A thorough study on the reaction of DMAD with 1-arylaminoimidazole-2-thiones. Expeditious synthesis of imidazo[2,1-b][1,3]thiazoles through a novel arylamino rearrangement
作者:Constantinos Neochoritis、Nicolaos Eleftheriadis、Constantinos A. Tsoleridis、Julia Stephanidou-Stephanatou
DOI:10.1016/j.tet.2009.11.056
日期:2010.1
Upon reaction of 1-arylamino-imidazole-2-thiones 1 with dimethyl acetylenedicarboxylate (DMAD) in the presence of 2.2 equiv of sodium hydride, imidazothiazoles 4 were exclusively formed (71–82% yield). However, from the reaction of 1 with DMAD in the absence of base, only the S-substituted products 5 were formed as an E/Z mixture (53–55%), which could also be converted to 4 with 2.0 equiv of sodium
在存在2.2当量的氢化钠的情况下,使1-芳基氨基-咪唑-2-硫酮1与乙酰二羧酸二甲酯(DMAD)反应后,仅形成咪唑并噻唑4(产率为71–82%)。但是,从1与DMAD在不存在碱的情况下反应,仅形成S取代的产物5为E / Z混合物(53-55%),也可以用2.0当量的氢化钠将其转化为4(65–68%)。此外,将5a - E / Z转化为芳基氨基取代的衍生物8a与1.1当量的氢化钠反应后,产率为78%。在甲醇中存在甲醇钠的情况下,硫酮1a与DMAD的反应也可能形成8a(75%的收率)。通过用DMAD(91%)加热1a或加热苯中的5a - E / Z混合物(90%收率)观察到硫酮1a的咪唑3-NH取代生成6a - Z。最后,当5a - E与乙酸酐反应时,乙酰化衍生物7a - Z是唯一的分离产物(58%)。全部分配明确实现了1 H和13 C NMR化学位移。