Sulfide diaryl arene

At the time of the earlier review (66HC1155), it was already known that combinations of arenes with sulfur, or with sulfur mono- or dichlorides in the presence of Lewis acids (IV,B,1), or of aryl thiols, diaryl sulfides, or disulfides (IV,B,2 and 3) again heated with Lewis acid catalysts, generate thianthrenes, sometimes in acceptable preparative yields. A complimentary method is the treatment of aryl thiols with c. H2SO4. Routes from arenes and aryl thiols almost certainly involve the initial formation of diaryl sulfides. All these methods inevitably give symmetrical thianthrenes carrying identical substituents on each benzene ring (Scheme 9), unless the second sulfur is introduced in a controlled fashion into a preformed, unsymmetrical diphenyl sulfide. 

The use of transition-metal arene complexes to facilitate nucleophilic aromatic substitution features in a route to derivatives of thiosalicylic acid and hence to thioxanthone. The cyclopentadienyl iron complex of 2-chlorobenzoic acid is converted into the benzamide prior to displacement of the chloride by thiophenoxide. Photolytic decom-plexation followed by directed remote metallation of the diaryl sulfide yielded the heterocycle (Scheme 207) <2000SL975>. 

Oxidation of elemental sulfur and selenium with SbFs leads to the formation of doubly charged polyatomic cations [26]. These cations can react with polyfluorinated arenes to form diaryl sulfides or selenides (Eq. 12) [27]. 

By treatment with HSOsF-SbFs (1 1) and sulfur dioxide, alkylbenzenes, haloben-zenes, and alkylhalobenzenes are converted to their corresponding diaryl sulfoxides along with small amounts of diaryl sulfides as minor products (Eq. 35) [81]. In the absence of SO2 aryl sulfone formation is the dominant process, although sulfoxide is also formed. Unsymmetrical (mixed) sulfoxides can be prepared by adding one molar equivalent of an arene to the solution of the second arene and magic acid-SOa in Freon at low temperatures. 

Thiation of arenes is used both for preparation of aryl sulfides and for generation of heteroqfdic sulfur aromatic compounds. The diatyl thioether group is found in the structure of several approved pharmaceuticals, for example antihistamines. In a recent letter Wu and He disclosed that Cu(I) catalysis is very efficient for coupling of aryl thiols with aryl iodides (Scheme 15.69) [135], The procedure is very similar to that reported by the same authors for diaryl ether synthesis under the action of microwave irradiation (Scheme 15.65). 

The transition metal-free coupling of diphenyl disulfide with unfunctionalized arenes proceeds through a C—H activation process to afford the diaryl sulfides in moderate to excellent yields (Scheme 5.34) [55], A vast array of arenes were successfully used in this chemistry including bromomesitylene. Instead of forming the new carbon-sulfur bond at the brominated position, the substrate underwent a C—H activation to generate a bromi-nated diaryl sulfide. The retention of the bromine was attractive since it could be further... 

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