Transition metal-free, chemoselective arylation of thioamides yielding aryl thioimidates orN-aryl thioamides

Abstract

Reactions of secondary thioamides with diaryliodonium salts under basic, transition metal-free conditions resulted in chemoselective S-arylation to provide aryl thioimidates in good to excellent yields. Equimolar amounts of thioamide, base and diaryliodonium salt were sufficient to obtain a diverse selection of products within short reaction times. Reactions with thiolactams delivered N-arylated thioamides in good yield at room temperature.

Transition Metal‐Free N‐Arylation of Amino Acid Esters with Diaryliodonium Salts

“…In fact, iodonium salts 2 aa‐OTs and 2 aa‐Br suffered from a competing pathway where the anion acted as nucleophile to deliver the corresponding 4‐nitrophenyl tosylate ( 4‐OTs ) and bromide ( 4‐Br ), respectively. Such side‐products have previously been reported with diaryliodonium bromides, [28] whereas reactions with diaryliodonium tosylates are often efficient also at elevated temperatures [24a, 28b, 29] …”

Copper‐Catalyzed Selective N‐Arylation of Oxadiazolones by Diaryliodonium Salts

“…The soft nucleophilic nature of S-center in 7 sufficiently changed the reaction selectivity towards S-arylation. [35] The reaction proceeded smoothly, and product 8 was formed after 1 h of stirring. Notable, that arylation of 3-(aryl)-1,2,4oxadiazole-5-thiol is unknown and proposed procedure can be effective tool for synthesis of 5-(arylthio)-3-(aryl)-1,2,4-oxadiazoles.…”

“…[27] Particularly important the direct arylation of various nucleophiles by diaryliodonium salts. Thus, the strong nucleophiles are able to react with electron-poor aryl electrophile without the addition of transition metals (for instance, amines, [28][29][30][31] alkoxides, [32][33][34] S-nucleophiles, [35,36] etc.). The weaker nucleophiles require higher temperatures or the addition of transition metals, especially…”

Leaving Groups in Metal‐Free Arylations: Make Your Choice!

“…(Scheme 10b). [49] Analogous approaches recently involved phthalimides [50] and thioamides [51] as coupling partners to obtain N-arylphthalimides and aryl thioimidates, respectively. (Z)-N-aryl oxindole nitrones were obtained via coupling of 3-(hydroxyimino) indolin-2-ones with diaryliodonium salts again under basic conditions.…”