Highly efficient protocol for one-pot N-alkylation of nucleobases using alcohol in ionic liquid media as a straightforward route to access acyclic nucleoside was described. In this protocol purine, pyrimidine as well as azole derivatives underwent the N-alkylation reaction with primary or secondary alcohols using TsCl/TEA/K2CO3 in bmim[Br] to afford the products in good-to-excellent yields. The influence of factors in this method including the type of ionic liquid, base and sulfonating agents was discussed. The current method showed an appropriate selectivity in reaction with primary alcohols in comparison with secondary alcohols. This protocol is mild, safe and easy to apply; moreover, it is quite compatible with eco-friendly and green chemistry protocols, since the exploitation of toxic and hazardous materials such as DMF and alkyl halides has been prevented.
Triphenylphosphine-free approach for one-pot N-alkylation of purine, pyrimidine, and azole derivatives with alcohols using P2O5/KI: A facile and selective route to access carboacyclic nucleosides
A facile, selective, and mild synthetic approach for one-pot N-alkylation of nucleobases and other related N-heterocycles via alcohols, using a mixture of P2O5 and KI is described. The reaction of structurally diverse purines, pyrimidines, and/or azoles with primaryalcohols with the use of P2O5/KI and basic mixture of Et3N/K2CO3 in refluxing DMF affords the corresponding N-alkyl derivatives (carboacyclic
描述了一种使用P 2 O 5和KI的混合物通过醇通过一锅法对核碱基和其他相关N-杂环进行N-烷基化的简便,选择性和温和的合成方法。使用P 2 O 5 / KI和Et 3 N / K 2 CO 3的碱性混合物,使结构不同的嘌呤,嘧啶和/或唑与伯醇反应在回流中,DMF以良好至合理的产率得到相应的N-烷基衍生物(碳环核苷)。评估了包括溶剂,碱,温度和底物/试剂比率的不同参数对反应进程的影响。仲和叔醇不能与核碱基反应。当前方案的主要优点是形成水溶性副产物,其中提供了简单的后处理和纯化过程。
<b>Microwave-Assisted Ring Opening of Epoxides with Pyrimidine Nucleobases: A Rapid Entry into</b>
<b>
<i>C</i>
</b>
<b>-Nucleoside Synthesis</b>
作者:A. Khalafi-Nezhad、M. N. Rad、A. Khoshnood
DOI:10.1055/s-2004-815968
日期:——
Microwaveirradiation strongly accelerates the regioselective nucleophilic ring opening of epoxides by pyrimidine nucleobases. In the presence of tetrabutylammonium bromide (TBAB), various bases were elaborated to determine the proper base in which it can activate N 1 rather than N3 for alkylation. It was shown that MgO not only could serve as an eligible base, but also enhanced the selectivity and