahman、Magdy A. Zahran、Ahmed E.-S. Abdel-Megied、Erik B. Pedersen、Claus Nielsen
DOI:10.1055/s-1996-4187
日期:1996.2
5-Substituted S 2-alkyl-2-thiouracils 1a-i were treated with 1,1,1,3,3,3-hexamethyldisilazane and ammonium sulfate at reflux temperature and condensed with 1,2,3,5-tetra-O-acetyl-β-D-ribufuranose in acetonitrile using trimethylsilyl trifluoromethanesulfonate as a catalyst to afford the corresponding protected nucleosides 2a-i which were deprotected with saturated ammonia in methanol. When the nucleobase was substituted with ethoxycarbonyl or cyano groups in the 5-position or was unsubstituted, the deprotection reaction of the nucleoside also resulted in replacement of the methylthio group. This was not observed with 5-alkyl and 5-methoxy substituents.
5-取代的S 2-烷基-2-硫脲嘧啶1a-i与1,1,1,3,3,3-六甲基二硅氮烷和硫酸铵在回流温度下反应,然后在乙腈中与1,2,3,5-四-O-乙酰基-β-D-核呋喃糖缩合,使用三甲基硅基三氟甲磺酸作为催化剂,得到相应的保护核苷2a-i,这些核苷随后用甲醇中的饱和氨进行去保护。当核碱基在5位上被乙氧羰基或氰基取代或不取代时,核苷的去保护反应也会导致甲硫基团的替换。对于5-烷基和5-甲氧基取代基,则没有观察到这种现象。