636-04-4Relevant articles and documents
AMIDE AND THIOAMIDE BANDS OF BENZANILIDE AND THIOBENZANILIDE IN THE VIBRATIONAL SPECTRA
Petrov, I.,Grupce, O.
, p. 481 - 484 (1984)
It has been widely accepted that in secondary amides and secondary thioamides, in the spectral region between 1600 and 1200 cm-1 two characteristic bands could be recognized (Amide II and Amide III for amides and B and C bands for thioamides).Our spectra of benzanilide, C6H5(C=O)NHC6H5, and thiobenzanilide, C6H5(C=S)NHC6H5, show that in this region there are, at least, four prominent bands which shift on deuteration.That could indicate that all these bands are in connection with the vibrations of amide and/or thioamide groups.Some other amide and thioamide bands have been also discussed.
Chemoselective Transamidation of Thioamides by Transition-Metal-Free N?C(S) Transacylation
Hong, Xin,Li, Guangchen,Szostak, Michal,Xing, Yangyang,Zhang, Jin,Zhao, Hui
, (2022/02/25)
Thioamides represent highly valuable isosteric in the strictest sense “single-atom substitution” analogues of amides that have found broad applications in chemistry and biology. A long-standing challenge is the direct transamidation of thioamides, a process which would convert one thioamide bond (R?C(S)?NR1R2) into another (R?C(S)?NR3N4). Herein, we report the first general method for the direct transamidation of thioamides by highly chemoselective N?C(S) transacylation. The method relies on site-selective N-tert-butoxycarbonyl activation of 2° and 1° thioamides, resulting in ground-state-destabilization of thioamides, thus enabling to rationally manipulate nucleophilic addition to the thioamide bond. This method showcases a remarkably broad scope including late-stage functionalization (>100 examples). We further present extensive DFT studies that provide insight into the chemoselectivity and provide guidelines for the development of transamidation methods of the thioamide bond.
A chromatography-free and aqueous waste-free process for thioamide preparation with Lawesson's reagent
Wu, Ke,Ling, Yichen,Ding, An,Jin, Liqun,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu,Hu, Xinquan
, p. 805 - 812 (2021/05/03)
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.
