Cu-Catalyzed One-Pot Synthesis of Unsymmetrical Diaryl Thioethers by Coupling of Aryl Halides Using a Thiol Precursor

Abstract

An efficient Cu-catalyzed one-pot approach for the synthesis of unsymmetrical diaryl thioethers using potassium ethyl xanthogenate as a thiol surrogate is developed. This new protocol avoids usage of intricate thiols and makes use of its easily available xanthate as a precursor, and thiol will be generated in situ to prepare the diaryl thioethers through a Cu-catalyzed double arylation. This strategy was further successfully utilized for the synthesis of symmetrical diaryl thioethers, aryl alkyl thioethers, and benzothiazoles.

One‐Pot Copper‐Catalysed Thioetherification of Aryl Halides Using Alcohols and Lawesson's Reagent in Diglyme

“…Subsequently, these odourless methods were developed using other sulfur surrogates [9] such as xanthogenate, [10] thioacetamide, [11] thiourea, [12] potassium thiocyanate, [13] thioacetate, [14] sodium hydrosulfide, [15] sodium sulfide, [16] elemental sulfur, [17] sulfonyl hydrazides, [18] Na 2 S 2 O 3 , [19] potassium 5-methyl-1,3,4-oxadiazole-2-thiolate, [20] aminothiourea, [21] sulfonyl hydrazide, [22] and phosphorothioic acids and related compounds. [23] However, the challenge of designing new synthetic and catalytic systems for C-S bond formation under mild and greener reaction conditions remains.…”

Copper-Catalyzed Thioetherification Reactions of Alkyl Halides, Triphenyltin Chloride, and Arylboronic Acids with Nitroarenes in the Presence of Sulfur Sources

“…25 Among these, S 8 and Na 2 S 2 O 3 show 3 particular and permissible sources of sulfur for S-arylation due to their low cost, odorless and being environmentally benign. However, these procedures still suffer from one or more disadvantages such as the need for N-or P-ligands, [19][20][21]22,25 elevated reaction temperatures and/or long reaction times, 20 using toxic, harmful and volatile organic solvents 20-23 or foul-smell of the sulfur source. 20 Some of these systems are also limited to the synthesis of symmetrical diaryls.…”

“…20 Some of these systems are also limited to the synthesis of symmetrical diaryls. 18b, [21][22][23][24] In addition, there are some other disadvantages associated with the use of aryl halides as the coupling partners which are generally environmental pollutants. Therefore, there is still a great interest to find new methods and alternative coupling partners for the preparation of unsymmetrical thioethers.…”

A Highly Efficient Method for the Copper‐Catalyzed Selective Synthesis of Diaryl Chalcogenides from Easily Available Chalcogen Sources

“…Nowadays, many more reagents are applied as chalcogen sources for the synthesis of diaryl chalcogenides; they include sulfur or selenium powder, [12] thiocyanates, [17] thioacetamide, [18] potassium ethyl xanthogenate, [19] potassium thioacetate, [20] thiourea, [21] selenoureas [22] and potassium selenocyanate. [23] Only a few methods, however, have been used in the selective synthesis of symmetrical and unsymmetrical diaryl chalcogenides.…”