Wu Ke, Ling Yichen, Ding An, Jin Liqun, Sun Nan, Hu Baoxiang, Shen Zhenlu, Hu Xinquan
College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, P.R. China.
Beilstein J Org Chem. 2021 Apr 9;17:805-812. doi: 10.3762/bjoc.17.69. eCollection 2021.
After completing the thio-substitution with Lawesson's reagent, ethanol was found to be effective in the decomposition of the inherent stoichiometric six-membered-ring byproduct from the Lawesson's reagent to a highly polarized diethyl thiophosphonate. The treatment significantly simplified the following chromatography purification of the desired thioamide in a small scale preparation. As scaling up the preparation of two pincer-type thioamides, we have successfully developed a convenient process with ethylene glycol to replace ethanol during the workup, including a traditional phase separation, extraction, and recrystallization. The newly developed chromatography-free procedure did not generate P-containing aqueous waste, and only organic effluents were discharged. It is believed that the optimized procedure offers the great opportunity of applying the Lawesson's reagent for various thio-substitution reactions on a large scale.
在用劳森试剂完成硫代取代反应后，发现乙醇能够有效地将劳森试剂中固有的化学计量比六元环副产物分解为高度极化的二乙基硫代膦酸酯。该处理显著简化了小规模制备中所需硫代酰胺后续的色谱纯化过程。在扩大两种钳型硫代酰胺的制备规模时，我们成功开发了一种便捷的方法，即在后处理过程中用乙二醇替代乙醇，包括传统的相分离、萃取和重结晶。新开发的无色谱法不会产生含磷的水性废物，仅排放有机废水。据信，优化后的方法为大规模应用劳森试剂进行各种硫代取代反应提供了巨大的机会。
