Sulfides, diaryl unsymmetrical

When thionyl chloride is used, diaryl sulfoxides are usually the main products. Unsymmetrical diaryl sulfides can be obtained by treatment of an aromatic compound with an aryl sulfenyl chloride (ArSCl) in the presence of a trace amount of iron powder.Aromatic amines and phenols can be alkylthiolated (giving mostly ortho product) by treatment with an alkyl disulfide and a Lewis acid catalyst. With certain substrates (primary amines with a chloro group, or a group not replaceable by chloro, in the para position), treatment with S2CI2 and NaOH gives thiophenolate salts ... 

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. 

Aryl ethers. Unlike other Bi(V) arylaling reagents, this reagent converts phenols into unsymmetrical diaryl ethers (equation 1). Yields are in the range 50-75%. Yields are improved if the phenol is treated first with Bi(C6H5)s and then with TFA. The reagent also converts aryl thiols into mixed diaryl sulfides. 

Unsymmetrical diaryl sulfides (60 R = 2-NO2, 4-NO2, 2,4-(N02)2 R = H, 4-NMe2) were obtained in 80-97% yields from the reaction under PTC conditions of nitro-activated aryl halides with arenethiolates generated in situ from the reduction of the corresponding diaryl disulfides with aminoiminomethanesul-finic acid (61).192 Arylthiolates carrying electron-withdrawing substituents were not sufficiently reactive. The reaction could also be applied to the synthesis of diaryl selenides, but not of ditellurides. 

Abbady MA, Hebbachy R (1993) Synthesis and application of some symmetrical and unsymmetrical diaryl sulfides and diaryl sulfones containing pyrazolinyl and isoxazolinyl moieties. Indian J Chem Sect B 32 1119-1124... 

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. 

In 2011, Park etal. [52] showed that aryl sulfides could be obtained from the coupling reaction of 5-aryl or 5-alkyl thioacetates and aryl bromides using Pd(dba)2 and dppf 5-phenyl thioacetate was the first thioacetate to be investigated, but others were also investigated (Figure 2.10). Symmetrical and unsymmetrical diaryl sulfides could also be prepared using potassium thioacetate in a one-pot... 

Figure 2.11 A cross-section of results for the Pd-catalyzed synthesis of unsymmetrical and symmetrical diaryl sulfides with potassium thioacetate, as reported by Park et al. [52],...

Nucleophilic Displacement. PhTMS-BF3 0Et2 system has been shown to be useful in the transformation of allylic alcohols to allylic sulfides (eq IS). Preparation of unsymmetrical diaryl sulfides can be achieved by reaction of arenediazonium tetraflu-oroborates with PhSTMS (eq 19). In some cases, addition of cupric sulfide increases the yield of the diaryl sulfides. The use of (phenylthio)trimethylsilane as a coupling partner in palladium catalyzed reactions with aUyl carbonates (eq 20) and aryl iodide (eq 21) has been explored. ... 

SCHEME 5.31 Nickel-catalyzed synthesis of unsymmetrical diaryl sulfides [47]. 

The reaction of alkyl aryl sulfides with diaryliodonium salts generated unsymmetrical diaryl sulfides in moderate to excellent yields through cleavage of the sulfur-carbon(sp ) bond and formation of a new sulfur-carbon(sp ) bond (Scheme 5.38) [60]. The synthesis was transition metal free and tolerated a host of different electron-withdrawing and donating groups. Another noteworthy aspect of the chemistry was that it was successful in an acidic environment. This renders the work complementary to the transition metal-catalyzed routes that are typically carried out under basic conditions. In related work, the... 

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