The first example of an iodocyclisation reaction made recyclable by the use of an ionic liquid as the reaction medium is reported. Readily available 1-mercapto-3-alkyn-2-ols were smoothly converted into the corresponding 3-iodothiophenes (50–81% yields, 10 examples) when allowed to react with iodine (1–2 equiv.) in a proper ionic liquid, such as 1-ethyl-3-methylimidazolium ethyl sulfate (EmimEtSO4), as the solvent under mild reaction conditions (25 °C) and in the absence of an external base. The reaction medium can be recycled several times without significantly affecting the reaction outcome. Theoretical calculations have also been performed to investigate the role of the ionic liquid anion in the reaction.
本报告首次报道了通过使用
离子液体作为反应介质使
碘环化反应可循环使用的实例。以 1-ethyl-3-methylimidazolium ethyl sulfate (EmimEtSO4) 等适当的
离子液体为溶剂,在温和的反应条件下(25 °C),在没有外部碱的情况下,让 1-巯基-3-炔-2-醇与
碘(1-2 等量)反应,可顺利转化为相应的
3-碘噻吩(产率 50-81%,10 个实例)。反应介质可以多次循环使用,而不会对反应结果产生重大影响。此外,还进行了理论计算,以研究
离子液体阴离子在反应中的作用。