Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British, Columbia, V6T 1Z1, Canada.
Chemistry. 2020 Apr 16;26(22):4958-4962. doi: 10.1002/chem.202000721. Epub 2020 Mar 24.
The Mitsunobu reaction is a powerful transformation for the one-pot activation and substitution of aliphatic alcohols. Significant efforts have focused on modifying the classic conditions to overcome problems associated with purification from phosphine-based byproducts. Herein, we report a phosphine free method for alcohol activation and substitution that is mediated by sulfuryl fluoride. This new method is effective for a wide range of primary alcohols using phthalimide, di-tert-butyl-iminodicarboxylate, and aromatic thiol nucleophiles in 74 % average yield. Activated carbon nucleophiles and a deactivated phenol were also effective for this reaction in good yields. Secondary alcohols were also successful substrates using aryl thiols, affording the corresponding sulfides in 56 % average yield with enantiomeric ratios up to 99:1. This new protocol has a distinct synthetic advantage over many existing phosphine-based methods as the byproducts are readily separable. This feature was exploited in several examples that did not require chromatography for purification. Furthermore, the mild reaction conditions enabled further in situ derivatization for the one-pot conversion of alcohols to amines or sulfones. This method also provides a boarder nucleophile scope compared to existing phosphine-free methods.
Mitsunobu 反应是一种将脂肪族醇一锅激活和取代的强大转化方法。人们已经做出了巨大的努力来改进经典条件,以克服与基于膦的副产物的纯化相关的问题。在此,我们报告了一种由磺酰氟介导的无膦的醇激活和取代方法。该新方法在 74%的平均产率下,使用邻苯二甲酰亚胺、二叔丁基-双(氨基甲酰基)二羧酸酯和芳香硫醇亲核试剂,对各种伯醇都有效。活性炭亲核试剂和失活的苯酚也可用于该反应,产率良好。使用芳基硫醇,仲醇也是成功的底物,以高达 99:1 的对映体过量比得到相应的硫醚,平均产率为 56%。与许多现有的基于膦的方法相比,这个新的方案具有明显的合成优势,因为副产物很容易分离。在几个不需要色谱纯化的例子中利用了这一特点。此外,温和的反应条件使得能够进一步进行原位衍生化,将醇一锅转化为胺或砜。与现有的无膦方法相比,该方法还提供了更广泛的亲核试剂范围。