Furanoside–pyranoside isomerization of tubercidin and its 2′-deoxy derivatives: influence of nucleobase and sugar structure on the proton-catalysed reaction
作者:Frank Seela、Sabine Menkhoff、Silvia Behrendt
DOI:10.1039/p29860000525
日期:——
2′-Deoxy-2-methoxytubercidin (6a) which was prepared from the nucleobase (1a) with the halogenose (2)via phase-transfer glycosylation isomerizes rapidly under acidic conditions. Two pyranosides [(7a) and (8a)] and the anomeric furanoside (5a) are formed. The isomerization process was followed kinetically, demonstrating that furanoside formation is kinetically controlled whereas the β-pyranoside (7a)
由核苷碱基(1a)与卤代糖(2)经由相转移糖基化反应制得的2'-脱氧-2-甲氧基微球蛋白(6a)在酸性条件下迅速异构化。形成两个吡喃糖苷[((7a)和(8a)]]和异头呋喃糖苷(5a)。动力学上遵循异构化过程,表明呋喃糖苷的形成在动力学上受到控制,而β-吡喃糖苷(7a)是热力学上最稳定的产物。与(6a)相比,从2'-脱氧结核菌素(6b)获得了相似的结果,但异构化较慢。核糖核苷结核菌素(6c)仅在强酸处理下才异构化,通过裂解N-糖基键产生α-呋喃糖苷(5c)和核碱基(1c)。