A chromatography-free and aqueous waste-free process for thioamide preparation with Lawesson's reagent.
Beilstein J Org Chem
; 17: 805-812, 2021.
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| MEDLINE
| ID: mdl-33889221
ABSTRACT
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.
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01-internacional
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MEDLINE
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En
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Beilstein J Org Chem
Año:
2021
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Article