Treatment of Nucleoside Analogs 2−5

Treatment of Nucleoside Analogs 2−5 with DMT-Cl. Nucleoside analogs 2−5 were treated with DMT-Cl (Scheme1) in pyridine at room temperature in the presence of Et3N.The reaction was found to be unusually sluggish (requiring 24−72 h), compared to the same reaction with natural nucleosides,and in all four instances resulted in incomplete conversion of starting nucleosides. The reaction of 2−5 with DMT-Cl produced the DMT-protected products 2a−5a in moderate(38−52%, Scheme 1) yield after flash column chromatography(FCC). Although 5′-O-DMT-protected nucleobases are known to be very sensitive to acidic environments, the isolated products 2a−5a failed to display this property. When analyzed by thin-layer chromatography (TLC), the spots associated with 2a−5a did not turn orange upon staining with 1 M HCl
(expected due to DMT cation formation). Moreover,compounds 2a−5a remained stable; i.e., no DMT was removed as judged by TLC and high-resolution mass spectrometry (HRMS)analysis, even after prolonged exposure to strong acid
(neat TFA, 12 h).

結果 (中文) 1:

治疗的核苷类似物 2−5 与 DMT 重生核苷类似物 2−5 患者 DMT-Cl (Scheme1) 在吡啶在室温下 Et3N.The 反应进行发现异常缓慢的 （需要 24−72 h），相比与天然核苷，同样的反应，在所有四个实例中导致不完全转换的开始核苷。2−5 DMT cl 的反应产生中度 （38−52%，计划 1) DMT 保护产品 2a−5a 后闪光柱 chromatography(FCC) 的产量。虽然 5 ′ O DMT 保护碱基被公认为对酸性环境非常敏感，孤立的产品 2a−5a 无法显示此属性。分析时用薄层色谱法 (TLC)，与 2a−5a 相关联的斑点没后 1 M HCl 染色橙（由于 DMT 阳离子形成预期）。此外，化合物 2a−5a 保持稳定;即，没有 DMT 中移除了由薄层色谱及高分辨质谱 (HRMS) 的分析，来判断，即使长时间暴露在强酸性（齐反式脂肪酸，12 小时）。

結果 (中文) 3:

治疗的核苷类似物2−5 dmt-cl.核苷类似物治疗5例，2−DMT CL（Scheme1）在吡啶存在下在室温，反应被认为是异常缓慢（需要24−72 h），与天然核苷相同的反应，在所有四个实例所造成的在开始核苷完全转换。反应2−5氯生产DMT DMT保护产物2a−5a在中度（38−52%，方案1）柱层析分离后的产量（FCC）。虽然5′- o-dmt-protected碱基是酸性环境非常敏感，分离产物2a−5a未能显示该属性。当进行薄层色谱（TLC），2A−5a相关景点没有变成橙色在1 M盐酸染色
（由于预期的DMT阳离子形成）。此外，化合物2a−5a保持稳定；即没有DMT为薄层和高分辨质谱判断删除（HRMS）分析，长期接触强酸后甚至
（整洁的TFA，12 h）。